"Is'
ORGANOMAGNESIUM COMPOUNDS IN BENZENE SOLVENT
AND THEIR APPLICATION IN SYNTHESIS
OF ORGANOBERYILIUM COMPOUNDS
THESIS
Presented to the Graduate Council of the
North Texas State University in Partial
Fulfillment of the Requirements
For the Degree of
MASTER OF SCIENCE
By
Charles M. Selman, B. S.
Denton, Texas
January, 1966
TABLE OF CONTENTS
PageLIST OF TABLES . . . . . * . . . . . . . . . . . . . . iv
LIST OF ILLUSTRATIONS .0.... *.. . . . .. 0 .0. .0 v
Chapter
I. INTRODUCTION. . . . . . . . . . . . . . . . . . . 1
II. EXPERIMENTAL PROCEDURE .0.0.0. . . .0.0.a. .*. . 12
MaterialsPreparation and Analysis of the Organo-
magnesium HalidesCryoscopic Molecular Weight DeterminationPreparation and Analysis of Di-n-
pentylmagnesium,Preparation and Analysis of Organo-
beryllium CompoundsInfrared Absorption Studies
III. RESULTS AND DISCUSSION........*... . . . . . 30
BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . . 46
iii
LIST OF TABLES
Table Page
I. InvestigationSummary--a-........ 5
II. Impurity Analysis of Magnesium . . . . . . . . . . 12
III. Analysis of n-Pentylmagnesium Compounds inBenzene Solvent . . . . . . . . . . . . . . .31
IY. Molecular Structure Dependence Upon theOrganic Portions of OrganomagnesiumHalide Compounds in Benzene Solvent . . . . . .38
V. Synthesis and Association Studies of Organo-berylliummCompounds . ......... ... 40
VI. Infrared Absorptions ............... 43
VII. Electronegativity and Mass Values . . . . . . . . . 44
iv
LIST OF ILLUSTRATIONS
Figure Page
1. Molecular Weight Apparatus . . . . . . . . . . . . 18
2. Hydrolysis Apparatus . . . . . . . . - - . - - - . 26
3. Nuclear Magnetic Resonance Monitoring of theDi-n-pentylmagnesium Synthesis . . . . . . . . 34
4. Infrared Spectra of 1-Pentylmagnesium HalideComplexes in Benzene . . . . . . . . . . . . . 42
V
CHAPTER I
INTRODUCTION
The concept that organomagnesium compounds are of two
kinds, the di-organomagnesium compounds, R2Mg, and the
organomagnesium halide compounds, RMgX, was accepted until
the early part of this decade. Several attempts had been
made to prepare the organomagnesium halide species by methods
other than the classical Grignard procedure, with little
success (12). The products which resulted from these at-
tempts using hydrocarbon solvents were generally described
as involatile and infusible solids which showed little if
any solubility in hydrocarbon solvents. Due to lack of
analysis, these products were assumed to have the RMgX
structure that was used to describe the Grignard reagent.
Procedures for the preparation of organomagnesium halide
compounds in the absence of ether have been reported in
several recent publications (4, 5, 16, 17). These publi-
cations describe techniques for preparingthe organomagnesium
halide species which consist of direct addition of alkyl or
aryl halides to magnesium metal. These organomagnesium
halides are formed in the absence of the usual ethereal
solvent and exhibit a degree of solubility in hydrocarbon
solvents which is primarily dependent upon the organic radical.
1
2
Zokharkin, Okhobystin, and Strubin (16) carried out a
systematic investigation to determine the optimum synthetic
conditions and the yields of these organomagnesium halide
compounds. They reported the yields on the whole to be
comparable to those in ether solutions. In a later paper
(17), these authors showed that organomagnesium compounds in
hydrocarbon solvents are useful for the synthesis of a variety
of organometallic compounds.
Bryce-Smith and Cox (5) found the solubilities of organo-
magnesium halides to increase in the order Cl<Br <I, and to
increase with the length of the alkyl chain of the organo-
magnesium halide. For the system of n-butyl magnesium iodide
in isopropyl benzene and tetrahydronapthalene an empirical
formula R3 Mg2X was found to be representative of the solutions.
An explanation of the observed empirical formula R3Mg2X by the
species R2Mg and RMgX is precluded by the low solubility observed
for di-n-butylmagnesium in boiling isopropyl benzene. A com-
bination of the determined empirical formula and the rather
high relative viscosity values of these solutions led the
authors to predict polymeric organomagnesium halide species
with repeating units of the following types:
(a) or (b)
'.:.-Mg 0MgJ -,'0.Mg . :.Mg Mg*. ..- . .- X -' - ---.- R-'x4' -X ' - ''
3
The dotted lines in these structures represent electron-
deficient bonding which had been predicted for linear polymeric
structures of dimethylberyllium (13). Additional evidence for
this polymeric structure was the observation of magnesium
halide precipitation from concentrated solutions upon standing,
resulting in larger alkyl to halide ratios. This dispropor-
tionation by elimination of MgX2 was taken as favoring the
(b) repeating polymeric unit over (a).
The work reported by D. Bryce-Smith and G. F. Cox (5)
along with several recent publications describing experimental
results designed to elucidate the long disputed question of
the structure of the Grignard reagent in ether stimulated
the work reported here, in an effort to obtain additional
evidence of the structure of the organomagnesium complex in
benzene solvent. Since the primary objective of this work
was to prepare organoberyllium compounds using the organo-
magnesium complexes in hydrocarbon solvents, it seemed an
insight into the structure of these complexes would be bene-
ficial in this work.
The techniques used and experimental evidence obtained
from the structure elucidation of the ethereal Grignard re-
agent have been most helpful in organization of the methods
used to study the structure of organomagnesium halide com-
plexes in benzene solvent. For this reason a review of the
most important publications leading to the structure deter-
mination of the Grignard reagent will be presented here.
4
During the early part of this century two main pro-
posals for the structure of the Grignard reagent were made.
The well-known formula RMgX was first proposed by Grignard
(10). The other formula, R2Mg . MgX2, was proposed by
Jolibois (11). The work by R. E. Dessy (8) described ex-
periments which indicated that the species RMgX was es-
sentially non-existent in Grignard solutions, which up until
this time had been represented by the equilibria
2RMgX #=N!! R2Mg -FMgX2 # R2Mg . MgX2
In this paper and in a later publication (9) Dessy presented
evidence that was interpreted to show that equimolar mixtures
of MgBr2 and Et2Mg in ether had the same characteristics as
the Grignard reagent, and when Mg28Br2 was used no exchange
between the organomagnesium and the magnesium halide was
observed. Consequently, Dessy concluded that no alkyl ex-
change takes place in ether solution and therefore the left
side of the above equilibrium was not important in the de-
scription of the system.
The work by Dessy was widely accepted and little pursuit
of the Grignard structure was made by investigators until the
early part of this decade. Recently, however, several pub-
lications (2, 14, 15, 16) by different investigators have
shown evidence for the existence of RMgX species both in
diethyl ether and tetrahydrofuran solvents.
