Materials sodium tert-butoxide

Representative Procedure for the Use of Benzophenone Imine as an Ammonia Equivalent (Excerpted with permission from [108]. 1996 Pergamon Press) A Schlenk tube was charged with sodium tert-butoxide (1.4 mmol), Pd2(dba)3 (0.00125 mmol), and BINAP (0.00375 mmol). The Schlenk tube was fitted with a septum and attached to a Schlenk line. After the air atmosphere was replaced with argon, toluene (4 ml), 4-tert-butylbromobenzene (1.0 mmol), and benzophenone imine (1.2 mmol) were added by syringe. After the septum was replaced with a teflon valve, the reaction was sealed and heated to 80 °C with stirring until starting material was consumed as judged by GC analysis. The reaction mixture was cooled to room temperature, diluted with ether (40 ml), filtered, and concentrated. The crude reaction mixture was then recrystallized from MeOH to furnish the desired product in 90% yield. 

Sodium tert-butoxide is purchased from Aldrich Chemical Company, Inc., and used without further purification. The bulk of this material is stored under nitrogen in a Vacuum Atmospheres Glovebox. Small portions (10-15 g) were removed from the glovebox in glass vials and weighed in the air. The checkers stored sodium tert-butoxide, purchased in 5-g bottles, in a desiccator and weighed it out in air. 

Another method has been described for the synthesis of halide-free ILs which uses an imidazolylidene carbene as an intermediate. The starting material is an imidazolium halide which is treated with sodium tert-butoxide to form an imidazolylidene carbene. The latter is distilled in a Kugelrohr apparatus, then reacted with a Br0nsted acid. In this way, it is possible to obtain an IL free from halide contamination, but traces of N-alkylimidazole or acid may be present. 

The base-induced monodehydrochlorination reaction was originally introduced as the second step of a convenient two-step synthesis of methylenecyclopropanes from alkenes. The first step involves carbene-type cyclopropanation of the alkene with a 1,1-dichloroalkane and either butyllithium or sodium bishexamethyldisilazanide as the base. The dehydrochlorination is then carried out by reacting the intermediate 1-alkyl-1-chlorocyclopropane with potassium tert-butoxide in dimethyl sulfoxide. For ordinary unhindered chlorocyclopropanes this procedure gives from about 60% to nearly quantitative yields of products (Table 1). The ready availability of the starting materials and reagents makes the base-induced dehydrochlorination a most useful 1,2-elimination reaction for preparation of methylenecyclopropanes. The procedure is illustrated by the synthesis of l,l-dimethyl-2-methylenecyclopropane (3) from 2-methylpropene ( ) ... 

Imidazolium salts are precursors (preligands) of carbene ligands. In several cases, they can be directly submitted to the formation of metal complexes. Various approaches for the synthesis of imidazolium salts of types 1 and 2 are reported in the literature (Scheme 2.151) [23]. The most common synthesis of 1 is based on the Af-alkylation of l//-imidazole with alkyl halides in the presence of bases (sodium hydride, sodium or potassium hydroxide, or potassium tert-butoxide, route A). 1-Substituted imidazoles, usually Al-methylimidazol, are convenient starting materials to generate nonsymmetric imidazolium salts of type 1 by treatment with a second equivalent of alkyl or aryl halide [25]. 

Discrete copper compounds can also be used as catalysts for the synthesis of arylamines (Scheme 3.52) [58]. Venkataraman used a neocuproine-ligated copper(I) species to promote the coupling of aryl halides with secondary amines. A practical advantage to this chemistry was that only air-stable materials were needed to construct the catalyst needed for the cross-coupling. A base was needed to promote the reaction, and potassium tert-butoxide was found to be more effective in the cross-coupling than other common bases including potassium phosphate, sodium methoxide, or cesium carbonate. Curiously, cesium carbonate was not as active in this chemistry, but it was quite effective in the preparation of diaryl ethers. Several aryl halides were screened for activity, and aryl bromides and iodides afforded moderate to good yields of the arylamines. It should be noted that an electron-neutral aryl chloride was converted into the triarylamine, albeit in lower yield (49%). 

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