Tetraethyl development

Phosphoric Acid and Phosphorothioic Acid Anhydrides. The aUphatic organophosphoms esters originally developed by Schrader (27) are extremely toxic to mammals and are largely of historic interest. Tetraethyl pyrophosphate [107-49-3] (40) (bp 104—110°C at 10.7 Pa, d 1.185, vp 6.1 mPa at 30°C) is miscible with water and hydrolyzes very rapidly with a half-life of 6.8 h at 25°C. The rat LD qS ate 1.1 (oral) and 2.4 (dermal) mg/kg. 

A.sahi Chemical EHD Processes. In the late 1960s, Asahi Chemical Industries in Japan developed an alternative electrolyte system for the electroreductive coupling of acrylonitrile. The catholyte in the Asahi divided cell process consisted of an emulsion of acrylonitrile and electrolysis products in a 10% aqueous solution of tetraethyl ammonium sulfate. The concentration of acrylonitrile in the aqueous phase for the original Monsanto process was 15—20 wt %, but the Asahi process uses only about 2 wt %. Asahi claims simpler separation and purification of the adiponitrile from the catholyte. A cation-exchange membrane is employed with dilute sulfuric acid in the anode compartment. The cathode is lead containing 6% antimony, and the anode is the same alloy but also contains 0.7% silver (45). The current efficiency is of 88—89%, with an adiponitrile selectivity of 91%. This process, started by Asahi in 1971, at Nobeoka City, Japan, is also operated by the RhcJ)ne Poulenc subsidiary, Rhodia, in Bra2il under Hcense from Asahi. 

Currently available CRMs A number of organolead (tetra- and triaUcyllead) compounds are commercially available to be used as calibrants. There are also a number of interesting CRMs an urban dust certified for trimethyUead and more appear to be in development The interest in organolead compotmds is, however, on the decline due to the gradual disappearance of the tetraethyl anti-knock agent from petrol. 

The importance of methods of analysis for new insecticides is evidenced by the fact that during the past two years industry and government have cooperated in developing methods for two of them—tetraethyl pyrophosphate and benzene hexachloride (1,2,3,4,5,6-hexachlorocyclohexane) (37, 45). 

Several chemical-assay methods (15,23,50) for tetraethyl pyrophosphate were recently developed and applied by seven collaborating laboratories to samples of representative commercial products and to a sample of purified tetraethyl pyrophosphate which served as a common standard. Concordant results, which correlated well with bioassay results,... 

Catalysts were expensive, however, so the petroleum industry did not solve the problem of cheap, lead-free, knock-free gasoline until the 1970s, after General Motors adopted the catalytic converter. Lead compounds inactivate the catalysts, and sophisticated catalytic cracking techniques had to be developed to replace the fuel additive. Ironically, an even more difficult job was finding a substitute for the protective coating that tetraethyl lead formed on exhaust valve seats not even newly developed, extremely hard materials prevent wear and tear on them as well as tetraethyl lead did. 

Motors support for a long-range scientific study of the poisonous gasoline additive, tetraethyl lead. Besides trouble-shooting for various Du Pont departments, Carothers published 60 papers and was listed as the inventor or coinventor of 69 U.S. patent applications during his nine years at Du Pont. Research and development were so new to American corporations that Carothers assistants drafted and he edited patent applications for Du Pont lawyers. You were supposed to be so on top of the literature that you knew whether this was something new or not.. . . Those patents are really classical scientific papers, Hill explained. Carothers considered himself unfit to be a clerk or inventor, but he dominated Du Pont s patent application process for almost a decade. 

Kehoe was a smooth and practiced expert witness at government and judicial hearings. He opened his testimony by boasting that he knew more about lead than anyone else in the world. He boasted that he had served as the Ethyl Corporation s medical director because I was the only person who was familiar with the toxicology of tetraethyl lead and with the occupational hazards associated with its manufacture and distribution.. . . In developing the information on this subject (lead), I have had a greater responsibility than any other person in this country. Kehoe proudly... 

