Envirocats

It years, there has been a considerable growth of interest in the catalysis of organic IS by inorganic reagents supported on high surface areas, Envirocat, a new family of supported reagents, which exhibits both Bronstead and Lev/is acid character, are ideal for environmentally friendly chemistry. These reagents are non-toxic powders that can be easily... 

Zinc chloride exchanged clay catalysts have been reported to be highly active for the Friedel-Crafts alkylation and acylation reactions these are commercially sold by Contract Catalysts under the name Envirocats. These are montmorillonite catalysts modified by ZnCU and FeCli. Some of the reported examples of Friedel-Crafts reactions are given below there are claims that some of the processes are commercially practised. 

Acylation reactions. Methoxyacetophenones and methoxypropiophenones can be obtained from acylation of methyl phenyl ether with the corresponding acid anhydrides and acid chlorides at 70 "C over Envirocat EPZG in 35 to 72 % yield. Other important reactions catalysed by this catalyst include acylation of PhNHCOCHi to acetamidoacetophenones and 1,3,5-trirnethylbenzene to 1,3,5- trimethylacetophenone. 

Alkylation reactions. In a laboratory procedure for the alkylation of benzene with benzyl chloride using the catalyst EPZIO at room temperature 100% conversion of the alkylating agent in less than 15 minutes was obtained (Envirocats, 1990). EPZE was efficiently used in the sulphonation of o-xylene with benzenesulphonyl chloride to give 3,4-... 

Envirocats, 1990, Envirocats Supported Reagents, Contract Chemicals, Knowsely, Merseyside, UK. 

MW-expedited dehydration reactions using montmorillonite K 10 clay [70] (Schs. 6.20 and 6.21) or Envirocat reagent, EPZG [71] (Schs. 6.20 and 6.21) have been demonstrated in a facile preparation of imines and enamines via the reactions of primary and secondary amines with aldehydes and ketones, respectively. The generation of polar transition state intermediates in such reactions and their enhanced... 

Varma, R.S. and Dahiya, R., Microwave-assisted facile synthesis of imines and enamines using envirocat EPZG as a catalyst, Synlett, 1997, 1245. 

Keywords benzaldehyde, aniline, ketone, secondary amine, Envirocat EPZG, microwave irradiation, imine, enamine... 

A mixture of benzaldehyde 1 (0.53 g, 5 mmol), aniline 2 (0.47 g, 5 mmol) and Envirocat EPZGR (100 mg) is placed in a small beaker inside the alumina bath (heat sink) and the contents are irradiated in a MW oven at full power for 1.0 min the reaction is monitored by TLC (hexane-AcOEt, 10 1). The product is extracted into dichloromethane (10 mL) and Envirocat EPZGR is removed by filtration and washed with dichloromethane (3xl0mL). Removal of the solvent on a rotary evaporator affords the benzylidene aniline 3 in 97% yield. 

Keywords aldehyde, acetic anhydride, microwave irradiation, Envirocat EPZ10, 1,1-diacetate... 

To a clean reaction vessel add benzaldehyde (0.53 g, 5.0 mmol), aniline (0.61 g, 10 mmol), and Envirocat EPZG (0.10 g), which is dried by distillation with tolune prior to the reaction. 

Extract the product into dichloromethane (10 ml), remove Envirocat EPZG by fitrtation and wash it with dichloromethane (3 x 10 ml). 

Envirocats , Contract Catalysts, Knowsley Industrial Park, Prescot, Merseyside, UK. 

Zeolite Y, Envirocat EPZG," CAN, silica gel, Montmorillonite clay K 10 or KSF, InBrs/polyethylene glycol, " Fe2(S04)3-xH20, " Well-Dawson heteropolyacid,CBr4, SnCL 21120,NaHS04, polyethylene glycol. ... 

Envirocat EPZIO was obtained from Contract Chemicals, England, and used without activation. A mixture of the aldehyde (5 mmol), acetic anhydride (10 mmol) and Envirocat EPZIO (1(X) mg) was irradiated with microwaves. After completion of the reaction (TLC), diethyl ether (2x10 mL) was added to the reaction mixture, and EPZIO was filtered off. After drying (Na2S04), the ether was evaporated under reduced pressure to give the products in high yield and in almost pure form. 

This method prevented side reactions that occurred when zinc chloride was used in tetrahydrofuran. With no zinc chloride at all, the reaction was sluggish. Metal chlorides, as well as protonic acids, on such supports are sold by Contract Chemicals in England as Envirocats (short for environmentally friendly catalysts), 37 They are stable to air. One of them has been used to dehydrate an oxime to a nitrile (5.4).38... 

The use of inorganic supports for Bronsted and Lewis acids25 was described in Chap. 5. These included the metal chlorides, as well as protonic acids, on inorganic supports that are sold by Contract Chemicals as Envirocats 26. They are air-stable, nontoxic powders that can be reused several times. 

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