CHEM 140A Chapter Notes - Chapter 7: Rate-Determining Step, Protic Solvent, Solvolysis

• School: UCSD
• Department: Chemistry and Biochemistry
• Course: CHEM 140A
• Professor: Joseph M Oconnor

Document Summary

Ochem textbook notes chapter 7: further reactions of haloalkanes. Rate of sn2 reaction diminishes when reacting center changes from primary to secondary to tertiary, but only in the case of bimolecular substitutions. Secondary and tertiary halides undergo substitution by another mechanism: solvolysis: substrate undergoes substitution by solvent molecules. Can use alcohol as a solvent: hydrolysis: solvolysis when the solvent is water relati(cid:448)ely slo(cid:449)er for se(cid:272)o(cid:374)dary stru(cid:272)tures, a(cid:374)d does(cid:374)"t o(cid:272)(cid:272)ur for pri(cid:373)ary ones, mechanism of solvolysis must be different from bimolecular substitution. Difference between bimolecular substitution and solvolysis: bimolecular substitution: sn2. Generates products stereospecifically with inversion of configuration fastest with halomethanes and successively slower with primary and secondary halides takes place only extremely slowly with tertiary substrates, if at all: solvolyses first order rate law. Characterized by the opposite order of reactivity solvolysis follows first order kinetics: more than one step in the reaction, the observed rate is that of the slowest step in the sequence: rate-determining step.