organic chemistry-ppt03
TRANSCRIPT
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
1/39
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
2/39
What is Organic Chemistry ?
The study of the compounds of carbon.
Some carbon compounds arenot consideredto be
organic, suchas CO2, CO, salts of carbon-
containing polyatomic ions (e.g., CO32-, CN-).
Inorganic chemistry is the study of the other
elements andnon-carbon containing compounds
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
3/39
Carbon
Carbon is unique since it can form single, double, & triple
bonds with itself and with other atoms
Carbonatoms can form stable bonds to many other
elements (H, F, Cl, Br, I, O, N, S, P, etc.). Most organiccompounds containa few hydrogens, and sometimes
oxygen, nitrogen, sulfur, phosphorus, etc.
Carbonatoms can form complex structures, suchas long
chains, branched chains, rings, chiral compounds, etc.
Because of this variety in bonding and complexity, carbon
atoms can formatremendous variety of compounds.
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
4/39
Hydrocarbon: Alkane
A hydrocarbon is a compoundconsisting of only hydrogen (H)andcarbon (C).
The carbonto carbon can be single,double , or triple bonds.
AlkanesAlkanes arehydrocarbons with onlysingle bonds.single bonds.
Alkane: saturatedhydrocarbons
(CnH2n+2) Saturated: only single bonds
They arealso calledaliphaticcompounds
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
5/39
Structure
Saturatedhydrocarbons can be:
linear (general formula CnH2n + 2)
branched (general formula CnH2n + 2, n > 3)
cyclic (general formula CnH2n, n > 2).
The former two arealkanes, whereas thethird group is called cycloalkanes.
Shape
tetrahedralabout carbon
all bondangles areapproximately 109.5
The simplestpossiblealkane (theparentmolecule) is Methane (CH4).
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
6/39
Drawing Alkanes
Whena structure is drawnto show eachbond, it is calledacomplete structuralformula (expanded structural formula).
Incondensed structural formulas, only
specific bonds are shown;this is useful inreducing the number of CH bonds thatmust bedrawn
Inline drawings (line-angle formulas),bonds are represented by lines;
everywheretwo lines meet or alinebegins or ends is a C atom. Hs on Cs arenot shown (except for emphasis). Hs onother atoms must be shown
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
7/39
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
8/39
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
9/39
Example: Drawing Alkane
Draw acceptable condensed structures andline drawingsassociated withthe following expanded structural formulas
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
10/39
Alkane Nomenclature
IUPACIUPAC (International Union of Pure and Applied Chemistry)(International Union of Pure and Applied Chemistry) Rules forRules forAlkaneAlkane NomenclatureNomenclature Findandnamethelongest continuous carbon chain. This is calledtheFindandnamethelongest continuous carbon chain. This is calledtheparentparent
chainchain. (Examples: methane, propane, etc.). (Examples: methane, propane, etc.)
Number the chain consecutively, starting attheendnearestanattached groupNumber the chain consecutively, starting attheendnearestanattached group
((substituentsubstituent).). Identify andname groups attachedto this chain. (Examples: methylIdentify andname groups attachedto this chain. (Examples: methyl--,, bromobromo--,,
etc.)etc.)
Designatethelocation of each substituent group withthenumber of the carbonDesignatethelocation of each substituent group withthenumber of the carbonparent chain on whichthe group is attached.parent chain on whichthe group is attached. PlaceadashPlaceadashbetweennumbersbetweennumbersandletters. (Example: 3andletters. (Example: 3--chloropentane)chloropentane)
Assemblethename, listing groups inalphabetical order.Assemblethename, listing groups inalphabetical order.
TheprefixesTheprefixes didi, tri, tetraetc., usedto designate several groups of the, tri, tetraetc., usedto designate several groups of thesamekind, arenot considered whenalphabetizing.samekind, arenot considered whenalphabetizing. Placea commaPlacea commabetweenmultiplenumbers. (Example: 2,3betweenmultiplenumbers. (Example: 2,3--dichloropropane)dichloropropane)
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
11/39
Step 1: Findtheparent chain.Findtheparent chain.
