Triethylbenzylammonium chloride TEBAC

Another modern modification involves coupling of UNs 30 and /1-ketoesters 36 in aqueous emulsion in the presence of an interphase catalyst triethylbenzylammonium chloride (TEBAC) (06JCM228). 

To a stirred solution of 50% aq NaOH (30 mL) was added triethylbenzylammonium chloride (TEBAC) (3.54 g, 15 mmol) followed by diethyl malonate (2.40 g, 15 mmol) and 1,2-dibromoethane (4.23 g, 23 mmol). The mixture was stirred for 1 h. After dilution with H2O (75 mL), the system was extracted with EtjO. The aqueous layer was acidified with coned aq HCl and extracted with EtjO. The organic layer was washed with brine and dried (MgSOJ. Evaporation of the solvent gave cyclopropane-1,1-dicarboxylic acid yield 1.74 g (75%) mp 134-136 C. 

Alkynes react with various dichlorocarbene reagents to give 3,3-dichlorocyclopropenes 1, which can be hydrolyzed to cyclopropenones 2 in situ. The carbene reagents used are (A) chloroform, 50% sodium hydroxide, and triethylbenzylammonium chloride (TEBAC) (B) (bromo-dichloromethyl)phenylmercury (C) chloroform and potassium tert-butoxide and (D) chloroform and butyllithium. Although the yields of these reaction generally do not exceed 20%, a variety of cyclopropenones have been prepared by this method. The yields of biscyclo-propenones from diynes are very low. 

Alkylations of phenol derivatives were studied in solid-liquid phase using K2CO3 as a base under MW conditions, and it was observed that the 0-selectivity was enhanced in the presence of triethylbenzylammonium chloride (TEBAC) as the phase-transfer catalyst, thereby indicating the phenomenon of synergism in respect of MW irradiation and the phase-transfer catalyst [41-43]. 

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