CHAPTER FIFTEEN Alcohols, Diols, and Thiols TABLE 15.1 Summary of Reactions Discussed in Earlier Chapters That Yield Alcohols( Continued) Reaction(section) and comments General equation and specific example Hydroboration-oxidation of alkenes (Section 6.11) The elements of water R2 C=CR2 →> RCHCR add to the double bond with regio- lectivity opposite to that of mar kovnikov' s rule. This is a very good Alkene Alcohol synthetic method; addition is syn, CH3(CH2)7 CH=CH2 CH3(CH2)7 CH2CH2OH 1-Decene 1-Decanol (93%) Hydrolysis of alkyl halides(Section 8.1) a reaction useful only with sub strates that do not undergo E2 elimi- Alkyl Hydroxide Alcoh nation readily. It is rarely used for e synthesis of alcohols, since alkyl CH CH alides are normally prepared from H3C H 2, 4, 6-Trimethylbe 2,4.6-T alcohol (78%) Reaction of Grignard reagents with aldehydes and ketones(Section 14.6) A method that allows for alcohol RMgX R'CR preparation with formation of new carbon-carbon bonds. Primary, sec- R ondary, and tertiary alcohols can all Grignard Aldehyde Alcohol be prepared gent or ketone H CH2OH Cyclopentylmagnesium Formaldehyde Cyclopentylmethanol Reaction of organolithium reagents with aldehydes and ketones (Section 14.7)Organolithium reagents react RLi + RCR RCOH with aldehydes and ketones in a manner similar to that of Grignard reagents to form alcohols. Aldehyde Alcohol or ketone CHa CH2 CH2 CH2Li CH3 CH2 CH2CI Butyllithium Acetophenone 2-Phenyl-2-hexanol(67%) Back Forward Main MenuToc Study Guide ToC Student o MHHE WebsiteTABLE 15.1 Summary of Reactions Discussed in Earlier Chapters That Yield Alcohols (Continued) Reaction (section) and comments General equation and specific example Reaction of Grignard reagents with aldehydes and ketones (Section 14.6) A method that allows for alcohol preparation with formation of new carbon–carbon bonds. Primary, sec￾ondary, and tertiary alcohols can all be prepared. Aldehyde or ketone RCR O X Grignard reagent RMgX Alcohol RCOH W W R R 1. diethyl ether 2. H3O 1. diethyl ether 2. H3O H MgBr Cyclopentylmagnesium bromide H CH2OH Cyclopentylmethanol (62–64%) HCH O X Formaldehyde Reaction of organolithium reagents with aldehydes and ketones (Section 14.7) Organolithium reagents react with aldehydes and ketones in a manner similar to that of Grignard reagents to form alcohols. Aldehyde or ketone RCR O X Organolithium reagent RLi Alcohol RCOH W W R R 1. diethyl ether 2. H3O CH3CH2CH2CH2Li Butyllithium 2-Phenyl-2-hexanol (67%) CH3CH2CH2CH2±C±OH CH3 Acetophenone CCH3 O X 1. diethyl ether 2. H3O Hydrolysis of alkyl halides (Section 8.1) A reaction useful only with sub￾strates that do not undergo E2 elimi￾nation readily. It is rarely used for the synthesis of alcohols, since alkyl halides are normally prepared from alcohols. Alkyl halide RX Hydroxide ion HO Alcohol ROH Halide ion X H3C CH3 CH2Cl CH3 2,4,6-Trimethylbenzyl chloride H3C CH3 CH2OH CH3 2,4,6-Trimethylbenzyl alcohol (78%) H2O, Ca(OH)2 heat (Continued) Hydroboration-oxidation of alkenes (Section 6.11) The elements of water add to the double bond with regio￾selectivity opposite to that of Mar￾kovnikov’s rule. This is a very good synthetic method; addition is syn, and no rearrangements are observed. 1. B2H6 2. H2O2, HO Alkene R2CœCR2 Alcohol R2CHCR2 OH W 1. B2H6, diglyme 2. H2O2, HO 1-Decene CH3(CH2)7CHœCH2 1-Decanol (93%) CH3(CH2)7CH2CH2OH 582 CHAPTER FIFTEEN Alcohols, Diols, and Thiols Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website