Discussion Forum



1)

P and Q are isomers of dicarboxylic acid C4H4O4. Both decolourize Br2/ H2O . On heating, P  forms the cyclic anhydride

Upon  treatment with dilute alkaline  KMnO4 .p as well as Q could produce  one or more than one form S, T and U

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  Compounds formed from P and Q are, repectively 


A) Optically active S and optically active pair (T,U)

B) Optically inactive S and optically inactive pair (T,U)

C) Optically active pair (T,U) and optically active (S)

D) Optically inactive pair (T,U) and optically inactive S

Answer:

Option B

Explanation:

Plan alkenes declourise Br2 water

 cis-isomer $\underrightarrow{ dil.KMnO_{4}}$  Meso isomers by syn addition

 trans-isomer  $\underrightarrow{ dil.KMnO_{4}}$ d(+) and l(-) isomers by syn addition

 thus, reacemic mixture

 Formation of anhydride from  dicarboxylic acid indicates cis-isomer

 P and Q are isomers of dicarboxylic acids

 P,Q   $\underrightarrow{ Br_{2} water}$  decolourised

 P and Q have (C=C) bond 

P  $\underrightarrow{\triangle}$ anhydride

 Thus , P is cis-isomer

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 T and U  (in 1:1 molar ratio)  form optically inactive (racemic mixture) due to external cancellation