VOLUME 2 -methyl-2 -thio

B. l-Phenyl-2-thiobiuret. A solution of 20.9 g. (0.1 mole) of l-phenyl-2-thio-4-methylisobiuret in 200 ml. of hot absolute ethanol is treated with 40 ml. of concentrated hydrochloric add, and the clear liquid is heated under reflux until no more methyl chloride is evolved (6-12 minutes. Note 4). The resulting solution is stirred into 2 1. of water, and the separated crystalline predp-itate is collected after storage at 0° for at least 24 hours. The dried product is dissolved in boiling absolute ethanol (5-6 ml. per g.), then the hot solution is quickly filtered by light suction and diluted with half its volume of petroleum ether (b.p. 60-80°). The separated l-phenyl-2-thiobiuret is collected by suction filtration after storage for 12 hours at room temperature, and rinsed-with small portions of a mixture of equal volumes of ethanol and petroleum ether. The yield of product, m.p. 159-161° (NoteS), is 8.8-10.5 g. (45-54%) (Note 6). 

The initials of TOET progressed quite logically from TOM, in an exact parallel with the relationship between the corresponding sulfur-free analogues, where the ethyl compound is DOET and the methyl counterpart is DOM. "T" for "thio" which is the chemical nomenclature term for the replacement of an oxygen atom with a sulfur atom. And, as has been discussed in the text of this volume, the peculiarities of pronunciation in this series are interesting, to say the least. TOM is no problem. But TOET could have any of several pronunciations such... 

Phosphazene chemistry is covered separately elsewhere within this volume but three notable papers involving theoretical and computational chemistry methods have been reported. Non-empirical RHF/6-31G and MP2/6-31G quantum chemical methods have been used to calculate the molecular structure of two trichlorophosphazenes (8) and (9). The corresponding geometric parameters obtained from the calculations were compared with XRD analysis data previously reported in the literature. Conformational differences between the two molecules, previously found by XRD analysis of the crystals, were confirmed by non-empirical quantum chemical calculations on the molecules in the free state and the features of their geometry were discussed. A DFT study of the structural organization and infrared spectra of hexakis 4-iV -dichloro(thio)phosphonyl-A -methyl-dia-zobenzene cyclotriphosphazene, a phosphorus-containing dendrimer built... 

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