Select all of the false statements regarding reactions of alkenes and alkynes. M

Question

Select all of the false statements regarding reactions of alkenes and alkynes. Multiple answers: You can select more than one option O A The addition of HBr to an alkene proceeds through a carbocation intermediate When H2 is added to an alkyne in the presence of Lindlar's catalyst (Pd/CaCO3) a trans a kene is formed The addition of Br2 to an alkene proceeds through a bromonium intermediate; produci ng an anti addition product O D In the presence of Pd; H2 adds anti to an alkene and an alkyne OE In the presence of Pd; H2 converts an alkyne into an alkane When either an alkene or an alkyne is treated with ozone cleavage of the double or tripl e bond always occurs O F

Explanation / Answer

A: True

In the first step of addition of HBr to alkene, proton from HBr added to double boned carbon alkene results formation carbon cation intermediate. in the second step, bromide nucleophile added to the carbon cation.

B. False

Hydrogenation of alkyne in the presence of Lindlar's catalyst gives cis alkene.

C. True

The addition of bromine to alkene results bromonium ion intermediate and once the bromonium ion is formed, the bridged bromine atom blocks the side of the ion from further attack. So, the anti product is the result.

D: False

Hydrogenation of alkene or alkyne is syn addition.

E: True

Hydrogenation of alkyne gives alkene and further addition gives alkane.

F: True.

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