Five alkyl and five aryl phosphorothioates are ranked relative to parathion in effectiveness as base-pair mutagens in the Ames mutagenic assay. Three in each series were mutagenic. Two commercial insecticidal phosphates, included for comparison, were mutagenic. The mutagenic phosphorothioates contained a strong electron-withdrawing and/or a good leaving group, together with two other groups small enough to permit nucleophilic attack by a biomacromolecule on the electrophilic phosphorus atom. All but one of the phosphorothioates [i.e., O,O,O-tris(2,2,2-trifluoro)ethyl phosphorothioate, VI] required metabolic activation for mutagenicity to be manifested; hence most of the phosphorothioates per se evidently are not ordinarily sufficiently electrophilic to be mutagenic but must instead be transformed to more electrophilic oxygen-containing products. In evaluation for cell-transformation properties, methyl parathion was inactive, in contrast to VI. The phosphorothioates that were novel were synthesized by formation of the phosphite from the appropriate alcohol or phenol, followed by reaction of the phosphite with sulfur.

No abstract

Amides of thiophosphoric acid were studied, in order to initiate correlations of mutagenicity with structure, by use of a modified Ames assay. Representative thiophosphoramides of the structure (XArNH),PS were not mutagenic, irrespective of whether X was a reference hydrogen atom, an electron-withdrawing, or an electron-donating group. One phosphoramidothioate of the structure (2,4-X,ArNH)P(S)(OCH2CH,), effected base-pair mutation when X was F (but not when X was CH,), when S-9 liver homogenate with exogenous NADP was used; when X was H, only inconsistent mutagenic activity following metabolic activation was observed even at concentrations near those that produced acute cellular toxicity. Mutagenicity of these N-arylamides thus appears to follow guidelines concluded for esters, (RO),PS, i.e. that mutagenesis is most probable when two groups are small enough to permit nucleophilic attack by a biomacromolecule on the electrophilic phosphorus atom. That the third group should be electron withdrawing again seems important although it need not be a good leaving group. An alkyl thionamide, ((CH,),N],PS, resembled the oxygen counterpart, [(CH,),N],PO, to which it probably is biotransformed, in being only marginally mutagenic. We conclude that the hazard of mutagenesis is likely to be less with amides than with esters of thiophosphoric acid and that most of the representative thioamides tested are unlikely to pose serious mutagenic hazards.

No abstract

Polybenzimidazoles have been extensively in~estigatedl-~ since they were first described in 1959.4 The outstanding thermal and chemical stabilities of this class of polymers have suggested broad utility in high-temperature films, laminates, adhesives, fibers, and insulating foams.Traditionally, polybenzimidazoles have been obtained by the reaction of aromatic tetraamines with dicarboxylic acids or their derivatives at high tern~eratures.'-~ In a two stage process for the preparation of poly[2,2'-( rn-phenylene)-5,5'bibenzimidazole], the final stage involves solid state polymerization at 385°C: A useful solution polymerization method has been described by Marvel utilizing refluxing sulfolane or diphenylsulfone as solvent? More recently, polyphosphoric acid has been utilized as a solvent for the preparation of a variety of polybenzimidazoles, polybenzoxazoles, and polybenzothiazoles?We recently reported' that polyamides derived from the reaction of bis(2-oxazolin-5-one)s (bisazlactones) and diamines readily cyclodehydrate thermally to produce polymers containing 2-imidazolin-5-one units. Seeking to utilize bisazlactones in the synthesis of other heterocyclic polymer systems, we considered azlactones as reagents to convert o-phenylenediamines into benzimidazoles. We now report the facile preparation of benzimidazoles from the reaction of azlactones and o-phenylenediamines, and the extension of this reaction to the preparation of poly(amide-benzimidazo1e)s. EXPERIMENTAL Measurements'H-and 13C-NMR spectra were recorded using a Varian EM360L, Jeol FX100, Varian XL200, or Varian XL400 spectrometer, under the conditions noted in Tables I and 11, using tetramethylsilane or DMSO-d, as an internal reference. Infrared spectra were obtained on a Perkin-Elmer 283B spectrophotometer. Melting point determinations were made using a Bristoline hot-stage microscope and are uncorrected. A Cannon-Ubbelohde viscometer was used to determine the inherent viscosity of polymer solutions with concentrations of 0.5 g/100 mL in DMF at 30 0.1'C. Materials2-Phenyl-2-oxazolin-5-one (9a),15 N-benzoyl-a-aminoisobutyric acid,',, l7 4,4-dimethyl-2-phenyl-2-oxazolin-5-one (9b)," N, N'-terephthaloylbis(glycine),'' N, N'-terephthaloylbis( a-aminoisobutyric acid)," 2,2-p-phenylenebis(2-oxazolin-5-one) (12a)," and 2,2'-p-phenylenebls(4,4-dimethyl-2-oxazolin-5-one) (12b)" were prepared according to literature procedures. 2,2'-rn-Phenylenebis(4,4-dimethyl-2-oxazolin-5-one) (12c), mp 125-127OC (lit." mp 129OC) was prepared by procedures analogous to those in the literature." 3,3',4,4'-Tetraaminobiphenyl was purified by sublimation (0.1 torr, 220°C) as yellow crystals, mp 181OC. Model Compounds N-Hippuryl-o-phenylenediamine (loa):A solution of o-phenylenediamine (3.36 g, 0.031 mol) in dry DMF (8 mL) was added to a vigorously stirred solution of 2-phenyl-2-oxazolin-5-one (5.0 g, 0.03 mol) in DMF (5 mL) at room temperature. After stirring overnight, the product was filtered, dried overnight in uacm, and crystallized from ethanol to give 1 O a in 95% yield: m...