Chemistry Test Organic Chemistry 3

Question 1

Which reaction mechanism involves formation of a carbocation intermediate followed by attack of a nucleophile?

Accepted Answer

SN1

Answer

SN1 is a two-step process: ionization forms a carbocation intermediate, then the nucleophile attacks.

Question 2

In Markovnikov addition of HBr to propene, which carbon receives the bromine?

Accepted Answer

C-2 (internal carbon)

Answer

Markovnikov's rule states that H adds to the less substituted carbon and Br adds to the more substituted (C-2) carbon.

Question 3

Which functional group is characterized by a carbonyl carbon bonded to an —OH group?

Accepted Answer

Carboxylic acid

Answer

A carboxylic acid has the structure R–C(=O)–OH, with both a carbonyl and a hydroxyl on the same carbon.

Question 4

What is the product of catalytic hydrogenation of an alkyne using a Lindlar catalyst?

Accepted Answer

Cis-alkene

Answer

Lindlar catalyst (Pd/CaCO₃ with quinoline) delivers H₂ to the same face (syn addition), producing the cis-alkene.

Question 5

A compound has a molecular formula of C₆H₁₂. How many degrees of unsaturation (index of hydrogen deficiency) does it have?

Accepted Answer

1

Answer

IHD = (2×6 + 2 − 12)/2 = (14−12)/2 = 1, indicating one ring or one double bond.

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