Methyl chloride absorption spectrum

Worenine. This alkaloid, also obtained by Kitasato from Coptis japonica was isolated as the tetrahydro-base, C,oHjg04N, which crystallises from alcohol in colourless prisms, m.p. 212-3°, and is oxidised by iodine in alcohol to worenine iodide, yellow crystals from which worenine chloride, thin orange-yellow prisms, m.p. 295° (dec.), can be obtained. Tetrahydro-worenine behaves as a tertiary base, contains methylenedioxy- but no methoxyl groups, and its absorption spectrum closely resembles that of tetrahydrocoptisine from which it differs in empirical composition by. CHj. Worenine is, therefore, represented by (XXX), the alternative position (a) for the methyl group being untenable, since a-methyltetra-hydrocoptisine obtained by Freund s method is not identical with... 

Secondary reactions then follow involving these and subsequently formed radicals. The nature of the species formed in the primary photolytic act has been inferred from the product distribution and other kinetic evidence, and also from observations of transient spectra during flash photolysis studies. For example, spectra characteristic of CIO, BrO, and 10 have been observed following the flash photolysis of methyl chloride , methyl bromide and methyl iodide in the presence of oxygen, and the absorption spectrum of the free methyl radical has been ob-served during the flash photolysis of methyl iodide and methyl bromide. 

If the concentration of methyl chloride is raised (6b Ar = 1 10), no IR bands of n-adduct T-5b or silylene S-lb can be detected. But T-5b has to be present in the matrix since in the UV spectrum the band at 260 (strong) is observable, together with a second absorption at 330 nm (weak), which we also attribute to n-adduct T-Sb. Upon irradiation with 330 nm the band at 260 nm disappears. At the same time a new absorption, again at 330 nm, can be detected. If one compares with the IR results (see below), it has to be concluded that this band belongs to adduct 7b, which is formed from the primarily generated uncomplexed silylene S-lb. Upon irradiation of the matrix with 330 nm light the IR bands of dichlorodimethylsilane 8b appear. Obviously, during irradiation a... 

Quinoxalin-2-ones are in tautomeric equilibrium with 2-hydroxy-quinoxalines, but physical measurements indicate that both in solution and in the solid state they exist as cyclic amides rather than as hydroxy compounds. Thus quinoxalin-2-one and its A -methyl derivative show practically identical ultraviolet absorption and are bases of similar strength. In contrast, the ultraviolet spectra of quinoxalin-2-one and its 0-methyl derivative (2-methoxyquinoxaIine) are dissimilar. The methoxy compound is also a significantly stronger base (Table II). Similar relationships also exist between the ultraviolet absorption and ionization properties of 3-methylquinoxalin-2-one and its N- and 0-methyl derivatives. The infrared spectrum of 3- (p-methoxy-benzyl)quinoxalin-2-one (77) in methylene chloride shows bands at 3375 and 1565 cm" which are absent in the spectrum of the deuterated... 

Mercapto-l,2,4-thiadiazoles are distinctly acidic. The pK of 5-thio-3-methyl-l,2,4-thiadiazole at 25°C is 5.18 <65AHC(5)119>. The position of equilibrium in the tautomers of 5-thio-l,2,4-thiadiazoles (10) (R = H) appears to be on the thione side (11) or (12). The solid state IR spectrum of (10) (R = Ph) shows no sign of SH absorption <92PS(66)32i>. However, treatment of (10) (R = Ph, / -Tol) with diazomethane does not produce any A-methylated products, but only the 5-methyl derivatives (137) (R = Ph, /)-Tol). Methylation of (10) (R = Ph) with methyl sulfate and with methyl iodide in sodium hydroxide gives only the S-methyl derivatives (137) (Scheme 31) <92PS(66)321>. In 1989 Yousef et al. reported that (10) (R = Ph) reacted with aromatic sulfenyl chlorides and with formaldehyde to give the A-substituted products (26) and (27) (Scheme 31). At the same time, alkylation... 

Mesoionic 4-amino-l,2,3,5-thiatriazoles constitute the only class of mesoionic 1,2,3,5-thiatriazoles known. They are prepared by the reaction of l-amino-l-methyl-3-phenylguanidine with approximately 2 equivalents of thionyl chloride with pyridine as solvent (88ACS(B)63>. They are obtained as the yellow 1 1 pyridine complexes (17). The dark-violet mesoionic 1,2,3,5-thiatriazole (18) was liberated on treatment with aqueous potassium carbonate (Scheme 3). The structure is established on the basis of elemental analysis and spectroscopic data. In particular, the IR spectrum is devoid of NH absorptions. Compound (18) exhibits a long-wavelength absorption at 463 nm in methanol. When mixed with an equivalent amount of pyridinium chloride, complex (17) is formed and the absorption shifts to 350 mn. The mesoionic thiatriazoles are sensitive towards mineral acids and aqueous base and although reaction takes place with 1,3-dipolarophiles such as dimethyl acetylene-dicarboxylate, a mixture of products were obtained which were not identified. 

Fig. 2 Transient spectrum taken in the ns-laser photolysis (15 mJ)of a 02 purged solution of 10"3mol dm"3 4-methyl-2,6-di-tert.-butylphenol in n-butyl chloride taken ( ) 10 ns and (>) 8 s after the pulse. The inset shows the photonity in the transient maxima where the 450 nm curve was threefold amplified (absorption given for I0= 300 mV).

Melinonine B is formulated as C2oH2 N20+ on the basis of analyses of the chloride, iodide, and perchlorate the chloride, mp 311° (dec.), has [a]D —14.8° (methanol-water) (54). The alkaloid has one A-methyl group but no methoxyl or (7-methyl groups. Its UV-spectrum is that of a 2,3-disubstituted indole and its IR-spectrum exhibits both hydroxyl (3.05 /x) and N—H (3.20 /x) absorption. Acetylation of melinonine B gives a crystalline 0,A-diacetyl derivative which results from attack at the indolic Na, since the UV-spectrum of this derivative is that of an A-acylindole and its IR-spectrum has both ester and amide bands. 

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