Question

Question1:

In acidic conditions epoxides can be protonated. Protonated epoxides can undergo ring opening in the presence of poor nucleophiles. In these reactions the nucleophile preferentially attacks the more substituted carbon atom of the epoxide, as shown in the example below. Explain why the nucleophile preferentially attacks the more substituted carbon atom of the epoxide in acidic conditions. OCH3 он CH3 H3C CH3 H3C minor product major product

Answer 1

now we can easily explain why nucleophile Ch3OH prefer to attack on more substituted carbon reason is clear that after forst protonation step epoxide ring can open up in 2 way both shown above by different colour arrow movements now due to opening in two ways 1&2 two carbocations are formed 1st one is more stable cause is 2° stablized by +I effect so this more stable carbocation is responsible for attacking of nucleophile at more substituted carbon.

epoxide ung his con epon in tuo CH3 Нас ιση 애 OH carbo caluon cHs -6-H CH3- O H OH CM3 CH3 CHs OCH3 OH C Ha он HC CMs ma) mui mos)

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