Finding major product after dehydration here,should I prefer hydride shift or a product with more $\alpha$ hydrogens?
my doubt is...as hydride shift is easier than methyl shift,the answer should be $a$ or $c$.if methyl shift takes place the alkene formed has more $\alpha$ hydrogens than $a$ and $c$.what should I prefer? The question is to find major product.also,irrespective of the answer I would like to know which is more stable $a$ or $c$?
Compound $a$ is stabler than compound $c$ because the alkene in $a$ has $7$ hyperconjugative structures due to $7 \alpha$-Hydrogen, whereas $c$ has only $5$ hyperconjugative structures.
Hyperconjugation or Nathan-Baker Effect is a stabilizing phenomenon due to resonance-like charge delocalisation. Also, the reason why here hydride shift takes place is because it leads to a stabler carbocation.
Hence the product should be $a$.