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THOMAS T. CASTONGUAY and RICHARD L. FERM Chemical Engineering Department, University of Kansas. Although considerable private development has been carried out on the preparation of DDT, 1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane, little data on the production of this compound has appeared in the literature. The classic and original synthesis by Zeidler'12) in 1874 is used as a basis for present day commercial production. Directions for the preparation of DDT on a laboratory scale by the condensation of chloral, or chloral hydrate, with chlorobenzene using sulfuric acid as a catalyst have been given by Zeidler,'12) Miiller,'10) Hughes, (7,8) Iris and Leyva,(9) Bailes, (1) and Darling.(8) Rueggeberg and Torrans"'" have used chlorosulfonic acid in place of sulfuric acid. In 1943 Brothman and Barish(2) designed a pilot plant for the continuous production of DDT using chloral, oleum, and an excess of chlorobenzene. Several different isomers are possible. According to Gunther,5") technical DDT produced by the Brothman continuous process contains 70% of the p,p'-isomer, 18% of the o,p'-isomer, and 6% of the o,o'-isomer, the balance being ash, volatile, and unidentified material. The composition of technical DDT has been studied by Haller and co-workers.(6)

At the present time almost all DDT, 1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane, produced commercially is made by a process based on the classic and original synthesis of Zeidler.(4) This method consists of condensing chloral or chloral hydrate with chlorobenzene through the action of concentrated sulfuric acid or oleum. Several isomers are possible. According to Gunther,(2) technical DDT produced by the Brothman continuous process contains 70% of the p,p'-isomer, 18% of the o,p'-isomer, and 6% of the o,o'-isomer, the balance being ash, volatile, and unidentified material. Little mention has been made in the literature of new methods of synthesizing DDT. A student at the Fresno State College(') is said to have used zinc chloride in place of sulfuric acid as a condensing agent, but this has not yet been confirmed by other reports. Rueggeberg and Torrans(3) have condensed chloral hydrate and chlorobenzene through the action of chlorosulfonic acid to produce a 77% yield of DDT. In order to obtain satisfactory yields of DDT by the condensation of chloral with chlorobenzene through the action of sulfuric acid, a large excess of acid and chlorobenzene are necessary. The object of this paper is to investigate the use of other condensing agents and the use of inert solvents. Zinc chloride, thionyl chloride, sulfuryl chloride, phosphoric acid, and phosphorus pentoxide were tried as condensing agents. Inert solvents such as carbon tetrachloride, chloroform, carbon disulfide, and skelly solvent were used as solvents for the DDT during its preparation using sulfuric acid as a condensing agent.