A differential anomalous x-ray scattering technique has been developed for structural studies of disordered and amorphous systems. The results on amorphous GeSe 2 are consistent with the twofold coordination of Se and the fourfold coordination of Ge. The results on amorphous GeSe are consistent with threefold-coordinated models of the structure but not with the fourfold-twofold models.

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M iddlesex a-Carboline-I -oxide (I) with acetic anhydride gives 2-acetoxy-9-acetyl-a-carboline; with dimethyl sulphate it gives the salt (11; R = H ) . The latter salt is converted by alkali into the anhydronium base (111; R = OMe). The salt (11 ; R = H ) and the base (I11 ; R = OMe) are converted by sufficiently basic nucleophilic reagents into 2-substituted a-carbolines ; the salt (I1 ; R = Me) reacts even more readily with basic nucleophilic compounds.Diethyl malonate and ethyl acetoacetate with (111; R = OMe) give the ester ( V ; R = CH,CO,Et). The acid (V; R = CH,CO,H) is readily decarboxylated to 2-methyl-cr-carboline.The benzotriazole (IV; R1 = NOz, R2 = H ) in hot phosphoric acid does not give 3-nitro-a-carbo\ine, but gives instead Z-nitropyrido[1,2-a] benzirnidazole (VIII) ; the latter compound is also obtained by treating the amine (VII) with hydrochloric acid. However the benzotriazole (IV; R1 = NH2. Ra = H ) is converted by phosphoric acid into 3-amino-a-carboline ; the benzotriazole (IV; R 1 = H, Ra = C0,H) is similarly converted into a-carboline -4-carboxylic acid. The preparation and proof of orientation of some 6-substituted a-carbolines are described.The I H n.m.r. spectra of 2-, 3-, and 4-substituted a-carbolines are discussed.WE required substituted or-carbolines for pharmacological testing. Lawson, Perkin, and Robinson,la and later Freak and Robinson,lb prepared or-carboline from o-phenylenediamine and 2-chloropyridine by a modification of the Graebe-Ullmann synthesis. This method can be used to prepare, e.g., 2-and 4-methyl-a-~arboline,~ but it has not been widely usedJ3 and many apparently suitable 2-halogeno-pyridines are not readily available or do not react as chloropyridine does (we were unable, for example, to condense o-phenylenediamine with 2-chloro-6-hydroxypyridine or 2-chloro-6-ethoxypyridine) .By modifying the method of Robinson et al. in several minor respects (see Experimental section) we raised the reproducible overall yield of a-carboline to 21% (from o-phenylenediamine). Peracetic acid converted a-carboline almost quantitatively into the N-oxide (I). When (I) was heated under reflux with acetic anhydride, 2-acetoxy-9-acetyl-a-carboline was isolated in 65% yield. 2-Hydroxy-a-carboline was obtained from the product by hydrolysis; it was acetylated to give 2-acetoxy-a-carboline. However the N-oxide (I) was not attacked by boiling aqueous or ethanolic potassium cyanide or sodium hydroxide.We therefore prepared the salt (11; R = H) by heating the N-oxide (I) with dimethyl sulphate. We treated (11; R = H) with cold aqueous potassium cyanide, expecting to obtain a cyano-a-carboline (when similarly treated the salt obtained by the action of dimethyl sulphate on pyridine l-oxide or quinoline l-oxide 4+5 gives 2-cyanopyridine or 2-cyanoquinoline), but obtained instead a yellow oil that was not a nitrile. The same product was obtained when (11; R = H) was treated with aqueous sodium hydroxide. We next treated 1-methyl-a-carbolinium methyl sulphate with aqueous potassium cyanide and obt...

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X‐ray absorption spectra about the K edges of Ni, Cu and Ti have been measured at the Stanford Synchrotron Radiation Laboratory. The imaginary part of the atomic scattering factor f′′ was determined using the optical theorem and the real part f′ computed by the Kramers–Kronig dispersion relation. Methods for evaluating this integral as well as the effects on f′ of various experimental errors are investigated. The f′ results for Cu and Ni are compared to data from interferometry experiments.