CHEM 24 Dr. Spence
1.
(s)r-\g,4./v= (R )CI
3-methylhexane
.-,K^LR)
2-methylhexane3-chloropentane
c \
qi" o
^
Draw the following compounds and indicate any stereocenters with a (*). For those that havechiral centers, draw each enantiomer and label the configuration at each stereocenter (R or S).
2-chloropentane
OH
)"-a'
(K)
For each pair of molecules below indicate whether they are identical to each other or if they are
enantiomirs of each other. For those that are identical, draw the enantiomer.
COrH OH
","$o" "T$"o,"i c) La)
! "le,ati culo,
,enc.nL= hu"(4,1, tt 1
NHr
"4;s,*Cs)
Ho*sH3?H
H-=oo
!"' ?"",cr-f cF3 F3cTcH3
H
";.4.",C S )
--tA/ .\r"/
) Determine (R) or (S) configurations at all chiral centers in the following molecules'
9"",no*
t r z \Lr\ /
ocH3
(s rCI
(s)ErtarharYq{b
Dr. Spence
Consider the molecule 1-bromo-3-chlorocyclohexane and answer the following questions: (a)how many chiral centers are present? (b) what is the maximum number of stereoisomerspossible? (c) draw all the possible stereoisomers and label them A, B, C etc. (draw them as ahexagon using wedge and dash to indicate stereochemistry). (d) define the configuration at allchiral centers and describe the relationship between all stereorsomers.
Z chr(c^\ ce"rttc), 2' . I mo x fhrrur:'1,,'rf(1
CilrottL,$"uf
f "'^tf "'trtlzoFf
fNE,D
O-(R)-hypothetical a
lcrl =-32.0 d'^7\ lc
(tr
Draw all possible stereoisomers of the following compound. To make it easier, use Fischer
Cr{1or{
flo
l{ r> ,TD,IcH
Cr{zorl CdzPrl{,n850enan f*n^t(\
Given the following information about a hypothetical molecule, calculate the Yo optical purity of
a sample containing a mixture of the two enantiomers with an optical rotation [a] of (a) +33 .9'
and @16) _�l4.Io. Foi each of these mixtures also provide the relative o/o of each enantiomer (%R
and %S).
| (+)-(S)-hypothetical
n.\ 'a [6x]:+37.6c
q#r*lvs = fia3'% e&,'l,to/" {qrvrttc ,
y- A'= &fi'75%
% 9 = c t ; ' l % S = 7 l , a 5 v b
% 4 , ' 4 , 3
CHE}i{24
= { (:
c lnY)
AJ--SC, l
:(fi)=
ciC
Itr,n Uv}itr
n "c-9 * o
?r.ol-<reoot6%
0 + 9frtQ9*tC*(7
C|"tlcil
C IO
CF\.pfl
CHEM 24 Dr. Spence
7. For each pair of molecules below indicate if they are identical, enantiomers or diastereomers.
(2R,3R,4R ,5R)-2,3,4,5-tetrachto.fii&?FofiW$,h,0*,r, )-2,3,4,S-tetrachlorohexane
evro.n\u'nrec>/\7cu.r ."\roHt t t l9ou ..*cH,
H. ,CH: HrC. .CHr\ - / \ _ . /
H : C H H H
l .
c/rc{ )lt(fbrv*6'
to[o"r\ r,al (*t2 )
crt"'"'t])4cu, Hrc*
/"\/"n t i l\-,.-
t u
1. OsOa2. NaHSO3
H Hl l
H3c-.|- Br Br--]- cHs
H3Cf Br Br--|- H
H CHst i r
drca) ftfrun^t(5
-+*o{e-,-&crlov
ff-ouI-\.J-- o.rl
1. OsOa2. NaHSO3
gnGfll"',)nEf >tr*t)'l chn6:{ I€qvc,l cn*1,*rn$
Jra2hrturrt()Vo7'v-t Ch,<al
***:, "rn'*nTb
Jiq>hrrtrnef>!7"th ch.(o'lun€r1.tal aftJbflt>
,J,olJ*'re,lrrcq5Urreq,tul a'rna{tfi
J oH BrzV /l\-.\,,'\ +
nC h'r&l
Draw all possible (stereoisomeric) products from each of the following reactions. Label theproducts A, B, C, etc and describe the relationship between the possible products. Indicatewhich molecules are chiral. Indicate if all products form in equal amounts or unequal amounts.If the product mixture is expected to be optically active check the box in front of the reaction.
/:d,, oill lI
_ - l l r l6 f l
r+
,I--{,,, od/ - [ , , , e i1
l1
CIl-{ wryR 9r-
tt.+;z:-( t t\-5--;
7
rt
tneS7; vlot Cht(a l
'Lt''*'r W'HBr
{nv,J
CHEM 24 Dr. Spence
9. While considering the cyclohexane ring as a planar hexagon, draw an optically active version of1,2,3,4,5,6-hexachlorocyclohexane.
Cl r l t / /
, r , , , C i
CI$tt o*Lo h*ot c^
{la*rnt CIC 51nn'r'et*7il
C I
10. For the first compound in question 8, identifu all pro-chiral sp'carbons. Are you looking at theRe face or Si face? For the last compound in question 8, identify all pro-R positions.
/----t gro'-ch'c'""1 ((t fr*tt)
r \\- gro -ch,{a I (9, h"e)
c a nQt'' *t l t\ r ;
CH."'\t>ll l \
c>HfY'f,^u R 'l*- ftt R
11. Circle the chiral centers in the following compounds.
12. Label with a "*" all the chiral centers in the following molecules.
13. Identify the following pairs of compounds as enantiomers, diastereomers, or the same.
HO
OH
O
HO
O
OH
Cholesterol Prostaglandin E2
C
N
OCH3
O
H
H
OCH3
O
cocaine
NHCO2CH3
O
H
H3CSSS H OR
C C
C
calecheamicin
**
*
**
*
Br Br
Br Br
OHOH
OH
HO
diastereomers enantiomers
diastereomersenantiomers
14. Identify the following pairs of compounds as enantiomers, diastereomers, constitutional isomers, or the same. a. diastereomers
b. enantiomers
15. Identify the stereocenters in the following molecules and indicate whether they are R or S.
16. Using the tests for chirality we have learned, determine whether the following molecules are chiral. Determine the configuration (R or S) of any chiral centers in the molecules.
Br Br Br Br
OH
HO
HOH
H
ClHO OH
O
NH2
RS
S
not a stereocenter!
R S
S
OH
O
CH3 OHOHHO
CH3
NH2CH3 OH
Br
chiral
achiralno stereocenter
achiralmeso
achiralmeso
chiral chiral
R
S
R RS S
S
R
17. Circle those molecules below that are chiral.
18. Name the compound below. Be sure to include R,S designations.
S-3-methylhexane 19. Determine the relationship between the following pairs of molecules: enantiomers, diastereomers, identical, or structural (constitutional) isomers. a. structural isomers
b. diastereomers
c. identical -- no chiral center
Cl
Cl ClHO
Cl
Cl
OH
O CH3
CH3
CH3
Br Br
NH2
NH2
NH2
NH2
OH
HO