Question

5. Predict the eliminations products A and B formed (E-1 mechanism) when 4,4-dimethylhexan- 3-ol is heated with concentrated phosphoric acid. Also, identify the rate determining step and the major product using Zaitsev's Rule? (Mechanism must be shown to receive full points). (20 pts) Он conc. H3PO4 Products A and B .CH3 Нас H3C CH3 E-l condition 4,4-dimethylhexan-3-ol

Answer 1

5. Ans :-

According to Zaitsev's rule more alkylated alkene (having more alpha hydrogen) would be the major products. In this reaction stable tertiary carbocation is formed which generate two alkenes out of which is more alkylated (B) (having 10 alpha hydrogens) will be the major product and which is less alkylated (A) (having 7 alpha hydrogen) will be minor.

5. Sol! → он CH3 conc. H3PO3 E-1 condition CH3 H₂ , + CH₃ Cita CH3 (A). Min 091 (7-H) СН3 Mecanism (B). Maior (10-WH OH CM3+ to o G Chia 03 > Ho Wee CHig Her er Secondary (2) Cowbocahon with 20- Hydrogens less stable. CH3 CH₂ H(a). CH₃ CH V Ho lib CHg 3 Tertiasty) Carbocation Mb CH Mogle stable -H+ 2 CH3 -47 X Myce UH+ C (a). CH3 2°canbocation with 50-H + less stable -H" CH CH₃ ,CH₃ 47 m CH3 нс 3 CH3 . B Major A Minoet 72-H MyC TOK-H Hz