14.6 Synthesis of Alcohols Using Grignard Reagents ChaLi+ CHa LiNH, Methyllithium Ammonia Methane Lithium amide (stronger base)(stronger acid (weaker acid:(weake Kn=10-3 Ka≈10 60 H2CH2MgBr+HC≡CH CH3 CH3 Ethylmagnesiu Acetylene Ethane Ethynylmagnesium bromide (stronger bas =( (weaker base PROBLEM 14.4 Butyllithium is commercially available and is frequently used by organic chemists as a strong base. Show how you could use butyllithium to pre pare solutions containing (a)Lithium diethylamide (CHa CH2)2NLi b) Lithium 1-hexanolate Cha(cH )4 CH oli (c) Lithium benzenethiolate, CsHsSLi SAMPLE SoLUTION When butyllithium is used as a base, it abstracts a proton, in this case a proton attached to nitrogen The source of lithium diethylamide must be diethylamine (CH3 CH2)2NH+ CH3 CH2 CH,Li ->(CH3 CH2) NLi CH3CH2 CH2 CH3 diethylamide (stronger acid (stronger base) (weaker base) (weaker acid) Although diethylamine is not specifically listed in Table 14.2, its strength as an acid (Ka ss 10)is, as might be expected, similar to that of ammonia It is sometimes necessary in a synthesis to reduce an alkyl halide to a hydrocar- bon. In such cases converting the halide to a grignard reagent and then adding water or an alcohol as a proton source is a satisfactory procedure. Adding DO to a grignard reagent is a commonly used method for introducing deuterium into a molecule at a spe- Deuterium is the mass 2 iso- cific location pe of hydrogen. Deute. CH3 CH=CHBr CHaCH=CHMgBr CHCHECHD times called"heavy water. Propenylmagnesium bromide I-Deuteriopropene(70%) 14.6 SYNTHESIS OF ALCOHOLS USING GRIGNARD REAGENTS The main synthetic application of Grignard reagents is their reaction with certain car bonyl-containing compounds to produce alcohols. Carbon-carbon bond formation is rapid and exothermic when a grignard reagent reacts with an aldehyde or ketone normally COMoX written as rMgX R—MgX A carbonyl group is quite polar, and its carbon atom is electrophilic. Grignard reagents are nucleophilic and add to carbonyl groups, forming a new carbon-carbon bond. This Back Forward Main MenuToc Study Guide ToC Student o MHHE WebsitePROBLEM 14.4 Butyllithium is commercially available and is frequently used by organic chemists as a strong base. Show how you could use butyllithium to pre￾pare solutions containing (a) Lithium diethylamide, (CH3CH2)2NLi (b) Lithium 1-hexanolate, CH3(CH2)4CH2OLi (c) Lithium benzenethiolate, C6H5SLi SAMPLE SOLUTION When butyllithium is used as a base, it abstracts a proton, in this case a proton attached to nitrogen. The source of lithium diethylamide must be diethylamine. Although diethylamine is not specifically listed in Table 14.2, its strength as an acid (Ka 1036) is, as might be expected, similar to that of ammonia. It is sometimes necessary in a synthesis to reduce an alkyl halide to a hydrocar￾bon. In such cases converting the halide to a Grignard reagent and then adding water or an alcohol as a proton source is a satisfactory procedure. Adding D2O to a Grignard reagent is a commonly used method for introducing deuterium into a molecule at a spe￾cific location. 14.6 SYNTHESIS OF ALCOHOLS USING GRIGNARD REAGENTS The main synthetic application of Grignard reagents is their reaction with certain car￾bonyl-containing compounds to produce alcohols. Carbon–carbon bond formation is rapid and exothermic when a Grignard reagent reacts with an aldehyde or ketone. A carbonyl group is quite polar, and its carbon atom is electrophilic. Grignard reagents are nucleophilic and add to carbonyl groups, forming a new carbon–carbon bond. This normally written as COMgX R C R MgX O R MgX C O     Mg THF D2O 1-Bromopropene CH3CH CHBr Propenylmagnesium bromide CH3CH CHMgBr 1-Deuteriopropene (70%) CH3CH CHD (CH3CH2)2NH Diethylamine (stronger acid) CH3CH2CH2CH2Li Butyllithium (stronger base) (CH3CH2)2NLi Lithium diethylamide (weaker base) CH3CH2CH2CH3 Butane (weaker acid) CH3Li Methyllithium (stronger base) NH3 Ammonia (stronger acid: Ka  1036) CH4 Methane (weaker acid: Ka 1060) LiNH2 Lithium amide (weaker base) CH3CH2MgBr Ethylmagnesium bromide (stronger base) HCPCH Acetylene (stronger acid: Ka 1026) CH3CH3 Ethane (weaker acid: Ka 1062) HCPCMgBr Ethynylmagnesium bromide (weaker base) 14.6 Synthesis of Alcohols Using Grignard Reagents 553 Deuterium is the mass 2 iso￾tope of hydrogen. Deute￾rium oxide (D2O) is some￾times called “heavy water.” Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website