5
The primary techniques used by these investigators were
ebullioscopic studies for molecular association determinations
and gas chromatography and neutralization determinationsfor
stoichiometry studies. The work by G. D. Stucky and R. E.
Rundle (14) applied the technique of X-ray diffraction to
determine the crystal structure of the phenylmagnesium bromide
Grignard reagent. A summary of the findings of these in-
vestigators is shown in the following table:
TABLE I
INVESTIGATION SUMMARY
Authors Reference Solvent Grignrd AsociationReagentSpecies
E. C. AshbyW. E. Becker (2) THF EtMgCl Monomer
EtMgBr MonomerEt20 EtMgCI Dimer
MeMgCl DimerMesitylMgBr. Dimer
G. D. StuckyR. E. Rundle (13) Crystalline PhMgBr Monomer
di-etherateC. Blomberg (14, 15) Et20 EtMgBr Monomer
___THF EtMgBr Monomer
The main points that can be determined from the above summary
of data are: the species RMgX does exist in ether solvent,
and the exact nature of the Grignard reagent is dependent
upon the variables of solvent, R group, and halide.
Two recent publications by E. C. Ashby (1, 3) make very
clear the dependence of the Grignard reagent structure upon
6
the variables of solvent, R group, and halide. This was
accomplished first by presenting data which shovsthat the
degree of association of several Grignard reagents in
diethyl ether solvent varies between one and two in the con-
centration range 0.1 - 0.4 molarity. The data also shows that
the chloride species demonstrates this effect very little
compared to the bromide and iodide species. Ashby concluded
that re-evaluation of the data summarized in Table I with
respect to the association-concentration dependence leads to
the conclusion that RMgX species definitely exist in solution.
This evaluation thus provides evidence that dimeric species
in solution can be explained by both a symmetrical (RMgX)2
and an unsymmetrical R2Mg . MgX2 species. From these results
the Grignard structure in diethyl ether can thus be charac-
terized by a monomeric species, which exists as: (A) RMgX;
(B) a mixture of R2Mg and MgX2 ; (C) an equilibrium mixture of
(A) and (B). The Grignard structure in diethyl ether may also
be characterized by a dimeric species stated to be present in
(D) a symmetrical dimer or (E) an unsymmetrical dimer. This
equilibriumis shown in the following diagram:
OX% R XR-Mg' Mg-R" -2RMgX-hR 2 Mg + MgX2 Mg Mg
(D) (A) (B) (E)
The second article by Ashby (1) explains the distinction
between the composition of the Grignard compounds in diethyl
7
ether and tetrahydrofuran solvents by the difference in
basicity of the two solvents. Thus, tetrahydrofuran co-
ordinates with magnesium more strongly than diethyl ether
and a bridge compound is not formed. By applying an even
stronger base such as triethyl amine Ashby showed that the
Grignard reagent revealed only monomeric species throughout a
wide concentration range. This work gives a more complete
picture of organomagnesium halide complexes in a medium which
shows enough basic character to associate with the magnesium
in the complex. A knowledge of the different parameters,
which had to be understood before the structure of the organo-
magnesium halide complex in polar solvents could be elucidated,
was very helpful in designing experiments that would give some
insight into the structure of the organomagnesium halide com-
plexes in non-polar hydrocarbon solvents.
It seemed that an insight into the structure of these
organomagnesium halide complexes in hydrocarbon solvents
would be beneficial in accomplishing the second objective of
this work. This objective was to prepare organoberyllium
compounds using the organomagnesium halide complexes prepared
in hydrocarbon solvents. This method could offer advantages
over the known methods of preparation described below:
1. Preparation by the action of the classical Grig-
nard reagent on beryllium chloride. This is the most com-
monly used method for the preparation of dialkylberyllium
compounds.
8
2RMgX + BeCl2 ---+ R2 Be + MgX2 + MgCl22. Metallic beryllium can be reacted with organo-
mercury compounds. Dimethyl, diphenyl, and di-p-
tolylberyllium have been prepared by this method (6).
R2Hg + Be -4 BeR2 + Hg
The first method described is a very effective method
for preparing organoberyllium compounds. For the preparation
of pure organoberyllium compounds, this method has one main
disadvantage, since all the known organoberyllium compounds
retain ether with great tenacity. An example of the difficulty
of the removal of ether was related by Coates (7). He reported
that a diisopropylberyllium preparation which had twice been
distilled and pumped in vacuum for two days was found, upon
hydrolysis, to have retained 16 per cent by weight of ether.
The second method has several undesirable characteristics.
The main disadvantage is the amount of time required to carry
out this preparation. Although they are expensive, some organo-
mercury compounds may be purchased. If it is necessary, these
compounds may be prepared from Grignard reagents; however, the
synthesis is very time consuming.
The method of preparation of organoberyllium compounds
from organomagnesium halide complexes in benzene solvent
should be superior to the methods now used to prepare organo-
beryllium compounds. The main advantages will be that ether
is not required as a solvent and only the organomagnesium
9
halide complex and beryllium chloride are needed for the
reaction. The preparation of an ether-free organoberyllium
compound will be very beneficial in studying the properties
of organoberyllium compounds.
CHAPTER BIBLIOGRAPHI
1. Ashby, E. C., "Proof for the RMgX Composition of Grig-nard Compounds in Diethyl Ether. RMgX, the InitialSpecies Formed in the Reaction of RX and Mg," Journalof the American Chemical Society, LXXXVII (1965),25U9.
2. Ashby, E. C. and W. E. Becker, "Concerning the Structureof the Grignard Reagent," Journal of the AmericanChemical Society, LXXXV (1963), 118.
3. Ashby, E. C. and Martin B. Smith, "Concerning the Structureof the Grignard Reagent. II. In Diethyl Ether. Rele-vance of Grignard Composition to the Mechanism ofAddition to Ketones," Journal of the American ChemicalSociety, LXXXVI (1964), 4363.
4. Bryce-Smith, D., "Unsolvated Organomagnesium Complexes,"Bulletin de la Societe Chimgue de France, VII (1963),1418.
5. Bryce-Smith, D. and G. F. Cox, "Organometallic Compoundsof Group II. Part III. Unsolvated OrganomagnesiumHalides," Journal of the Chemical Society (1961), 1175.
6. Coates, G. E., Organo-Metallic Compounds, London, Methuenand Company, Ltd., 197.
7. Coates, G. E. and F. Glockling, "Diisopropylberylliumand Some Beryllium Hydrides," Journal of the ChemicalSociety (1954), 22.
8. Dessy, R. E., G. S. Handler, J. H. Wotiz, and C. A.Hollingsworth, "The Constitution of the Grignard Re-agent," Journal of the American Chemical SocLXXIX (1957), T47.,
9. Dessy, R. E. and G. S. Handler, "The constitution ofthe Grignard Reagent," Journal of the American ChemicalSociety, LXXX (1958), 5826.
10. Grignard, V., "Sur les conbinaisons organmagnesiennesmixtes et leur application a des syntheses d'acides,d'alcools et d'hydrocarbures," Annales de Chimie,XXIV (1901), 433.
