OCHEM TEST 1 Review

The Markovnikov product resulting from an addition reaction to an unsymmetrical alkene is formed because:

the reaction proceeds via the more/most stable carbocation.

The decrease in entropy (the ΔS value is negative) is observed for alkene addition reactions because of:

two molecules reacting to form a single molecule

Which of the structures shown depicts the most stable carbocation intermediate formed in the hydrohalogenation reaction shown?

D

For the following reaction sequence provide the expected major organic product(s). Include all stereoisomers showing relevant stereochemistry

E

What are the major products of the following reaction including the stereochemistry?

E

What is(are) the expect major products(s) of the following reaction including stereochemistry?

E

What is(are) the expect major products(s) of the following reaction?

E

Which of the following correctly depicts the mechanistic first step in the addition of HBr to 2- methylpropene?

E

What is the expected major product(s) of HCl addition to the alkene below?

I and II

Which of the molecules below are enantiomers formed as products of the following reaction?

II and IV

Which reagent below would be used for the following conversion

Na, NH3(l)

Which of the bases below would result in the most complete deprotonation of the alkyne, shown in the reaction below?

NaH (sodium hydride)

Provide the expected organic product(s) of the reaction sequence shown.

b and c

Rank the following carbocations (a -c) in order of increasing stability (from least stable to most stable).

c < a < b

What would be the optimal conditions to effect the following synthesis

dilute aqueous H2SO4

Explain the following reaction mechanism

first, more stable secondary carbocation forms, then carbocation rearrangement happens before bromide attacks from both side (front and back)

In an addition reaction to an alkene, the π bond plays the role of:

nucleophile

The C≡C bond of an alkyne is composed of which bond types

one σ bond and two π bonds

Which of the following species is the most appropriate intermediate in the bromination of cyclohexene

D

How many of the following reagents cause ONLY anti-addition?

1

What are the products of the following reaction? (This question is a combination of hydrogenation of alkene and alkyne :)

A

What is the major products of the following reaction?

A

Which of the following compounds would react most rapidly with a dilute aqueous solution of H2SO4?

A

Identify which of the following compounds represent a pair of keto-enol tautomers:

All of them

The three compounds below can form a carbocation under aqueous acidic conditions. Which ones will form the same carbocation?

All three will form the same carbocation

The regioselectivity and stereospecificity in the hydroboration-oxidation of an alkene is best described as:

Anti-Markovnikov orientation with syn-addition

Of the alkenes shown, which would produce the product shown below, upon treatment with ozone, followed by zinc metal and water?

B

Predict the major products

B

What is the major product of the following reaction?

B

What is the major product of the following reaction? (Hint: Markovnikov's rule!)

B

Which of the alkenes shown below would produce a chirality center upon Markovnikov hydrohalogenation?

B

Which of the following cations is most likely to undergo rearrangement? (Hint: It should form more stable carbocation. (i.e. 1˚-->2˚ or 1˚-->3˚ or 2˚--> 3˚)

B

Consider a stepwise mechanism for the following reaction. What is (are) the intermediate(s) of the carbocation(s)? (Pick all possible carbocation(s) form during the reaction).

C

What is the expect major product of the following reaction sequence?

C

What is(are) the expect major products(s) of the following reaction sequence?

C

Which of the following compounds is (are) a tautomer(s) of compound X drawn below?

Compounds A and B are both tautomers of compound X.

Select the expected major product of the following reaction. If carbocation rearrangement is possible, consider it

D

The expected major product of the following reaction is

D

What are the products of the following reaction sequence including their stereochemistry?

D

What is(are) the product(s) of the following reaction including the stereochemistry?

D