Where is theWhere is thelongest continuous chain oflongest continuous chain of
carbonscarbons ??
SubstituentsSubstituents - ParentParent
The Parent tells us how many carbon atomscan be found in the longest chain.The substituents indicate any groups that are
attached to the longest carbon chain.
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
12/39
Prefixes for # of CarbonsPrefixes for # of Carbons
11 MethMeth 66 HexHex
22 EthEth 77 HeptHept
33 PropProp 88 OctOct
44 ButBut 99 NonNon
55 PentPent 1010 DecDec
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
13/39
EndingEnding
AlkAlkaneaness (all C(all C--C single bondedparent chain)end inC single bondedparent chain)end inaneane
MethMethaneane CHCH44
EthEthaneane CC22HH66 PropPropaneane CC33HH88
Attached carbon groups (Attached carbon groups (substituentssubstituents)end in)end inylyl
MethMethylyl CHCH33 --
EthEthylyl CHCH33CHCH22--
PropPropylyl CHCH33CHCH22CHCH22
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
14/39
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
15/39
Step 2: Number theparent chain.Number theparent chain.
Number theparent chain so thattheattached
groups are onthelowestnumbers (
5 4 3 2 1
1 2 3 4 5
Methyl is on carbon #2 of theparent chain
Methyl is on carbon #4 of theparent chain
GREEN is the rightGREEN is the rightway for this one!way for this one!
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
16/39
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
17/39
Step 3: Nametheattached groups.Nametheattached groups.
Carbon (alkCarbon (alkylyl) groups) groups
MethMethylyl CHCH33 --
EthEthylyl CHCH33CHCH22--
PropPropylyl CHCH33CHCH22CHCH22 HalogensHalogens
FluoroFluoro (F(F--))
ChloroChloro ((ClCl--))
BromoBromo (Br(Br--))
IodoIodo (I(I--))
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
18/39
Step 4: Designate wherethe group isDesignate wherethe group is
attachedto theparent chain.attachedto theparent chain.
Usethenumbers of theparent chain from step 2 to
designatethelocation of theattached groups to the
parent chain.
1 2 3 4 5
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
19/39
Step5: Alphabetizethe groups,Alphabetizethe groups,
combinelike groups, andassemble.combinelike groups, andassemble.
Useanumericalprefix to indicate whenmorethan one of a same substituentexists inthemolecule)
Prefixes arenot considered whenalphabetizingarenot considered whenalphabetizing(Example: dimethyl =m for alphabetizing)
Parent chain goeschain goes LAST: The substituents arelistedalphabetically before theparent
Comma: numeral,numeralComma: numeral,numeral
Dash: numeralDash: numeral--letter orletter or
letterletter--numeralnumeral
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
20/39
Numerical Prefixes for NamingNumerical Prefixes for Naming
Identical GroupsIdentical Groups
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
21/39
Example: IUPAC Nomenclature
Provideacceptable IUPAC names for the following molecules
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
22/39
Givethenames of the following compounds using IUPACnomenclature
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
23/39
Draw Some Simple Alkanes:
22--methylpentanemethylpentane
33--ethylhexaneethylhexane
2,32,3--dimethylbutanedimethylbutane
Draw condensed structural formulas or linedrawings for each of the following compounds
3-ethylpentane
2,2-dimethylbutane
3-ethyl-2-methylhexane
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
24/39
Common Name
Thenumber of carbons inthealkane determines thename allalkanes with four carbons are butanes, those with five
carbons arepentanes, etc.