10
11
11. Jolibois, M. Pierre, "Sur la formule du derive organo.-magnesien et sur l t hydrure de magnesium," ComptesRendus Hebdomadaires des Seances, CLV (1912, 357.
12. Rochow, Eugene,G., Dallas T. Hurd, and Richard N.Lewis, The Chemistry of Organometallic Compounds,New York ,JohnWiley an~d S-nsInc. 1957
13. Snow, A. I. and R. E. Rundle, "The Structure ofDimethylberyllium," Acta Crystallographic, IV (1950),348.
14. Stucky, G. D. and R. E. Rundle, "The Structure ofPhenylmagnesium Bromide Dietherate and the Natureof Grignard Reagents," Journal of the American ChemicalSociety, LXXXV (1963), 1002.
15. Vreugdenhil, A. D. and C. Blomberg, "The Constitutionof the Grignard Reagent," Recueil Des TravauxChimiues Des Pays-Bas, LXXXII (19J453
16. , "The Constitutionof the Grignard Reagent Part II," Recueil DesTravaux Chimiue Des Pays-Bas, LXII(7193T, 461.
17. Zakharkin, L. I., 0. Y. Okhlobystin, and B. N. Strunin,"Organomagnesium Compounds from Magnesium and AlkylHalides in Hydrocarbon Medium," Tetrahedron Letters,XIV (1962), 631.
18."Use of Organomagnesium Compounds for the~Synthesis ofOrganic Derivatives of Group II-V Elements in a Non-etheral Medium," Akademiia Nauk USSR. Bulletin of theAcademy of Sciences of the USSR, Division of ChemicalScience (1962),791T37
CHAPTER II
EXPERIMENTAL PROCEDURE
Materials
The magnesium metal used for the preparation of the
organomagnesium halide compounds was purchased from Fisher
Scientific Company. It was described as purified, 100-120
size magnesium metal. A highly purified sample of magnesium
metal, used in the preparation of di-n-pentylmagnesium, was
donated by the Dow Chemical Company. An impurity analysis
of this magnesium yielded the following impurities:
TABLE II
IMPURITY ANALYSIS OF MAGNESIUM
Metal Impurity Percentage
Al -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. . -. -. 0.003Ca .- .- .- .- .- .- .- .- .- .- .- .-.-.-.-.-.-.-.-.- .. - - -. . 0.01Cu . . ..-..-.-..-..-...-.... . . . . . . . 0.001
Fe . . . . . . . . . . . . . - . . . . - - . - - - - 0.0005Mn . . . -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. . 0.001Sn . . . . -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. -. . 0.01Zn .- .- .- .- .- .- .- .- .- .- .-.-.-.-.-.-.-.-.- .. - - -. . . 0.01
The sample was used in the form of fine turnings.
The n-pentyl halides used for the preparation of the
n-pentylmagnesium halide compounds were purchased from
Eastman Chemical Company. They were analyzed for purity by
gas chromatography and in each case were found to be>99 per
cent pure.
12
13
The benzene solvent utilized in these studies, described
as thiophene free, was purchased from Fisher Scientific Company.
Prior to use, the benzene was dried by distilling it from
lithium aluminum hydride onto molecular sieve. Other solvents
used in various applications were also purchased from Fisher
Scientific Company and treated in the same manner before use.
The beryllium chloride, obtained from Brush Beryllium
Company, was reputed to be 99.8 per cent pure. It was in a
powder form.
Preparation and Analysis of theOrganomagnesium Halides
A half mole preparation of the organomagnesium halide
compound is carried out using a five hundred milliliter,
three neck round bottom flask equipped with standard taper
24/40 ground glass joints. This is equipped with a Hirsch-
berg stirrer in a Teflon Asco stirring gland which seals
with Neoprene rubber o-rings. A 100 milliliter cylindrical
separatory funnel with pressure equalizing line is used in
one neck for addition of the organic halide. A system of a
nitrogen gas inlet connected by standard taper 24/40 joint
to another larger separatory funnel which is stacked upon
a Hopkins condenser fills the third neck of the reaction
flask. The larger separatory funnel is used to store the
solvent. The reaction flask is heated by a Glascol mantle
controlled by a rheostat.
14
The first step in the procedure for preparing these
compounds is to add the required amount of magnesium metal
to the flask, and begin stirring at a rate of approximately
one half a revolution per second. Heat and nitrogen flush
are then applied. To insure that the reaction flask is dry
it is heated to approximately 125 degrees centigrade. After
the system has cooled to a temperature described as "just
hot to touch," the organic halide and the solvent are added
to the two dropping funnels. Then a slight nitrogen pres-
sure is applied to the system.
At this point the reaction is initiated by the addition
of 5 to 10 per cent of the organic halide. After smoking
and refluxing of the excess organic halide is noted as
visual evidence of reaction, the remaining organic halide
is added dropwise. Heating is controlled by the rheostat to
the temperature described above. Addition of the organic
halide is usually completed in a time period of three to four
hours.
As the reaction nears completion, the contents of the
flask will form a "mud" consistency. At this point heating
is continued and the stirring is increased to a vigorous
rate for an additional hour. The solvent is then introduced
and the heating controlled to gain a slow reflux of the
solvent. The reflux condition is continued for another two
hours.
15
The reaction product is taken into the dry box and
transferred to a one liter bottle fitted with a 24/40
standard taper joint. Next a plug is wired into the top
of the bottle and the system is then centrifuged. This
step is essential due to the fact that the liquid phase of
the reaction mixture is so viscous that the "mud" phase
will not settle out. The centrifuging is carried out at a
speed of 2100 revolutions per minute for a period of three
to six hours. The viscosity of the solution is the deter-
mining factor for the time required to separate the two
layers. After this is accomplished the bottle is taken
back into the dry box and the liquid layer filtered through
a medium fritted filter. A water white filtrate is always
obtained for the n-pentylmagnesium chloride, bromide, and
iodide compounds. Some of the arylmagnesium halide compounds
yield pale yellow filtrates.
A competing coupling reaction takes place in this
procedure along with the organomagnesium halide compound
formation. After the reaction is completed, the removal of
the coupling product is effected by evaporating the solvent
from the filtrate by means of a vacuum pump. Throughout this
procedure heat is applied to warm the solution for ease of
evaporation. After a state of dryness has been reached, both
pumping and warming are continued for approximately a half
hour to an hour depending upon the amount of coupling product
16
found in a previous analysis. Next, benzene solvent is re-
added to the flask to bring the solid organomagnesium halide
compound back into solution. In the case of n-pentylmagnesium
compounds, only a minute amount of solid did not dissolve after
evaporation.
The coupling product found in the n-pentylmagnesium
halide system is decane. Analysis for decane is made by
gas chromatography using a fifteen foot silicone column
(SE-30) at a temperature of 120 degrees centigrade and a
helium carrier gas flow rate of one milliliter per second.
The analysis is carried out using an instrument which con-
tains a thermal conductivity detector.
