IIT-JEE 2010 · Paper 2 · Chemistry Q13

← IIT-JEE 2010 · Paper 2

ChemistrySingle correct+3 / -1Question 13 of 57

Passage

Paragraph for Questions 12 to 14

Two aliphatic aldehydes P and Q react in the presence of aqueous $\ce{K2CO3}$ to give compound R, which upon treatment with HCN provides compound S. On acidification and heating, S gives the product shown below:

3-Hydroxy-4,4-dimethyldihydrofuran-2(3H)-one (pantolactone): a five-membered lactone with a gem-dimethyl carbon next to the CH(OH) carbon α to C=O.

The compound R is

3-Hydroxy-2,2-dimethylpropanal: HOCH₂-C(CH₃)₂-CHO.

3-Hydroxy-2,2-dimethylbutanal: CH₃-CH(OH)-C(CH₃)₂-CHO.

2-(Hydroxymethyl)-3-methylbutanal: (CH₃)₂CH-CH(CH₂OH)-CHO.

2-(1-Hydroxyethyl)-3-methylbutanal: (CH₃)₂CH-CH(CHO)-CH(OH)CH₃.

Answer and worked solution

Official answer: A

R is the crossed aldol product, 3-hydroxy-2,2-dimethylpropanal, $\ce{HOCH2-C(CH3)2-CHO}$ . It has no α-H, so it does not react further under these conditions.

(A)

Topics:Aldol and related condensations

← Previous question Next question →

IIT-JEE 2010 · Paper 2, Chemistry question 13