1559r.ah07.113-13110/22/0520:20Page116 116 chapter 7 FURTHER REACTIONS OF HALOALKANES:UNIMOLECULAR SUBSTTTUTION AND PATHWAYS OF ELIMINATION Substitution or elimination?Analysis: Factor Favors SUBSTRATE is primary:unhindered Substitution NUCLEOPHILE isNH2:strongly basic NUCLEOPHILE is-NHa:sterically unhindered Substitution Result:Substitution,to form CHaCHaCH2CHaNH2 Type of nuclophile Weakly basic Strongly basic ere c like (CHCO No reaction Sl and EI Solutions to Problems OCH2CF3 22.(a)(CHa)sCOCH:CH3 (b)(CHa)2CCH-CHa CHCH,OCH -OCH CH (e)(CHa)COD 0ac-0 23.(a)For the answer to this part we show each step on a separate line CH3 cH,-CBr一cH,-Ct+Br CHs116 • Chapter 7 FURTHER REACTIONS OF HALOALKANES: UNIMOLECULAR SUBSTITUTION AND PATHWAYS OF ELIMINATION Substitution or elimination? Analysis: Factor Favors SUBSTRATE is primary: unhindered Substitution NUCLEOPHILE is NH2: strongly basic Elimination NUCLEOPHILE is NH2: sterically unhindered Substitution Result: Substitution, to form CH3CH2CH2CH2NH2. The text summarizes the preferences for E1, E2, SN1, and SN2 reactions for 1, 2, and 3 haloalkanes, as a function of reaction conditions, in quite a bit of detail. The chart that follows repeats the same material, again somewhat oversimplified for clarity (solvent effects are not included, for instance). SUMMARY CHART Major reactions of haloalkanes with nucleophiles Type of nucleophile Weakly basic Strongly basic Strongly basic Poor good unhindered hindered Type of nucleophile nucleophile nucleophile nucleophile halide like H2O like I like CH3O like (CH3)3CO Methyl No reaction SN2 SN2 SN2 1 No reaction SN2 SN2 E2 2 Slow SN1 SN2 E2 E2 3 SN1 and E1 SN1 and E1 E2 E2 Solutions to Problems OCH2CF3 A 22. (a) (CH3)3COCH2CH3 (b) (CH3)2CCH2CH3 (c) (d) (e) (CH3)3COD (f ) 23. (a) For the answer to this part we show each step on a separate line. Br C Br CH3 CH3 CH3 C CH3 CH3 CH3 (CH3)3C H O C CH3 CH3 OCH O CH3CH2 OCH3 1559T_ch07_113-131 10/22/05 20:20 Page 116