Question 1

How many terminal alkynes have a molecular formula of $$\mathrm{C_5H_8}$$?

Accepted Answer

2

Question 2

What is the hybridization of the carbons numbered 1 and 2 in the following compound: $$\mathrm{CH_3C\equiv CCH_2CH_3}$$?

Accepted Answer

sp, sp

Question 3

The carbon-carbon triple bond of an alkyne is composed of:

Accepted Answer

one $$\sigma$$ bond and two $$\pi$$ bonds

Question 4

How many bonds in the following compound are formed by sp-sp overlap: $$\mathrm{CH_3C\equiv CCH_2CH_3}$$?

Accepted Answer

1

Question 5

Which of the following is the major product of hydroboration-oxidation of phenylacetylene ($$\mathrm{C_6H_5C\equiv CH}) as $$shown in the image: $$\mathrm{1.\ R_2BH\ 2.\ HO^-,\ H_2O_2,\ H_2O}$$?

Accepted Answer

IV. $$\mathrm{C_6H_5CH=CHOH}$$

Question 6

Keto-enol tautomers are:

Accepted Answer

constitutional isomers

Question 7

Which reagent is needed to convert 2-butyne to cis-2-butene?

Accepted Answer

$$\mathrm{H_2$/Lindlar's\ catalyst}$$

Question 8

In the hydroboration-oxidation reaction of a terminal alkyne, the product is:

Accepted Answer

an aldehyde

Question 9

Which alkyl halide reacts the fastest in an E1 reaction?

Accepted Answer

benzyl chloride (see image)

Question 10

Why does the alkyl halide shown below (see image of cyclohexane with axial Br and methyl groups) not undergo an E2 reaction with sodium ethoxide?

Accepted Answer

The C-H and C-Br bonds which need to break cannot both be in axial positions.

Question 11

What is the major product of the following reaction: $$\mathrm{(CH_3$)_2CHCH_2CHBr(CH_3$)_2}$$ with $$\mathrm{KOC(CH_3$)_3}$$?

Accepted Answer

2-isopropyl-1-pentene

Question 12

Which sequence of reagents should be used to convert 1-bromobutane to hexane?

Accepted Answer

1. NaC\equiv CH 2. $$H_2 ($$excess), Pd/C

Question 13

A mixture of 1-heptyne, 2-heptyne, and 3-heptyne was hydrogenated in the presence of Pd/C. If one assumes that the hydrogenation went to completion, how many seven-carbon hydrocarbons were produced?

Accepted Answer

1

Question 14

What are the products of the following reaction: $$\mathrm{CH_3OH + CH_3C\equiv C^-}$$?

Accepted Answer

$$\mathrm{CH_3C\equiv CH + CH_3O^-}$$

Question 15

Which of the following alkyl halides ionizes to form the most stable carbocation?

Accepted Answer

IV. $$\mathrm{benzyl chloride}$$

Question 16

Which of the following is the best method to convert 2-butene to 2-butyne?

Accepted Answer

$$Br_2$$/$$CCl_2$$; 2NaNH_2

Question 17

What is the major product of the following reaction: $$\mathrm{C_6H_5CH_2C(CH_3$)_2Br}$$ with $$\mathrm{KOH} ($$see image)?

Accepted Answer

IV. $$\mathrm{C_6H_5CH_2C(CH_3$)=CH_2$}$$

Organic Chemistry Exam Practice: Reactions, Mechanisms, and Concepts

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