-5- 
This digest abstracts the articles included in the third list of 
publications on DDT (E-674) • The literature referred to in the first 
and second lists of publications on DDT has been reviewed in the first 
(E-631) and second (E-687) digests. Nearly 1,000 publications deal- 
ing with DDT which had appeared up to July 1, 1945, are covered in 
these three digests. 
DEFINITIONS 
M The term , DDT I refers to the tecnnical grade of 2,2-bis(parachloro- 
phenyl) 1,1,1-trichloroethane, which contains as impurities considerable 
amounts of isomers and much smaller amounts of other by-products formed 
in its manufacture. So far as we are now aware, the normal impurities 
in DDT are active ingredients within the meaning of the Insecticide Act 
of 1910. Therefore, its label is not required to bear an ingredient 
statement." — Reed (300 ). 
It is recommended that in the future the term ^p^'-DDD' 1 be used 
exclusively for reference to H 2,2-bis-(p-chlorophenyl)-l,l-diohloro- 
ethane. — Gunther (195). 
CHEMISTRY 
Synthesis 
The preparation of DDT in the laboratory is described in such a way 
that it can be performed as a regular experiment in the beginning course 
in organic cnemistry. 45 grams (0.2 mole) of monochlorobenzene and 34 
grams (slightly over 0.1 mole) of chloral hydrate are added to 350 grams 
of 95-percent sulfuric acid and 50 grams of 20-percent oleum; the mix- 
ture is stirred for 90 minutes, during which time the temperature rises 
to 45°C. The reaction mixture is poured into 2 liters of ice water and 
the solid product washed on a funnel under suction with cold water. The 
crude product is then melted in 500 ml. of boiling water, allowed to 
solidify by cooling, and the wash water removed by decantation. This 
process is repeated two additional times, and sodium bicarbonate is add- 
ed to the last wash water to remove the last traces of acid. The product 
is then collected on a suction filter and dried. The yield of crude ma- 
terial (m.p. about 90°C») is about 70 percent of theoretical. It can be 
purified by re crystallization from ethyl or propyl alcohol.— Darling (126 ) . 
The laboratory preparation of DDT according to Zeidler's procedure, 
using chloral hydrate instead of chloral, is described. The mixture is 
heated under a reflux condenser to 122°C. for Z\ to 3 hours, or is 
stirred with heating (not to exceed 105°) for 8 to 10 hours. — Bailes (80). 
Physical properties 
A procedure for determining the setting point of TDT is described. 
