The major product of the following reaction is :
`C_6H_5CH_2-overset(CH_3)overset(|)underset(Br)underset(|)(C)-CH_2-CH_3overset(C_2H_5ONa)underset(C_2H_5OH)rarr`

Options

A. `CH_3-overset(CH_3)overset(|)underset(H)underset(|)(C)-CH_2OCH_3`
B. `CH_3-underset(OCH_3)underset(|)(CH)-CH_2CH_3`
C. `CH_3-overset(CH_3)overset(|)(C)=CH_2`
D. `CH_3-overset(CH_3)overset(|)underset(OCH_3)underset(|)-CH_3`

Answer

D

Explanation

`H_3C-overset(CH_3)overset(|)underset(H)underset(|)(C)-CH_2-Br overset(CH_3O^(-))underset(CH_3OH)(rarr)A`
Alkyl halide is `1^@`
Keep in mind `1^@` halide give product by `S_N^2//E2` mechanism and `1^@` halide always gives substitution reaction except when strongly hindered base is used.
ex: With `CH_3-overset(CH_3)overset(|)underset(CH_3)underset(|)(C)-O^((-))` it gives mainly elimination. The reaction involves carbocation intermediate.
i.e. `CH_3-overset(CH_3)overset(|)underset("(primary carbocation)")underset(H)underset(|)(C)-overset(oplus)(CH_2)`
but as it is a primary carbocation it will rearrange to give a tertiary carbocation, which completes the reaction
`CH_3-overset(CH_3)overset(|)underset("tertiary carbocation")underset(CH_3)underset(|)(C^(oplus))`
Stability of carbocation : `3^@ gt 2^@ gt 1^@ gt overset(oplus)(CH_3)`
It is because the stability of a charged system is increased by dispersal of the charge. The more stable the carbocation, the faster it is formed. N.B. – Rearrangement can be done in two ways.