In order to determine the amount of magnesium that
exists as the organomagnesium halide form, an analysis of
the purified solution is made. This is accomplished by
first determining the total hydroxide concentration produced
upon hydrolysis of an aliquot of the solution. This analysis
is made by a standard titration method using phenophthalein
indicator. An analysis of the hydrocarbon from another
hydrolyzed aliquot of the solution by gas chromatography
determines the concentration of the organic part of the
organomagnesium halide compound which was bound to the
magnesium atom. From these two analyses the yield of mag-
nesium existing as organomagnesium halide can be obtained.
To complete the analysis of this solution a determination of
17
the concentration of the halide species is made. This is
done by a potentiometric titration method from a hydrolyzed
aliquot of the solution. Standardized silver nitrate is
employed with a potentiometric analysis system consisting of
a silver--silver chloride, and a calomel electrode connected
to a voltage meter. From these analyses a stoichiometric
determination can be made of the organomagnesium halide
species existing in the benzene solvent.
Cryoscopic Molecular Weight Determination
The apparatus used in making cryoscopic measurements
on solutions of organomagnesium halide compounds in benzene
solvent is shown in Figure 1. The apparatus shown in Figure 1
consists of a piece of twenty millimeter tubing two inches
long, sealed at one end. The other end consists of an outer
24/40 standard taper ground glass joint and a side arm ex-
tending from beneath this joint. The side arm is attached to
a three way standard taper stopcock. The function of the side
arm is to admit a nitrogen atmosphere throughout the measure-
ment. A mercury filled thermowell is used to provide a thermal
contact from the solution to the thermistor. The thermistor
is connected to a Leeds and Northrup ten millivolt recorder
which serves as a null-point indicator for the thermistor
bridge. The thermistor sensitivity is 0.001 degrees centigrade.
A solvent freezing point depression may be duplicated toi0.006
degrees centigrade. The freezing point of a solution may be
THERMISTOR
ASCO GLAND
TO
SOLUTION
o
'4
18BALANCE BRIDGEAND RECORDER
NITROGEN
THREE WAYSTOPCOCK
THERMOWEL LCONTAININGMERCURY
FIGURE I. MOLECULAR WEIGHT APPARATUS
t
19
duplicated to 0.02 degrees centigrade. The thermowell is
held into the system by a Teflon Asco stirring gland which
seals the nitrogen atmosphere into the system with Neoprene
o-rings. This stirring gland also allows the thermowell to
be rotated. Glass tips welded onto the thermowell provide
agitation of the solution as the thermowell is rotated.
Better freezing point data duplication of the solvent is
aided by wrapping the outside of the apparatus with a film of
plastic insulation.
The procedure employed in making freezing point deter-
minations is to load the above described apparatus with a
sample of benzene solvent. The system is then immersed to the
level of the side arm in an ice water solution contained in a
Dewar flask. The thermowell is rotated as the bridge is con-
tinually balanced until the freezing point of the solvent is
detected. This gives a freezing point reading of the solvent
on the bridge.
Next the apparatus is cleaned and taken into the dry box
and loaded with a solution containing the organomagnesium
halide compound. The same procedure employed with the solvent
is then repeated under nitrogen atmosphere to determine a
reading for the freezing point of this solution. From these
two readings a freezing point depression can be determined
for the solution.
20
Knowing the densities of the solvent and the solution
to be equivalent, the concentration of the solution containing
the organomagnesium halide compound and the freezing point
depression produced by this solution, then, the molecular
weight of the organomagnesium halide species can be determined
from the following expression:
M2 = Kf 2 1000Tf Wi
M2 molecular weight of the solute
Kf molal freezing point constant for the solventemployed
Tf freezing point depression
w2 grams of solute
w, grams of solvent
From the data of molecular weight in the solution and the
stoichiometric molecular weight the degree of association can
be determined.
Preparation and Analysis ofDi-n-pentylmagnesium
Di-n-pentylmagnesium was prepared in the absence of
ether solvent in order that its solubility in benzene solvent
could be determined. The general procedure used in this
synthesis is first to prepare di-n-pentylmercury, and then to
carry out a metal exchange reaction between the di-n-pentylmercury
and magnesium metal in benzene solvent.
21
Di-n-pentylmercury is prepared by the action of mercuric
chloride on n-pentylmagnesium bromide in a large volume of
ether. The mercury chloride is introduced into the reaction
vessel with a Soxhlet extractor (1). After the required
amount of mercury chloride is added, a large portion of the
ether solvent is distilled away from the reaction mixture
while it is still being stirred. Upon completion of the
distillation, the ether is readded to the reaction flask.
The excess Grignard reagent is then removed by hydrolyzing
the reaction and separating the water layer from the ether
layer. Di-n-pentylmercury is recovered from the ether solution
by vacuum distillation. The conditions required to distill
the mercury compound are 139 degrees centigrade and 15.5 mm
mercury pressure.
Synthesis of the di-n-pentylmagnesium (2) consists of
stirring a solution of di-n-pentylmercury and benzene with
purified magnesium turnings. This exchange reaction's rate
can be increased by warming the reaction. As the reaction
proceeds, the solution becomes very viscous. The stirring
time required for this reaction to reach 70 per cent com-
pletion is one month, at a temperature of 35 degrees centi-
grade.
A Varian A60 nuclear magnetic resonance spectrometer is
used to monitor the extent of reaction in the synthesis of
the di-n-pentylmagnesium. Utilization of the alpha-methylene
22
triplet at delta = 1.35 ppm with respect to tetramethyl
silane standard was the primary absorption employed in
monitoring the reaction. Spectra of the starting material
and of a n-pentylmagnesium chloride preparation are used to
evaluate the limits of this reaction. After a nuclear magnetic
resonance spectrum of the reaction mixture shows little charac-
teristics of the di-n-pentylmercury spectrum the reaction is
stopped.
Obtaining a solution of di-n-pentylmagnesium from the
reaction mixture is complicated by the suspended magnesium
amalgam in the very viscous reaction solution. This reaction
solution must be filtered to eliminate the suspension; how-
ever, it cannot be diluted because of the desire to study
the solubility of the di-n-pentylmagnesium in the benzene
solvent employed. After enough of the mixture has been
filtered to enable analysis to be made, the stoichiometry
and molecular weight of the species in solution is determined
by using the same procedure described in the second section
of this chapter.
Determination of the yield of di-n-pentylmagnesium in the
solution is made in two ways. First the amount of di-n-
pentylmagnesium produced is determined by the procedures
described earlier. The other method is to determine the
actual mercury content remaining in solution by a spectro-
graphic procedure utilizing the 2536A emission of sparked
23
mercury. Densitometer readings are made of the intensities
of the lines from the spectrographic plates and from this data
an intensity-concentration graph is constructed.
Preparation and Analysis of Organo-beryllium Compounds
The apparatus used in the synthesis of the organo-
beryllium compounds consists of a round bottom flask fitted
with a Hirschberg stirrer and a Teflon Asco stirring gland.
The reaction between beryllium chloride and the organomag-
nesium halide compound is carried out by vigorously stirring
the mixture. The beryllium chloride is introduced into the
reaction flask by spatula before the stirring is begun. A
stoichiometric amount of beryllium chloride is used.
