Buna-S is made by 1,4-addition of buta-1,3-diene together with styrene, C6H5-CH=CH2. How many non-aromatic C=C bonds are there in a segment of the copolymer made of one butadiene unit and one styrene unit?

JEE Main levelSingle correct optionDifficulty 2 of 3pl084

Buna-S is made by 1,4-addition of buta-1,3-diene together with styrene, $C X_{6} H X_{5} - CH = CH X_{2}$ . How many non-aromatic $C = C$ bonds are there in a segment of the copolymer made of one butadiene unit and one styrene unit?

On 1,4-addition the diene unit becomes

- CH X_{2} - CH = CH - CH X_{2} X^{-}

, which keeps one

C = C

. Styrene polymerises through its vinyl group, which is used up, and the benzene ring is aromatic. Total = 1.