Reactions with Strong Bases

Triphenylphosphine reacts with alkyl halides to form alkyltriphenylphosphonium salts. Upon reaction with strong bases, the salts release a proton to form an ylide (alkylidenetriphenylphosphorane), which is capable of reacting with aldehydes or ketones providing an unambiguous route to olefins. Since there are virtually no... 

An unexpected, one-step synthesis of a-chloro-P-lactones in 40-83% yield resulted when phenyl esters of a-chlorocarboxylic acids were treated under the conditions of the Darzens reaction with strong base in the presence of ketones or aldehydes <95AG(E)2028>. Previously, phenyl esters do not appear to have been used in this reaction. 

The whole range of carboxylic acids and alcohols can be reacted to form esters. They are found in a large number of natural and synthetic scents and perfumes because of their pleasant odor. Many are used as solvents for paints and resins. Esters are converted back into the original acids and alcohols hy reaction with strong bases in water in a process called saponification (soap formation). 

Adding H30+(aq) represents reaction with strong acid adding OH (aq) represents reaction with strong base. 

A different method of reduction involves the reaction with strong base, such as OH- and OR-. In this case, the primary reaction is nucleophilic attack on a carbon atom of a terminal carbonyl group as shown by the formation of a carboalkoxy group on reaction with alkoxide ... 

Metallation of alkynylcyclopropanes at the acetylenic end is accomplished either by deprotonation or via metal-halide exchange reaction with strong bases. Metallation of ethynylcyclopropane may be affected by KOH in DMF, ethereal EtMgBr or preferably BuLi in THF (equation 151)231. All three metal acetyl ides react with methyl ketones to give the corresponding alcohols. However, the instability of cyclopropyl ketones towards bases, especially at the reaction conditions required by KOH (20 °C, 6h), and the sensitivity of cyclopropenyl double bonds in cyclopropenyl ketone derivatives towards addition reactions of alkylmagnesium compounds, make the alkyllithium (-78 °C, instant reaction) superior to the other reagents. 

See also page 1717, Section 1 and page 1724, Section 2, for reactions with strong bases followed by protonation. 

The hydrogens on the methylene unit located between the two carbonyl functional groups are acidic due to the electron withdrawing effects of the carbonyl groups. Either or both of these hydrogens can be removed by reaction with strong bases. 

Reaction with strong bases by deprotonation at a C-hydrogen occurs in pyridine much more readily than in benzene. The intrinsic reactivity order is > > rather than, > because of lone pairlone pair repulsion in the -deprotonated species however, the use of special bases or the presence of tir/Zw-dirccting substituents can alter this order (cf. discussion in Section 3.2.1.8). 

The exceptional role of alcohols as solvents may arise from the fact that they are not only bases but simultaneously are acids. Therefore, unlike the reaction with strong bases, free acids are formed instead of carboxylate anions. 

An interesting property of mer-l VMe ) C and mer-Ir(PMe2Ph)3Cl3 is their reactions with strong bases such... 

Arynes are generated from aryl halides by reaction with strong bases. The final outcome of the reaction is substitution of the halide. 

The ketene 0,0-acetals 83 were prepared from the corresponding bromo derivatives by reaction with strong base A diastereoselective synthesis of the trans- and cis 84 was carried out. Condensation of substituted aminothiophenols and 2-arylidene-l-tetralone afforded 1,4-thiazepines 85. Condensation of o-phenylenediamines with P-ketoesters or 1,1,1-trifluoromethyl-3-(isobutoxymethylene)-2-propanones gave 84. ... 

Ring-opening of epoxides by P-elimination, on reaction with strong bases, such as lithium amides, or combinations of trimethylsilyl triflate with diazabicycloundecane, ° is a useful synthetic method to prepare allylic alcohols, particularly as it can be carried out enantioselectively. ... 

The metallation of a methyl group of PMe2R coordinated to a metal, leading to three-membered ring, occurs by the reaction with strong bases such as lithium diisopropylamine ... 

AMINOBENZENESULFONIC ACID or p-AMINOBENZENESULFONIC ACID (121-57-3) CsH NOjS HjO Decomposes on contact with strong acids, forming sulfur trioxide. The aqueous solution is acidic reaction with strong bases. Incompatible with alkylene oxides, aliphatic amines, alkanolamines, amides, ammonia, epichlorohydrin, organic anhydrides, isocyanates, oxidizers, vinyl acetate. On small fires, use dry chemical powder (such as Purple-K-Powder), Halon , water spray, or CO2 extinguishers. 

CjHyNOjS HjO Decomposes on contact with strong acids, forming sulfur trioxide. The aqueous solution is acidic reaction with strong bases. Incompatible with alkylene oxides, aliphatic amines, aUcanolamines, amides, ammonia, epichlorohydrin, organic anhydrides, isocyanates. 

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