Question

Which of the following correctly reflects relative stabilities of carbocations? 3 degree allylic > 2 degree > 1 degree benzylic methyl > 2 degree benzylic > 3 degree 3 degree benzylic > vinyl >1 degree 2 degree allylic > 2 degree > vinyl 1 degree benzylic > 3 degree > 3 degree allylic Dehydrohalogenation of 2-bromobutane in the presence of a strong base proceeds via which of the following mechanistic pathways? S_N1 S_N2 E1 E2 none of the above Which of the following is least likely to be found in the product mixture which results when 2-iodopentane reacts with sodium ethoxide in ethanol? 1-ethoxypentane 2-ethoxypentane (Z)-2-pentene (E)-2-pentene 1 -pentene What is the major product which results when (2R, 3S)-2-chloro-3-phenylbutane is treated with sodium methoxide in methanol? (E)-2-phenyl-2-butene (Z)-2-phenyl-2-butene (S)-3-phenyl-1 -butene (R)-3-phenyl-1-butene (R)-2-methoxy-2-phenylbutane Why is the alkyl halide below not capable of undergoing an E2 reaction upon treatment with sodium ethoxide? Br^- is too poor a leaving group The substrate is too hindered Too much angle strain would be present m the alkene product Sodium ethoxide is a poor base to use in E2 reactions The C-H and C-Br bonds which need to break cannot achieve an anti-periplanar orientation.

Answer 1

12 D

vinyl is least

13 D correct answer

14 A

1-ethoxy pentane is possible rearranging 2º to 1º carbo cation rearrangement which is not possible

15 B or A

if it fillowes E2 mechanism B is answer

if it following E1 A is answer

16 E

in E2 mechanism leaving group and H must be antiperi planar which is not possible with this conformation