If the organomagnesium halide compound is soluble in
benzene, a solution of the organomagnesium halide compound
is stirred with the solid beryllium chloride. The ethyl-
magnesium halide compounds are only sparingly soluble in
benzene solvent; therefore, in effecting a synthesis of di-
ethylberyllium the beryllium chloride is stirred with a mix-
ture of solvent and the ethylmagnesium halide mud. The
reaction can be accomplished either in a dry box or outside
the dry box under a nitrogen atmosphere.
The stirring time required for the reaction to reach
completion is dependent upon the organoberyllium compound
being synthesized. It was observed in this work that the
24
formation of the non-aromatic organoberyllium compounds was
completed in twelve to fifteen hours whereas the aromatic
organoberyllium compounds required twenty-four to thirty hours
of stirring time. Application of heat to increase the rate
of these reactions was not used due to the instability of
the organoberyllium compounds at elevated temperatures.
Determination of the concentration of the organoberyllium
compound prepared by the described technique is made by two
methods. One method is to determine the amount of beryllium
in solution by the ring oven technique (4). The second method
is to determine the concentration of the alkyl or aryl portion
of the organoberyllium compound. This analysis is made either
by gas chromatography for the alkyl or aryl hydrocarbon species
which remain in solution upon hydrolysis or by gas volume
measurements for the alkyls which form gases upon hydrolysis.
To apply the first two analytical techniques, aliquots of the
solution containing the organoberyllium compound are pipetted
into volumetric flasks. These solutions are then hydrolyzed
and acidified. Water is added until the water layer reaches
the volumetric marking. The hydrocarbon layer is then removed
for gas chromatographic analysis. The remaining water layer
is used for the ring oven analysis. If the organoberyllium
compound being hydrolyzed contains a short chain alkyl group,
the solution is cooled in ice water before hydrolysis is car-
ried out, since shorter chain dialkylberyllium compounds
25
react very violently with water. However, if the organo-
beryllium compound contains an aryl hydrocarbon portion,
after water is added to the solution it must be shaken vig-
orously to get the beryllium into the water layer.
Diethylberyllium yields a gas composed essentially of
ethane when it is hydrolyzed. Figure 2 shows the apparatus
used to hydrolyze a solution of diethylberyllium and to
measure the volume of gas evolved. The procedure used is to
load the diethylberyllium solution into (A), the apparatus
enclosed by the dotted lines in Figure 2. This is done in
the dry box. This piece of apparatus is then brought out
and connected to the gas burette and vacuum manifold. Next
the gas burette and vacuum manifold are flushed with nitrogen
and checked for leaks. In succeeding steps the ampule con-
taining the water (B) is placed into position and the entire
system is adjusted to atmospheric pressure. Next the system
is isolated from the vacuum manifold and the gas burette.
Liquid nitrogen is used to freeze the solution containing
beryllium. After the solution is frozen the ampule containing
water is inverted and the water is added to the frozen solution.
Warming of the solution is controlled slowly until a pressure
of evolved gas is obtained. The system is then opened to the
gas burette and the volume of gas evolved is measured. Next
the solution is slowly stirred by means of a Teflon coated
magnetic stirring bar which is contained in the solution.
VACUUM.MANIFOLD
THREE WAY
WATER STOPCOCK
B
CLAMP
SOLUTION-4-
L
MERCURYLEVELINGBULB
GASBURETTE
A
HYDROLYSIS APPARATUS
26
TO NITROGEN
I
~~~
1*44mommumommomm
FIGURE 2.
27
Determination of the content of the gas evolved is made by
using gas chromatography. A fifteen foot silica gel column
is used for this analysis. The hydrocarbon portion of this
gas is detected in a stream of helium carrier gas, and the
hydrogen gas content is detected using nitrogen carrier gas.
The gas chromatograph being used is equipped with a thermal
conductivity detector.
The determination of molecular weights of the organo-
beryllium compounds is carried out in the same manner as
described for the organomagnesium halide compounds. Benzene
is used as the solvent for these organoberyllium compounds.
Infrared Absorption Studies
A Perkin-Elmer Model 21 spectrophotometer is employed
to study the absorption frequencies of the organomagnesium
halide complexes, di-n-pentylmagnesium, di-n-pentylmercury,
and organoberyllium compounds synthesized in this work. The
absorption frequencies were observed in the region between
fifteen and twenty-five microns. This required cesium bromide
optics which were used in this study.
The procedure used to obtain this data is first to flush
the spectrophotometer with nitrogen gas. A scan of cyclo-
hexane is run for calibration purposes. The absorption fre-
quency used for calibration purposes is 19.07t.02 microns (3).
Next, solutions were loaded into 0.25 millimeter path length
28
cells in the dry box. These cells were then brought out of
the dry box and spectra of the solutions obtained.
CHAPTER BIBLIOGRAPHY
1. Gilman, Henry and Robert E. Brown, "The Preparation ofMercury Dialkyls from Organomagnesium Halides," Journalof the American Chemical Society, LII (1930), 331
2. Schlenk, W., "Magnesiumdialkyle and Magnesiumdiaryle,"Berichte der Deutschen Chemischen Gesellschaft, LXIV
3. Stewart, James E., "Infrared Spectra of Solvents in thePostassium Bromide Region," Beckman Scientific andProcess Instruments Division Appicati--~s
4. West, Philip W. and Patricia R. Mohilner, "Estimationof Beryllium with Eriochrome Cyanine R Using theRing Oven Technique," Analytical Chemis XXIV(1962), 558.
29
CHAPTER III
RESULTS AND DISCUSSION
In Chapter I a summary was given of what is known about
the molecular structure of organomagnesium halide compounds
in hydrocarbon media (3) and in higher dielectric media such
as ether, tetrahydrofuran, and triethylamine (1, 2). From
this discussion it is evident that the elucidation of the
molecular structure of organomagnesium halide compounds is
more complete for the higher dielectric solvents than for
hydrocarbon solvents. Therefore, the purpose of this work
is to gain a more complete insight into the molecular structure
of the organomagnesium halide compounds which exist in hydro-
carbon solvent.
In review, Bryce-Smith and co-workers (3) determined
that the empirical formula R3MgX is representative of some
solutions of "butylmagnesium iodide" in isopropylbenzene and
tetrahydronaphthalene, although relative viscosity studies
suggested higher molecular weights. Bryce-Smith also reported
that a low degree of solubility was characteristic for the
methyl, ethyl, and n-propylmagnesium halide compounds in these
solvents. In order to secure a more complete description of
the molecular structure of the organomagnesium halide compounds
in a hydrocarbon medium, an extension of this work seems necessary.
30
31
The system chosen for study was the n-pentylmagnesium
halides in benzene solvent. Benzene was chosen as the
solvent so that molecular weight measurements could be done
cryoscopically. The n-pentylmagnesium halide compounds
were selected due to expected increase in solubility and
because they had not been studied.
The data obtained in an attempt to elucidate the
molecular structure of these n-pentyl-agnesium halide
compounds in benzene solvent is summarized in Table III.
