CH3 SH Research Articles

Ion—molecule reactions in hydrogen sulfide, methanethiol and 2-thiapropane

The ion—molecule reactions in H 2S, CH 3SH, and (CH 3) 2S were observed at pressures up to 400 millitorr, using a quadrupole mass spectrometer with a single electron-impact ion source. Rate constants were measured for the disappearance of most primary ions and the appearance of several secondary ions, and mechanisms are proposed for the reactions observed. In all three cases, the major ion produced was the M + 1 ion (where M represents the mass of the parent ion), which reacted further to give the 2M + 1 ion. Charge exchange between the neutral gas and primary ions to produce the parent ion was observed in CH 3SH and (CH 3) 2S and is suspected in H 2S. In the cases of CH 3SH and (CH 3) 2S, an additional reaction sequence originating with the (M − 1) ion was observed, while in H 2S an additional sequence originating with the S + ion was found.

Utilization of S-methylcysteine and methylmercaptan by methionineless mutants of neurospora and the pathway of their conversion to methionine I. Growth studies

1. 1. Seven of the eight methionineless auxotrophic Neurospora mutants grow substantially on S-methylcysteine as the sole soure of sulfur. 2. 2. The same seven mutants could also utilize methylmercaptan (CH 3SH) as a sole source of sulfur. The eighth mutant (a non-leaky me-5) required the addition of O-acetylhomoserine for growth on methylcysteine or methylmercaptan. 3. 3. Growth data provided evidence that methionine may be synthesized from O-acetylhomoserine and methylmercaptan derived from methylcysteine.

The vibrational spectra of methanethiol

The infrared spectra of CH 3SH and CH 3SD have been investigated in the gas, liquid and solid state with the purpose of resolving some inconsistencies in the fundamental frequency assignment of CH 3SH. A study of the Raman spectra of liquid CH 3SH and CH 3SD to complement the infrared results was also carried out. A modified valence force field which included the diagonal symmetrized force constants plus a single added repulsive interaction constant coupling the methyl wagging with the SH bending vibrations was used in a normal coordinate treatment. Excellent agreement between the observed and calculated frequencies was obtained.

Chemical effects following the 34S(n,γ) 35S reaction in gaseous-sulphur compounds

The chemical behaviour of 35S formed by the 34S( n, γ) reaction has been studied in gaseous H 2S, SO 2, SF 6, CH 3SH, and thiophene. We obtained the reaction by sealing the gases in quartz ampules and irradiating them with thermal neutrons in the Livermore pool-type reactor (LPTR). Among the effects studied were those of pressure, surface area, and additive gases including argon, nitric oxide, oxygen and hydrogen. The 35S was recovered in gaseous compounds and in deposits on the walls of the ampules; the chemical composition of both portions of activity was determined by aqueous chemistry using carriers. The results are consistent with a model in which the original molecule is broken up in the recoil process and the resulting fragments containing 35S react with the surroundings only after they have slowed to thermal energies; in general, the final chemical form of the 35S is determined by the chemical environment in which it is produced rather than by its original oxidation state or chemical form. However, irradiations of mixtures of several gases with NO gave results possibly indicating that the chemical form of the 35S immediately after molecular disruption may depend upon the nature of the original molecule.

The preparation and properties of silyl methyl sulphide

The new compound, SiH 3SCH 3, has been prepared from SiH 3I·N(CH 3) 3 and CH 3SH. Its physical properties have been studied. Using B 2H 6 as a reference Lewis acid, SiH 3SCH 3 has been found to be a weaker Lewis base than (CH 3) 2S. Diborane was not a sufficiently strong Lewis acid to differentiate between the relative base strengths of SiH 3SCH 3 and (SiH 3) 2S.