iso- indicates the chainterminates in-CH(CH3)2 , neo- that itterminates in-C(CH3)3
CH3 CH2 CH2 CH2 CH3
CH 3 CHCH3
CH 3
CH3 CH2 CHCH3
CH3
CH3CH
2CH 2CH 3
CH3CCH3
CH3
CH3
Pe n tan e Is op e n tan e
I s o buta neButane
N e o p e n t a n e
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
25/39
Classification of C & H
Primary (1Primary (1) C:) C: a carbon bondedto one other carbon 1 H: ahydrogen bondedto a 1 carbon
Secondary (2Secondary (2) C:) C: a carbon bondedto two other carbons 2 H: ahydrogen bondedto a 2 carbon
Tertiary (3Tertiary (3) C:) C: a carbon bondedto three other carbons 3 H: ahydrogen bondedto a 3 carbon
Quaternary (4Quaternary (4) C) C: a carbon bondedto four other carbons
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
26/39
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
27/39
Example:
Designateeach carbon of these compounds as
primary, secondary, tertiary, or quaternary:
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
28/39
Physical Properties of Alkanes
Nonpolar
Insoluble in water.
Lower density than water.
Low boiling andmelting points. Gases with 1-4 carbonatoms
methane, propane, butane
Liquids with5-17 carbonatoms
kerosene, diesel, and jet fuels:
Solids with 18 or more carbonatoms
wax, paraffin, Vaseline
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
29/39
Chemical reactions of Alkanes
Combustion:Combustion:
Alkanes react with oxygen.
CO2, H2O, andenergy areproduced.
Alkane + O2 CO2 + H2O +
heat
CH4 + 2O2 CO2 + 2H2O +
energy
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
30/39
Halogenation:
Alkanes react with Halogens.
CH4 + Cl2 CH3Cl + CH2Cl2 CHCl3 CCl4+ +
heat or light
=>
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
31/39
Properties Of Alkane
Alkane Formula
Boiling point
[C]
Melting point
[C]
Density [gcm3]
(at 20C)
Methane CH4 -162 -183 gas
Ethane C2H6 -89 -182 gas
Propane C3H8 -42 -188 gas
Butane C4H10 0 -138 gas
Pentane C5H12 36 -130 0.626(liquid)
Hexane C6H14 69 -95 0.659(liquid)
Heptane C7H16 98 -91 0.684(liquid)
Octane C8H18 126 -57 0.703(liquid)
Nonane C9H20 151 -54 0.718(liquid)
Decane C10H22 174 -30 0.730(liquid)
Undecane C11H24 196 -26 0.740(liquid)
Dodecane C12H26 216 -10 0.749(liquid)
Icosane C20H42 343 37 solid
Triacontane C30H62 450 66 solid
Tetracontane C40H82 525 82 solid
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
32/39
Source of Alkanes
Natural gas 90 to 95percentmethane
5to 10 percentethane, and
amixture of other low-boiling alkanes, chiefly propane, butane,
and 2-methylpropane. Petroleum
A thickliquidmixture of thousands of compounds, most of themhydrocarbons formed fromthedecomposition of marineplants andanimals.
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
33/39
Cycloalkanes
General formulaCCnnHH2n2n five- and six-membered rings arethemost common
Structureandnomenclature
to name, prefix thename of the corresponding open-chainalkane withcyclocyclo--,, andnameeach substituent onthe ring
if only one substituent, no needto give itanumber
if two substituents, number fromthe substituent of loweralphabetical order
if three or more substituents, number to givethemthelowestset of numbers andthenlist substituents inalphabeticalorder
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
34/39
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
35/39
THANK YOU....THANK YOU....
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
36/39
HOME WORKHOME WORK
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
37/39
1
Provide IUPAC names for thesealkanes:
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
38/39
2
Draw condensed structural formulas or line
drawings for each of the following compounds:
3-ethylpentane
2,2-dimethylbutane
3-ethyl-2-methylhexane
4-isopropyloctane
6-sec-butyl-7-ethyl-2,2,5,8-tetramethylnonane
-
8/7/2019 ORGANIC CHEMISTRY-ppt03
39/39
3
The following names have beenassigned incorrectly.
Draw the structure corresponding to thename, and
assignthe correct IUPAC name.
3-sec-butylpentane
2-ethyl-2,6-dimethylhexane