TABLE III
ANALYSIS OF n-PENTYMAGNESIUMIN BENZENE SOLVENT
COMPOUNDS
Alkyl Halide RatioHalide Molari MolarX Association
Chloride 0.434 . . . . . 1.80.348 0.003 116 2.10.130 . . . . . 2.2
Bromide 0.255 0.0158 16.1 5.1
0.513 0.035 14.6 4.5
0.320 0.026 12.3 7.60.290 0.023 12.6 8.40.185 0.015 12.3 8.3
0.36 0.0200 18.0 5.20.244 0.0136 17.9 4.80.153 0.0084 18.2 4.1
Iodide 0.438 0.095 4.6 . .0.208 0.041 5.1 . .0.077 0.015 5.1 . .
0.580 0.118 4.9 . .
Di-n-pentyl-magnesium* 0.076 0.0007 109 2.0
*No halide species present in this compound
32
This data reports the characteristic ratio of the alkyl
to halide concentration for the species being studied, as
well as the degree of association. This is reported over a
concentration range in order to determine whether there is
any variation in the degree of association with concentration,
since this effect was noted by Ashby (1) for the organomag-
nesium halide compounds in ether solvent.
The data from Table III demonstrates that the degree of
association in benzene solvent varies only slightly upon
changing the concentration and is dependent upon the halide
species studied. This effect will be discussed in detail
for each halide in following paragraphs. The data also
gives evidence that the n-pentylmagnesium halide species
in benzene solvent are characterized by polymeric structures,
and the degree of association or polymeric character is
primarily dependent upon the halide being studied. The
degree of association decreased in the order iodide >
bromide > chloride. It is evident from the data that the
n-pentylmagnesium chloride compound in solution cannot
really be classified as an n-pentylmagnesium chloride com-
pound; it is essentially di-n-pentylmagnesium.
The solubility data in the literature indicates that
di-organomagnesium compounds are insoluble in hydrocarbon
solvents (6). Bryce-Smith (3) found di-n-butylmagnesium
to be effectively insoluble in isopropylbenzene. In order
33
to be able to explain the results observed in Table III,
di-n-pentylmagnesium must be soluble in benzene solvent.
To verify this conclusion, di-n-pentylmagnesium was synthe-
sized and yielded a very viscous benzene solution. A solution
of 0.28 normality was obtained. Therefore, it may be con-
cluded that although di-n-butylmagnesium was reported to be
insoluble in isopropylbenzene solvent, the di-n-pentylmagnesium
compound is soluble in benzene solvent.
A molecular weight study of the solution of soluble di-
n-pentylmagnesium demonstrated that this speciesexists as a
dimer in benzene solvent. This data provides conclusive
evidence that the species classified as the n-pentylmagnesium
chloride is really di-n-pentylmagnesium.
An exchange reaction between magnesium metal and di-n-
pentylmercury was employed for the synthesis of the di-n-
pentylmagnesium compound. This reaction was monitored using
a Varian A60 nuclear magnetic resonance spectrometer. This
monitoring was employed to observe the disappearance of the
alpha-methylene triplet of the di-n-pentylmercury compound.
The absorption of this alpha-methylene triplet was observed
at delta = 1.35 ppm with respect to tetramethylsilane
standard (4). Figure 3 shows NMR absorption spectra of the
reaction mixture as a function of time. The Mah absorption
(A) is an illustration of the di-n-pentylmercury absorption
pattern with tetramethylsilane as internal standard. Absorption
-2
(A) STANDARD
di-n-penty r mercury
(B) STANDARD
n-pentylmognesium
FIGURE 3. NUC
-I Pp-- (C5HII)Mg +Hg
-2 - ppmM 0
(C 5 1)2 Hg + Mg'"S o
(C)
(D)
(E) ,M~
Hxl(F)
(G)-
chloride
LEAR MAGNETIC RESONANCE MONITORING OF THEDI-N- PENT YLMAGNESIUM 'SYNTHESIS
34
I
7
DAYS
21
23
27
-30
I
35
pattern (B) demonstrates the n-pentylmagnesium chloride NMR
absorption in relation to the benzene solvent standard. Ab-
sorption patterns (C) through (G) illustrate the formation of
the di-n-pentylmagnesium compound.
The data in Table III demonstrates that the n-pentyl-
magnesium iodide compound exhibited an alkyl to halide ratio
of approximately five. This ratio remained effectively con-
stant upon dilution of the solution even though a small
amount of disproportionation was observed. These species
yielded molecular weight values greater than could be ac-
curately measured by the method applied. From the data
obtained the only conclusion that can be drawn is that the
species in solution demonstrated a higher association value
than either the n-pentylmagnesium chloride or bromide species.
The n-pentylmagnesium bromide compound in benzene
solvent demonstrated an alkyl to halide ratio magnitude which
ranged from twelve to eighteen. Table III shows that the
variation in the molecular weight values parallels the vari-
ations in alkyl to halide ratio values for the different
n-pentylmagnesiumn bromide preparations. The variation of
association upon dilution observed for these preparations
was small and also appeared to be dependent upon the alkyl to
halide ratio. In addition, there was no evidence of dispro-
portionation upon dilution as was evidenced in the n-pentyl-
magnesium iodide system. Several solutions of n-pentylmagnesium
36
bromide showed no evidence of disproportionation after stand-
ing for as long as two months.
Evidence from studies by Ashby (1) showed the chloride
to be a better bridging agent than either the bromide or
the iodide. The data demonstrated in Table III seems to
contradict such a statement. However, in order to explain
the data in Table III the following effect is proposed.
Upon preparation of the n-pentylmagnesium halide compounds
equilibrium (a) is predicted to exist; however, when solvent
is added to this preparation and the n-pentylmagnesium halide
compound goes into solution, then equilibrium (b) is estab-
lished.
(a) (RMgX) ;; MgX 2 + Rkmgk+p I"
2
(b) "RkMgk+XP" i tT "RMgq45Xs " ."RtMgt+uXu"2 2
The species (RMgX)j is an associated species formed on the
surface of the magnesium metal which is capable of dispro-
portionating to yield MgX2 and another species "RkMgk+pXp"
with a variable amount of R and X depending upon what R and X
species is being described. In solution this "RkMgk+pXp" is
capable of disproportionation into two new species represented
as "RqMg 4 5 Xs" and "RtMgttuXu." One of these species is be-
lieved to be alkyl rich and the other halide rich. Using this
proposal, the results of Table I can be explained in tID fol-
lowing manner. Since it is observed that the chloride species
37
in solution has effectively no chloride character, the
equilibrium (a) is predominantly driven to the right in
preparation. This then yields MgCl2 and the "RkMgk+pXp"
consists primarily of di-n-pentylmagnesium. However, in the
case of the bromide and the iodide species, equilibrium (a)
is not driven to the right so extensively as in the case of
the chloride, and the species represented as "RkMgk+pXp" or
(RMgX)j allows equilibrium (b) to be established.
At this point an explanation is offered for the fact that
tipon dilution, disproportionation is observed for the iodide
species and not for the bromide species in solution. The
iodide species which exist in solution exhibit a much higher
association character than the bromide species; therefore,
upon dilution equilibrium (b) is driven to the right, and for
the iodide system a higher concentration of the halide rich
species is formed. The solubility limit of the iodide rich
species is then exceeded and a precipitation is observed.
