Question

When determining which mechanism (E1 or E2) occurs, the following process is helpful: 1) Determine the substitution (methyl, 1º, 2º, or 3“) of the alkyl halide 2) Determine the strength of the nucleophile Please fill out the following table, indicating the category of reaction (E1 or E2) that will occur in each set of alkyl halides and nucleophiles. If no reaction occurs, write 'NR: Alkyl Halide Strong Base Weak Base Methyl 1° 20 3° For each of the following reactions, determine which ELIMINATION mechanism (E1 or E2) will occur. Alkyl Halide Substitution: Methyl 1° 2° 3° Base Strength: Strong Weak Mechanism Type: E1 E2 Draw the mechanism that leads to ALL products for the reaction. Finally, underline the major product of the elimination reaction: H3C OH H2C H3C Br CH3

Answer 1

E and Ez mechanisms Let ws RI 1 observe the a weak base ROH Rz Co R2-C-X RI xo 1 (Hr CH R2 CHg R ki Rs Carbocation Reaction is favored by Carbocation Stability weak base is sufficient to polarise alkylbatice. a RI RI 1 RI 1 RE C-X R2-C -- X kat Тga Rog EL » R₃-CH=CCR CHOR Transition state Reaction Mate depends on both base and alkyl kalide strong bases Rreffered of methyl halide and Primary alkyl halicles, polarisation is difficult hence strong weak base CH3- In case base - X Εγ iR-X Ev Er In case of important go R-X and 3R-base plays the Role strong base weak base El 20 R-X E2 30 R-x Ez Ei

ÖH یہ و یه BY CH₂ are by Hypes Conjugation He weak base, hence E mechanism is favored. the possible Elimination product HS 7a- Hydrogen 3 c4-Hydrogen 94-Hydrogen are stabilising che Stabilizing the alkene by Hyper conjugaction H H H H H H H н Н CH3 CH₃ are stabilizing the alkene the alkene. more stable alkene