$1$

Mutah University

Chemistry Department

Organic Chem. I $(231)$

Fall Semester $2016/2017$

Final Exam

Name.............

$1-$ If a solutior cet answer for the following:

$15$ in $20cm$ of a compound of a solution$)$ has a measured rotation of $+$

A$)+50$

B$)+20$

C$)+15$

D$)+7\mathrm{.}50$

E$)+25$

$2-$ Which statement is not true for a meso compound?.

A$)$ The stereocenters must have identical configurations $($e$.$g R$,$R or S$,$S$)$

B$)$ At least there is one plane of symmetry

C$)$ The molecule is identical to its mirror image

D$)$ More than one chiral centers must be present

E$)$ The specific rotation equal zero

$3-$ Which of the following may be separated by ordinary physical methods?

A$)($R$)-3-$bromo$-1-$butene and $(5)-3-$bromo$-1-$butene

B$)(2R,35)-1,2-$dibromobutane and $(2S,3R)-1,2-$dibromobutane

C$)(R)-2-$bromobutane and $(S)-2-$bromobutane

D$)$ cis$-2-$bromo$-2-$butene and trans$-2-$bromo$-2-$butene

$4.$ Which of the following compounds is a meso compound?

A$)(2R,3R)-$dibromobutane

C$)(2R,3S)-$dibromobutane

B$)(2R,3S)-3-$bromo$-2-$butanol

D$)(2R,3R)-3-$bromo$-2-$butanol

$5-$ If $[a{]}_{25\%D}$ of pure $(S)-(+)-2-$butanol, $=+13\mathrm{.}52,$ and for pure $(R)-(-)-2-$butanol $=-13\mathrm{.}52.$

What is the percent composition of a mixture with a specific rotation, $[a{]}_{250}=+6\mathrm{.}76?$

A$)75\%(R)25\%(S)$

B$)67\%(R)33\%(S)$

D$)25\%(R)75\%(S)$

E$)$ It is hard to judge. More $,$ C$)50\%($R$)50\%($S$)$

$6-$ Which of the following is an $S_{N1}$ reaction?

A$)$

C$)$

D$)NaOH{H}_{3}O$ an

$7-$ Rank the following in order of decreasing reactivity with methanol $($highest to lowest$).$