Upon disproportionation the bromide system, which exhibits a
much lower association character than the iodide system, does
not yield a very high concentration of the bromide rich species;
therefore, the solubility limit for this species is not ex-
ceeded.
The molecular structure of the Grignard reagent has been
reported (1, 2) to be dependent upon halide, organic radical,
and solvent. In an attempt to gain some insight into the
38
effect of the organic portion of the organomagnesium halide
molecular structure in benzene solvent, the data in Table IV
was obtained.
TABLE IV
MOLECULAR STRUCTURE DEPENDENCE UPON THE ORGANICPORTIONS OF ORGANOMAGNESIUM HALIDE
COMPOUNDS IN BENZENE SOLVENT
Organic Halide ~Organic (moles/ Halide (moles/ Ratio Associ-Species liter) Species liter) ation
Tolyl 0.100 Chloride 0.02 5 1.8
Phenyl 0.150 Chloride 0.011 14 0.8
n-Pentyl* 0.348 Chloride 0.003 100 2.1
Ethyl** . . . . .
*This data from Table III
**Not soluble in benzene solvent
This data, although not a complete study, provides
evidence that the organic portion of the organomagnesium
halide compound in benzene solvent has a very definite ef-
fect upon the molecular structure. The arylmagnesium chloride
compounds studied demonstrate that the species in solution can-
not be described as a diorganomagnesium compound as was ob-
served for the n-pentylmagnesium chloride compound. Table IV
also demonstrates that the ethylmagnesium halide compounds
are not soluble in benzene solvent. Therefore, the effect of
39
the organic portion of the organomagnesium halide compounds
upon the molecular structure seems evident.
The synthesis of organoberyllium compounds from organo-
magnesium halide compounds in benzene solvent proved to be
an effective method. Table V tabulates the data obtained
using this method for synthesizing organoberyllium compounds.
Data obtained in association studies is also included in this
table.
The reason for the low yield exhibited by the diethyl-
beryllium preparation is explained by the fact that ethyl-
magnesium iodide has proved to be a very difficult compound
to prepare in a high yield. Furthermore, since ethylmagnesium
halides are only slightly soluble, the reaction between beryl-
lium chloride and the "mud" from the preparation of ethyl-
magnesium iodide is characterized as a reaction between two
solid phases, and would be expected to occur with difficulty.
This effect is also demonstrated in the low yield obtained
for the di-n-butylberyllium preparation. The synthesis of
ditolylberyllium is a reaction carried out between solid
beryllium chloride and a solution of tolylmagnesium chloride,
and this reaction readily gives high yields. The data of
Table V demonstrates that the preparation of organoberyllium
compounds by this method is more effective for organomagnesium
halide species which are soluble in benzene solvent. The data
also reveals that the organoberyllium compounds characterized
0
'H
( 10
01co02
C\J0
**
. H
**
*4O Lrn 0 LIT 0 (\
H ,
OH0 -- 0 Ln\ : C4 J+, C\, n \j C-) co C\J
Hc H-Hr-H4 0 C)H
0000
So cem 2~CMiCM Hc H GD H . C.to L5 .0t r..aSH' [oC H 00 -it
0
0
0C)
5,'
H
H
40
-HH
H-H
' 0 H
-P P o0 o0 H
H H0I I H 0z 0 4I I +e a
.*H .H .*- .rHq q q q
I
40
CD
co0H(OH0COO
pq
r400
H c;
O 0
HO
-H
.r-
4
0
0
rd
C
ra
coaQ)
0
CH
'H
0
A r
--
H4c
0
rH
-P
ao0
.P
0
02
.S
02
0cH
0
0P4
02I
41
by large organic species exist as monomers in benzene
solvent.
The data obtained from the infrared absorption studies
of the compounds synthesized is tabulated in Table VI. An
illustration of the absorption spectra for the n-pentyl-
magnesium halide compounds and di-n-pentylmagnesium is
shown in Figure 4. In view of the comparatively low halide
content of these solutions, the similarity of their spectra
in this twenty micron region is not surprising. As can be
seen in Figure 4, the shapes of the absorptions did appear
to broaden as the halide content increased in the order
Cl Br I.
The infrared absorption data reported in Table VI
was obtained for solutions of these compounds in benzene
solvent. The characteristic C-Ig-C absorption was observed
between 545 and 550 wave numbers. This represents a shift
to higher frequencies of thirty wave numbers compared to
diethylmagnesium in diethyl ether (7). This shift may be
interpreted in terms of a more polar carbon-metal bond in
strongly coordinating solvents (8). This effect is also
seen from the data in Table VI in the absorption shifts
measured by n-pentyl, tolyl, and phenyl compounds. The
C-Hg-C absorption is reported to demonstrate additional
evidence that the di-n-pentylmagnesium preparation formed
WAVE NUMBER (cm-1)
550 500
III
421450
(C 5 HII )2 Mg0.077 N
0.25 N
"Br "
O.I5 N
"I "I
0.23 N
I I15 17 19 21
WAVE LENGTH (microns)
FIGURE 4q INFRARED SPECTRA OF -PENTYLMAGNESIUM HALIDE COMPLEXESIN BENZENE
23
600
wz
Ul)z
I
43
TABLE VI
INFRARED ABSORPTIONS
Compound Absorption (cm-1 )
n-pentylmagnesium iodide . . . . . . . . . . . . . 545n-pentylmagnesium bromide . ...... . . . . 547n-pentylmagnesium chloride . . . . . . . . . . . . 548di-n-pentylmagnesium . . . . . . . . . . . . . .0.*549di-n-pentylmercury . . . . . . . . . . . . . . . 515phenylmagnesium chloride . . . . . . . . . . . . . 430tolylmagnesium chloride . . . . . . . . . . . . . 549
484*diethylberyllium . . . . . . . . . . . . . . . . . 505
di-tolylberyllium . . . . . . . . . . . . . . . . 502
465*diphenylberyllium . . . . . . . . . . . . . . . . 442
*This absorption is a characteristic absorption ofthe tolyl portion of the species reported.
a new species which can be characterized by infrared
spectroscopy to exhibit the C-Mg-C absorption frequency.
The infrared absorption frequencies for the organoberyllium
compounds were observed in the range of 500 to 505 wave
numbers.
According to the harmonic oscillator approximation the
infrared absorption frequencies would increase in the order
C-Hg-C < C-Mg-C ( C-Be-C if mass effects predominated.
Table VII gives values of masses and electronegativity values
(5) for the elements concerned. The force constants in the
harmonic oscillator approximation will be affected by a change
in electronegativity values for each element. The greater
the attraction between a metal element and an organic radical,
44
TABLE VII
ELECTRO\EGATIVITY AND MASS VALUES
Element Mass (grams/moles) Electronegativity
Be 9.0 1.47
Mg 24.3 1.23
Hg 200.6 1.44
the larger the force constant value will be. This effect
must be large enough to explain the order of absorption
frequencies observed in Table VI. This order of absorption
frequency values is seen to be C-Mg-C > PC-Hg-C > C-Be-C.