A further fact must be taken into account, which for obvious reasons did not appear in Haslam s article. As a consequence of our contracts with the Americans, we received from them above and beyond the agreement many very valuable contributions for the synthesis and improvement of motor fuels and lubrication oils, which just now during the war are most useful to us. It need not be especially mentioned that without lead-tetraethyl the present method of warfare would be unthinkable. The fact that since the beginning of the war we could produce lead-tetraethyl is entirely due to the circumstances that, shortly before, the Americans had presented us with the production plans, complete with experimental knowledge. Thus the difficult work of development (one need only recall the poisonous property of lead-tetraethyl, which caused many deaths in the U.S.A.) was spared us, since we could take up the manufacture of this product together with ail the experience that the Americans had gathered over long years. 

Later, Thangaraj et al. (275,281) developed a novel, improved route (prehydrolysis method) for the preparation of good quality TS-1 samples. In this method the silica source (tetraethyl orthosilicate TEOS) in Ao-propanol was first hydrolyzed with 20% aqueous TPAOH solution prior to the (dropwise) addition of titanium butoxide in dry iso-propanol under vigorous stirring. Crystallization was done statically at 443 K for 1-5 days and the solid was calcined at 823 K for 10 h. The TS-1 samples thus obtained exhibited high catalytic activity in hydroxylation reactions. 

Wiese Formula An empirical formula developed by General Motors Research for expressing motor fuel antiknock values above 100. This value is obtained by measuring the number of milliliters of tetraethyl lead added per gallon to achieve the same knocking tendency as the fuel being tested. The determined value is then expressed as a performance number. 

The first suggestion of a practical form of antidotal therapy came in 1949 from Hestrin, who found that acetylcholinesterase (AChE) catalyzed the formation of acetohydroxamlc acid when incubated with sodium acetate and hydroxylamine. Critical in vitro studies in the next decade led to the development of a practical approach to therapy. The crucial concept in these studies was the recognition that the compound formed when AChE reacted with a phosphorus ester was a covalent phosphoryl-enzyme Intermediate similar to that formed in the hydrolysis of acetylcholine. 3 Wilson and colleagues, beginning in 1951, demonstrated that AChE inhibited by alkyl phosphate esters (tetraethyl pyrophosphate, TEPP) could be reactivated by water, but that free enzyme formed much more rapidly in the presence of hydroxylamine. 0 21 Similar results... 

Organolead Compounds. Methods for sampling and analysis of tetraethyl lead and tetramethyl lead were developed based on collection on XAD-2, desorption with pentane, and analysis by gas chromatography with a photoionization detector. 

Investigations showed that the salts of other alkali metals are not so efficient in suppressing secondary flame as potassium salts. Fairly numerous experiments were carried out to clear up whether or not known antiknock substances, such as tetraethyl lead or nickel carbonyl prevent the development of a secondary flame. They proved to have no effect on its development. In practice, two methods for removing gun-flash may be employed, i.e. either a special flashless powder is produced, containing nitroguanidine or DNT and a small admixture of potassium sulphate,... 

To a suspension of UDP (4.5 mmol) in toluene (10 ml) in a laboratory ultrasonic cleaning bath under N2 was added a solution of 2,2,5,5-tetraethyl-3-sulfolene (1.5mmol) in toluene (10ml). The sonication was continued for 30 min, during which time a bright-blue colour developed. A solution of t-BuOH in THF (0.45 mol dm"3,4.4 mmol) was added dropwise over a period of 30 min, whereupon the potassium was completely consumed. The mixture was filtered through a short silica gel column to remove the solid precipitate, and the filtrate was concentrated under reduced pressure. Purification by HPLC (Lichrosorb column, hexane) yielded the corresponding diene in a 92% yield. 

Refining with chemical solutions and synthesis and use of oxidation inhibitors started in late 1920s 19. Development of processes of dehydrogenate u-paraftins to M-olefiiLs and alkylate benzeue with them (mid- 1960s) Discovery of tetraethyl lead (1921)... 

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