Question

3. for each of the following, choose the reaction that would proceed more rapidly and give an explanation for your choice: (a) iodomethane or bromomethane with aqueous KOH (b) iodomethane or iodoethane with aqueous KOH (c) methanol or bromomethane with Nal dissolved in acetone (d) 2-bromopropane or 1-bromopropane with Nal dissolved in acetone (e) 2-bromo-2-methylbutane or 2-bromo-3-methylbutane with ethanol (f) aqueous KBr or aqueous HBr with butanol (g) 2-chloro-3,3-dimethylbutane or 2-chloro-3-methylbutane with potassium tert- butoxide (h) 1:1 or 1:4 by volume H20 : ethanol with 2-chloro-2-methylpropane (1) H2O or HS with 1-bromopentane 0) NaCN in H.O or NaCN in (CH),S-O with methyl iodide

Answer 1

3. (a) Sodomethane with ay. KOH Between Todomethane and bromo methane the leaving ability of the halide I> Br. Thats why in this SN 2 reaction Todomethane with ag. KOH twill be is faster than Bromomethane. (6) Todomethane with ag. KOH SN 2 reaction proceed rapidly and in case of iodoethane with as Koh its slower. This is because of the sterie hinderance of alkyl halide. (e) Between methands and bromomatrane with Na I dissolve in acetone, bromomethane will gine rapidly reaction. Becane of the leaving group ability of Br.atan. The reaction will proceed SN2 fathway as the solvent is palan aprofic (d) Between 2-bromopropane and f-bromo propane with Na I dissolve in acetone, 1 bromopropane witha proceed SN2 reaction rapidly. Due to the order of reactivity of SN2 20 <10 -alby halide. HC HC-C-CH3 (2-bromo-2-methyl butane) Br 30 halide H3C- CH CH CH₂ (2-bromo-3-methyl butane) Hz Br 20- halide 2: bromo-2-methyl butane with ethand will react rapidly compare to 2-bromo-3 methys butane. Because in polar profie solvent snl reaction favours 3° 72°-halide. (4) Ag. HBr will proceed rapidly compare took By with butands becausse in the former case the proton canabind with butanol -OH group. and the removal of OH will be easier for HGHE-OH HBr > H+63 - H₂C-B Br H₂ C3-H₃C-Br

CH3 CH3 (9) HE-C-CH-CH3 . H3C-CH HC- CH3 with Ktober ceza i Between 2 chloro-33 dimethy I butane od 2-chloro 1-3-methy bertane the last one will proceed reaction rapidly. Because of the product stabilty of the last one through E2 pathway. MEHe=CH₂ Me C-CHR 1 H2O: Etoh Slow reaction. ce l or Rapid reaction 1:4 reactim H₂O: Etor In presence of polan protic solvent EroH. SN 1 reaction will happen. More potentie solvent stabilize the 3 cabocation. So the later case rear is rapid. e , thox Rapid 1 HE ACHEHEHEB H₂S slow H2O is good nucleophile than Has thats what with H2O the SN2 reaction will be fasten. (K) Me-I NOCN i Slower H2O Nach - DMSO Rapid SN 2 reaction favours in presence of polac aprotic solvent. So in presence of PMSO the SNL reaction will be rapid proceed rapidly