CHAPTER BIBLIOGRAPHY
1. Ashby, E. C., "Proof for the RMgX Composition ofGrignard Compounds in Diethyl Ether. RMgX, theInitial Species Formed in the Reaction of RX andMg," Journal of the American Chemical Society,LXXXVII (1965T, 279.
2. Ashby, Eugene C. and Martin B. Smith, "Concerning theStructure of the Grignard Reagent. III. In DiethylEther. Relevance of Grignard Composition to theMechanism of Addition to Ketones," Journal of theAmerican Chemical Society, LXXXVI (1964,"433.
3. Bryce-Smith, D. and G. F. Cox, "Organometallic Compoundsof Group II. Part III. Unsolvated OrganomagnesiumHalides," Journal of the Chemical Society (1961), 1175.
4. Dessy, Raymond E., T. J. Flautt, H. H. Jaffe, and G. F.Reynolds, "Nuclear Magnetic Resonance Spectra of SomeDialkylmercury Compounds," Journal of Chemical Physics,XXX (1959), 1422.
5. Rochow, Eugene G., Organometallic Chemistry, New York,Reinhold Publishing Corporation, 1964.
6. Rochow, Eugene G., Dallas T. Hurd, and Richard N. Lewis,The Chemistry of Organometallic Compounds, New York,John Wiley and Son, Inc., 1957.
7. Salinger, R. M. and H. S. Mosher, "Infrared SpectralStudies of Grignard Solutions," Journal of the AmericanChemical Society, LXXXVI (1964), 1782.
8. West, Robert and William Glaze, "The Infrared Spectraof Alkyllithium Compounds," Journal of the AmericanChemical Society, LXXXIII (1l61),3758.
45
BIBLIOGRAPHY
Books
Coates, G. E., Organo-Metallic Compounds, London, Methuenand Company Ltd., 95.
Rochow, Eugene G., Organometallic Chemistry, New York,Reinhold Publishing Corporation, 1964.
Rochow, Eugene G., Dallas T. Hurd, and Richard N. Lewis,The Chemistry of Organometallic Compounds, New York,John Wiley and Son, Inc., 1957.
Articles
Ashby, E. C. and W. E. Becker, "Concerning the Structure ofthe Grignard Reagent " Journal of the American ChemicalSociety, LXXXV (19631, 118.
Ashby, Eugene C. and Martin B. Smith, "Concerning the Structureof the Grignard Reagent. II. In Diethyl Ether. Relevanceof Grignard Composition to the Mechanism of Addition toKetones," Journal of the American Chemical Society,LXXXVI (1964)7,4363Y
, "Concerning the Structureof the Grignard Reagent. --III. In Diethyl Ether. Relevanceof Grignard Composition to the Mechanism of Addition toKetones " Journal of the American Chemical Society,LXXXVI 1964)7, 4363T
Ashby, E. C., "Proof for the RMgX Composition of GrignardCompounds in Diethyl Ether. RMgX, the Initial SpeciesFormed in the Reaction of RX and Mg " Journal of theAmerican Chemical Society, LXXXVII 41965),O2509.
Bryce-Smith, D., "Unsolvated Organomagnesium Complexes,"Bulletin de la Societe Chimique de France, VII (1963),
Bryce-Smith, D. and G. F. Cox, "Organometallic Compounds ofGroup II. Part III. Unsolvated Organomagnesium Halides,"Journal of the Chemical Society (1961), 1175.
46
47
Coates, G. E. and F. Glockling, "Diisopropylberyllium andSome Beryllium Hydrides," Journal of the Chemical Sociey(1954), 22.
Dessy, Raymond E., T. J. Flautt, H. H. Jaffe, and G. F. Reynolds,"Nuclear Magnetic Resonance Spectra of Some DialkylmercuryCompounds," Journal of Chemical Physics, XXX (1959), 1422.
Dessy, R. E. and George S. Handler, "The Constitution of theGrignard Reagent," Journal of the American Chemical yLXXX (1958), 5826.
Dessy, R. E., G. S. Handler, J. H. Wotiz, and C. A. Hollings-worth, "The Constitution of the Grignard Reagent,"Journal of the American Chemical Society, LXXXIX (1957),3476.
Gilman, Henry and Robert E. Brown, "The Preparation of MercuryDialkyls from Organomagnesium Halides," Journal of theAmerican Chemical Society, LII (1930)9, .3314.T
Grignard, V., "Sur les combinaisons organmagnesiennes mixteset leur application a des syntheses d'acides, d'alcoolset d'hydrocarbures," Annales de Chimie, XXIV (1901), 433.
Jolibois, M. Pierre, "Sur la formule du derive organo-magnesienet sur l'hydrure de magnesium," Comptes Rendus Hebdomadairesdes Seances, CLV (1912), 353.
Salinger, R. M. and H. S. Mosher, "Infrared Spectral Studiesof Grignard Solutions "1 Journal of the American ChemicalSociety, LXXXVI (1964 , 1782.
Schlenk, W., "Magnesiumdialkyle and Magnesiumdiaryle,"Berichte .der Deutschen Chemischen Gesellschaft, LXIV
Snow, A. I. and R. E. Rundle, "The Structure of Dimethylberyllium,Acta Crystallogaphic, LV (1950), 348.
Stucky, G. D. and R. E. Rundle, "The Structure of Phenyl-magnesium Bromide Dietherate and the Nature of GrignardReagents," Journal of the American Chemical SLXXXV (1963)t 1002.
Vreugdenhil, A. D. and C. Blomberg, "The Constitution of theGrignard Reagent," Recueil Des Travaux Chimiques Des
ys-Bas, LXXXII (193)TT53.
48
Vreugdenhil, A. D. and C. Blomberg, "The Constitution of theGrignard Reagent. Part II," Recueil Des Travaux ChimiquesDes Pays-Bas, LXXXII (1963), 41.
West, Philip W. and Patricia R. Mohilner, "Estimation ofBeryllium with Eriochrome Cyanine R Using the Ring OvenTechnique," Analytical Chemistry, XXXIV (1962), 558.
West, Robert and William Glaze, "The Infrared Spectra ofAlkyllithium Compounds " Journal of the American ChemicalSociety, LXXXIII (19613, 35.
Zakharkin, L. I., 0. Y. Okhlobystin, and B. N. Strunin,"Organomagnesium Compounds from Magnesium and AlkylHalides in Hydrocarbon Medium," Tetrahedron Letters,XIV (1962), 631.
, fUseof Organomagnesium Compounds for the yntesis 0 OrganicDerivatives of Group II-V Elements in a NonetheralMedium," Akademiia Nauk USSR. Bulletin of the Academyof Sciences of the USS, Division of emcT'T~ScienceTT962) 1913.
Reports
Stewart, James E., "Infrared Spectra of Solvents in thePotassium Bromide Region," Beckman Scientific and ProcessInstruments Division A pplicationata SheetFullerton, California,-Beckman Instruments, Inc.