2,2-Dimethylpropyl (neopentyl) tosylate, $(CH X_{3}) X_{3} C - CH X_{2} - OTs$ , is heated in absolute ethanol with no added base. Ignoring elimination products, the major substitution product is

A $(CH X_{3}) X_{2} CH - CH (OC X_{2} H X_{5}) - CH X_{3}$ (2-ethoxy-3-methylbutane)
B $(CH X_{3}) X_{3} C - CH X_{2} - OH$ (neopentyl alcohol)
C $(CH X_{3}) X_{3} C - CH X_{2} - OC X_{2} H X_{5}$ (neopentyl ethyl ether)
D $(CH X_{3}) X_{2} C (OC X_{2} H X_{5}) - CH X_{2} CH X_{3}$ (2-ethoxy-2-methylbutane)

Answer: D

Direct SN2 on neopentyl is practically blocked by the three beta methyl groups. Under solvolysis the ionisation is accompanied by migration of a methyl group (a 1,2-methyl shift), giving the tertiary cation

(CH X_{3}) X_{2} C X^{+} - CH X_{2} CH X_{3}

. Ethanol captures this cation to give 2-ethoxy-2-methylbutane after loss of a proton.

Practice Organic Reaction Mechanisms III: Nucleophilic Substitution More on SN1 vs SN2: substrate, nucleophile, solvent, leaving group

Previous questionNext question

2,2-Dimethylpropyl (neopentyl) tosylate, (CHX3​)X3​C−CHX2​−OTs, is heated in absolute ethanol with no added base. Ignoring elimination products, the major substitution product is

Answer: D

More questions on SN1 vs SN2: substrate, nucleophile, solvent, leaving group

2,2-Dimethylpropyl (neopentyl) tosylate, $(CH X_{3}) X_{3} C - CH X_{2} - OTs$ , is heated in absolute ethanol with no added base. Ignoring elimination products, the major substitution product is