ahout 10O p o u n d s 5 0 0 0 space.
RESEARCH New Chlorine Analysis Is Faster Method to determine organically bound chlorine uses sodium a n d liquid anhydrous ammonia
X HE ANALYTICAL chemist has a
new
procedure to d e t e r m i n e chlorine in organic compounds. T h e new m e t h o d , developed by H e r m a n Beckinan of the Texas Agricultural Experiment Station, overcomes most of the drawbacks ot other known m e t h o d s ; it is general, inexpensive, and quick. The demand for an improved analytical technique came, in part, from the pesticide industry. Many pesticides contain b o u n d chlorine, and industry and government analysts needed a faster, cheaper method than the ones they w e r e using to determine the halogen. Beckman's technique may meet their requirements. The n e w method determines the other halogens as well. This is the Beckman procedure: Samples containing about one milliequivalent of chlorine are weighed into a beaker—the only vessel used during the entire procedure. Excess ammonia is then a d d e d to chill and dissolve the sample. To m a k e sure that the sample remains dissolved, ethyl ether is also added. T w o or three small pieces of metallic sodium (0.5 gram) are a d d e d t o reduce the chlorine to the chloride ion. T h e reduction is complete in about two minutes—indicated by appearance of a t>lue color. After the a m m o n i a and ether are evaporated, excess sodium combines with moisture in the air to form sodium hydroxide. W h e n this happens, the blue color disappears. The solution is then neutralized with nitric acid, and the chloride titrated with silver nitrate. End point is determined either amperometrically, potentiometrically, or visually, d e p e n d i n g on t h e desired accuracy. If sulfur is present in the sample, it is removed b y oxidation to sulfate with hydrogen peroxide and heat. This is done before t h e neutralization step. No WIUCM. 'p-icrcat-itujuia c».i C î I C C G c u χ υ ι
crxcr-
menfcs that might interfere w i t h chloride titration.
the
34
C&EN
APRIL
6,
1959
• Low Error. Accuracy of the method is good, seldom exceeding 3f < error. In most cases, t h e error is smaller—in tests of chlorine recovery from insecticides, error has never ex ceeded 2 Ο . Time required t o complete an analy sis is 30 minutes. And total manipula tion time is considerably less. Beckman points o u t , since evaporating the excess ammonia may take a s long as 20 minutes. Se\ era! samples, therefore, can h e run concurrently by one person. Beckman has also determined amounts of halogens in polymers such as polyvinylidene chloride, polyvinyl chloride, and polytetrafluoroethyleiie. In the latter, fluorine is determined gravimetrically as calcium fluoride after defluorination..
• N e w t w o - s t e p r o u t e to cyclohepta t r i e n e (used to prepare derivatives of Diels-Alder adducts) has been dis covered by Η . Ε. Win berg of D u Font {Journal of Organic Chemistry, 24, 264, (1959)]. Synthesis consists of first preparing T,7-dichlorohicyclc>[4.1.0]heptane (1) from dichlorocarbene and cyclohexene a n d then pyrolysis of the product to cycloheptatriene a n d tolu ene. Yield a t 500° C . is a mixture of 65'ί- toluene and 3 5 r/t cycloheptatriene. • Solid p r o p e l l a n t s developed by Her cules Powder will constitute t h e third and fourth stages of the space rocket, Scout. T h i r d stage will b e a scaled-up version of t h e third-stage engine in the Vanguard; f o u r t h stage ^vill be the engine d e v e l o p e d for t h e Van guard. Scout will be used for orbital a n d highaltitude shots by National Aeronautics and Space Administration; the Air Force plans t o u s e it to test guidance systems. Rocket is designed to put 150 pounds into orbit or send a paydoad of
miles
into
ψ F*>ur t e x t i l e firms and the Atomic Energy Commission a r e supporting a $27o,OOQ research project on t h e effects of n u c l e a r energy on fibers, fabrics, and textile processes. Study will be done at NTorth Carolina State College's school of textiles research. Companies spon soring t h e project—Burlington Indus tries, C o n e Mills, J. P. Stevens, and Reeves Brothers—will contribute 20r,'< of t h e funds; A E C will supply the re maining 8 0 V'. • P r i v a t e industry can now support fundamental research at the Mellon Institute. Institute's n e w plan is set up so t h a t companies can either sub scribe t h r o u g h grants-in-aid or by en tering i n t o contracts t o support funda mental research. • Error in the way the human body handles t h e triglycerides (chief constit uents of common food fats) may b e the most important abnormality in coronary artery disease, according t o M. J. Albrink of the American H e a r t Association. Albrink says this function may b e more important than how t h e body h a n d l e s cholesterol; in a study of 82 men w h o had suffered heart attacks, Albrink a n d coworker E. B. Man found that most of the men h a d normal cho lesterol levels in the blood, but two thirds h a d abnormal levels of triglyc erides. ÎAAerck S h a r p & Dohme g e t s t h e g o a h e a d from the National Institutes of Health to market Tetravax, a four-inone vaccine against polio, whooping cough, diphtheria, a n d tetanus. Company will be set to distribute the vaccine within a few weeks. • AAonsanto Chemical will supply d i e Air Force's Wright Air Development Center with a research quantity of a polypheny! ether. T h e Air Force will test t h e ether as a high temperature functional fluid. T h e ether is one of a series of compounds p r o d u c e d by Monsanto which remain liquid and keep lubrication characteristics at temperatures ranging from 20° to 800° F . C o m p a n y says they are two to five times m o r e stable under nuclear radiation t h a n are other existing organic lubricants.
