Paralysis in man and the domestic fowl caused by "ToCP" (tri-cresyl phosphate, tri-tolyl phosphate or TTP) is reviewed, and the search for a non-toxic plasticizer derived either from TTP or tri-xylenyl phosphate (tri-dimethylphenyl phosphate or TXP) is described. It had been previously shown that the ortho-tolyl esters are toxic but we found that their removal does not make the mixture non-toxic. The meta-and para-tolyl esters were known to be free from toxic effects and the 2: 4 and 2: 5 dimethylphenyl esters were equally shown to be non-toxic except in massive doses. We confirmed that the tri-ortho-ethylphenyl ester was non-toxic, but found the mono-and di-ortho-ethylphenyl phosphates to be highly toxic. We showed that 1TP made from phenols with all the ortho-cresol and ortho-ethylphenol removed is non-toxic.With TXP, however, elimination of all ortho-cresol and ortho-ethylphenol from the raw materials does not result in a non-toxic plasticizer. Tri-ortho-n-propylphenyl phosphate was shown to be non-toxic but esters containing one or two ortho-propylphenyl groups are toxic.The toxicity of the ortho-tolyl, ortho-ethylphenyl and ortho-propylphenyl groups is much reduced in the presence of the 3: 5-dimethylphenyl group. This influence is greatest in mono-ortho-propylphenyl-di-3: 5-dimethylphenyl phosphate which is non-toxic in five consecutive daily doses of 500 mg,/kg. body weight.The removal of all ortho-cresol, ortho-ethylphenol and ortho-propylphenol from the raw material results in a non-toxic product which we termed non-toxic plasticizer "NTP". This has been fed in various doses to a variety of mammals and a large number of chickens in short term tests without toxic effects.Our experiments showed that tri-meta-ethylphenyl phosphate is non-toxic but tri-paraethylphenyl phosphate is highly toxic. The mixture from which NTP is made contains 10% of para-ethylphenol. Based on chemical statistics the tri-para-ethylphenyl ester can be present only in minute qu,antities, and we have shown that esters containing one or two para-ethylphenyl groups are non-toxic. An ester with a methyl group in the ortho, and an ethyl group in the para position in the same benzene nucleus (tri-2-methyl-4-ethylphenyl phosphate) we showed, surprisingly, to be non-toxic.
Summary
Ten maleinated jojoba oil derivatives were screened as plasticizers in a standard polyvinyl resin formulation and as softeners for Buna‐N rubber. Three of these, the methyl and butyl esters and hydrogenated methyl esters of maleinated jojoba acids, were comparable to the reference standard, DOP, as primary plasticizers for the vinyl resin. Three others were satisfactory only as secondary plasticizers. Six of the derivatives were comparable to the reference softener, dibutyl sebacate, as softeners in a Buna‐N formulation and yielded rubbers meeting the low temperature flexibility requirements (−40°C.) of the automotive industry. Two of the six, those made with the butyl and hydrogenated butyl esters of maleinated jojoba acids, met the still more stringent low‐temperature requirements of the aircraft industry (−55°C.).
In general, hydrogenation of a derivative adversely affected its compatibility in either the vinyl copolymer or the Buna‐N formulations.
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