Sulfur structures with

Amorphous or "plastic" sulfur is obtained by fast cooling of the crystalline form. X-ray studies indicate that amorphous sulfur may have a helical structure with eight atoms per spiral. Crystalline sulfur seems to be made of rings, each containing eight sulfur atoms, which fit together to give a normal X-ray pattern. 

Condensation of (chloroformyl)-sulfur chloride with 2-aminOthiazole gives a product (170) whose structure was established by X-ray analysis (Scheme 108) (352-354). 

The mobility of the proton in position 2 of a quaternized molecule and the kinetics of exchange with deuterium has been studied extensively (18-20) it is increased in a basic medium (21-23). The rate of exchange is close to that obtained with the base itself, and the protonated form is supposed to be the active intermediate (236, 664). The remarkable lability of 2-H has been ascribed to a number of factors, including a possible stabilizing resonance effect with contributions of both carbene and ylid structure. This latter may result from the interaction of a d orbital at the sulfur atom with the cr orbital out of the ring at C-2 (21). 

Treatment of biphenyl (see Section 11 7 to remind yourself of its structure) with a mixture of nitric acid and sulfuric acid gave two principal products both having the molecular formula C12H9NO2 What are these two products ... 

C.-H. Kiang e o/.[33] reported that the singlelayered coiled lubes were obtained by co-vaporizing cobalt with carbon in an arc fullerene generator. A single-layered helical structure with radii of curvature as small as 20 nm was seen. These helically coiled forms lend to bundle together. In the soot obtained with sulfur-containing anodes, they also found the 1.3-nm diameter lube coil around the 3.6 nm tube (see Fig. 14). This kind of structure was theoretically proposed in ref. [14]. 

The TJV spectra were measured for practically all the numerous derivatives. Beside the analytical application of these to demonstrate the position of the substituent no detailed interpretation was attempted, however. On the whole, they are similar to the spectra of analogous purine derivatives and also display a similar dependence on Despite the fact that the question of structure with regard to the lactim-lactam (or thiolactim-thiolactam) tautomerism has not been studied in detail, it can be assumed that oxygen and sulfur derivatives, at variance with the conventional way of writing the formulas, possess a lactam or thiolactam structure. This is in agreement with the views on the analogous purine derivatives. 

This compound was prepared by Allen et who found it to be monobasic and to form a simple methiodide. Attempted Hofmann degradation of this methiodide failed to give any information. The dimer was found to be perfectly stable to hot aqueous sulfuric acid. With the foregoing data, and by analogy with the alkyl pyrrole dimers, they proposed structure (9) for the dimer. Later work confirmed this structure by conversion via the methiodide into base (10) which was synthesized by way of the metho salt (11), isomeric with... 

The skeleton structure, with sulfur as the central atom, is... 

The water is added in order to hydrolyze the a-bromodimethyl ketals that have been produced during the reaction. The ease of hydrolysis of these bromoketals depends on the structure of the ketone. With aeetylcyclohexane (1-cyclohexylethanone) or acetylcyclopentane, stirring with water for 10 minutes is sufficient for complete hydrolysis. In contrast, with phenylacetone (1-phenylethanone) or methyl ethyl ketone (2-butanone), after dilution with water, the addition of 10 equivalents of concentrated sulfuric acid with respect to ketone and stirring for 15 hours at room temperature are necessary for complete hydrolysis. 

The reaction of vegetable oils, especially castor oil, with sulfuric acid to obtain wetting agents for the so-called Turkish red oil dying process has long been known. Therefore attempts soon were made to extend this procedure to other OH-containing structures and to replace sulfuric acid with phosphoric acid [ ] ... 

For sulfur dioxide, with resonating Lewis structure... 

The normal valence (normal covalence) of sulfur, corresponding to its position in the periodic table, is 2. The electronic structure of the normal bicovalent sulfur atom is the argononic structure with bond orbitals about... 

Galena, PbS, has the sodium chloride structure, with ligancy 6 for each atom. The Pb-S distance is 2.968 A. A possible structure is that based on the normal sulfur atom... 

A transargononic structure for sulfur, with six bonds formed by sp3d2 hybrid orbitals, was suggested for sulfur in the octahedral molecule SF6 long ago, and also for one of the sulfur atoms, with ligancy 6, in binnite (Pauling and Neuman, 1934). Some transargononic structures of metal sulfides have been proposed recently by Franzen (1966). 

In covellite, CuCu2SS2, the disulfide sulfur atoms have a tetrahedral quadricovalent argononic structure, with S— S = 2.09 A and S—Cu(I) =2.30 A. The sulfide sulfur atom has ligancy 5, with the bonds directed toward the corners of a trigonal bipyramid, as expected for S+ with dsp3 bonds (analogous to P in PCI5). 

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