Primary benzene solutions

For the benzene test program, three primary benzene solutions were prepared one was fully saturated with water, another was saturated with water and hydrochloric acid, and the third solution was only partially saturated. These primary solutions were mixed in various proportions to provide a wide range of concentrations for the static tests. 

A different mode of reaction, however, is observed in photoreductions of nitroaromatics by aromatic tertiary amines. Irradiation of benzene solutions of N-methylated anilines and either m-chloronitrobenzene or 1-nitronaphthalene results in oxidative demethylation of the amines accompanied with reduction of the nitro compound to the corresponding arylamine 49). The authors suggest that hydrogen abstraction from the methyl group takes place as the primary chemical event. 

The air oxidation of phenylacetylene and secondary amines in the presence of cupric acetate in benzene solution yields ynamines [22], This reaction requires only catalytic amounts of cupric salts and gives high conversions in less than 30 min when the Cu+2/phenylacetylene ratio is only 0.02. Only 1,4-diphenylbutadiyne is produced if the stoichiometric amount of cupric ion is used in the absence of oxygen. The yield of ynamine can be increased from 45 to 90 % if the stoichiometric amounts of a reducing agent such as hydrazine are continuously added during the course of the reaction. The use of primary amines under similar conditions yields the acetamide derivative. 

Co-oxidation of indene and thiophenol in benzene solution is a free-radical chain reaction involving a three-step propagation cycle. Autocatalysis is associated with decomposition of the primary hydroperoxide product, but the system exhibits extreme sensitivity to catalysis by impurities, particularly iron. The powerful catalytic activity of N,N -di-sec-butyl-p-phenylenediamine is attributed on ESR evidence to the production of radicals, probably >NO-, and replacement of the three-step propagation by a faster four-step cycle involving R-, RCV, >NO, and RS- radicals. Added iron complexes produce various effects depending on their composition. Some cause a fast initial reaction followed by a strong retardation, then re-acceleration and final decay as reactants are consumed. Kinetic schemes that demonstrate this behavior but are not entirely satisfactory in detail are discussed. 

Co-oxidation of indene and thiophenol takes place readily if the reactants in benzene solution are shaken with oxygen at temperatures in the range 20° to 40°C. (7). The major primary product has been shown to be frans-2-phenylmercapto-1 -indanyl hydroperoxide, I, which rearranges spontaneously to the two racemes of frans-2-phenylsulfinyl-l-indanol, II (8), and a tentative reaction scheme involving a three-step radical chain based on the suggestion of Kharasch, Nudenberg, and Mantell (11) was proposed for the formation of I. These three products accounted for 86% of the oxygen absorbed. 

If the oxychloride is applied in dilute benzene solution some nitrogen selenide or selenium nitride is also formed.3 With liquid ammonia in the presence of ether in open vessels, the primary product is the compound SeOCl2.4NH3, which is decomposed by water into selenium, selenium nitride, ammonium chloride, ammonium selenite and selenious acid in a sealed tube, selenium nitride is formed in comparatively good yield.4... 

Sommer and Bauman investigated the reaction of optically active a-naphthylphenylmethylsilyl hydride with trityl chloride and found that the stereochemical course was retention in benzene solution, inversion in methylene chloride, and full racemization in methylene chloride (93). The result in CH2C12 was explained as consistent with an exchange in which electrophilic attack on the silicon hydride by a triphenyl cation is of primary importance however, the counterion appears in the transition state [Eq. (16)]. Racemization of the unreacted R3SiH could arise from... 

Wasserman and co-workers investigated the photolysis of benzo-phenone diazide (31) in a rigid matrix at 77°K by observing the e.s.r. spectra of the photoproducts. At the onset of irradiation the signal of an azido nitrene appeared, prolonged photolysis resulted in diphenyl-methylene radicals. Irradiation of benzophenone diazide (31) in benzene solution at normal temperature produced 2-phenyl-benzimidazole (32) in 52% yield, together with 1,5-diphenyltetrazole (33) and diphenyl carbodiimide trimer (34). Irradiation of the tetrazole (33) produced only the imidazole (32) but no trimer (34) indicating that the imino nitrene intermediate formed by irradiation of 33 was different from the one produced directly in the primary photolysis of benzophenone diazide (31). No products of a diphenyl-methylene precursor were isolated. 

Oxidation. The reagent oxidizes primary aromatic amines in benzene solution at room temperature to azo compounds (1 -2 days), but yields are variable toluidines, 42, 56, and 6% p-nitroaniline (53%) a-naphthylamine, 3%. Oxidations in acetic... 

Silicon isocyanate reacts exothermally in benzene solution with primary and secondary amines to give the corresponding ureas in yields of 97-100%. Silicon... 

The primary photochemical product formed from the irradiation of the 2-thiones (115) in the presence of alkenes is the oxetanes (116). The reaction conditions use Pyrex filtered light in benzene solution. Under these conditions the initial product is unstable and reacts further either by C-O or C-S bond fission which leads to the isolated products (117) and (118) in the yields shown. 

Probably the most important structural feature of the titanium and other alkoxides is that, although monomeric species can in certain cases exist, especially in very dilute solution, these compounds are in general polymers. Solid Ti(OC2H5)4 is a tetramer, with the structure shown in Fig. 25-A-l. This compact structure neatly allows each Ti atom to attain octahedral coordination. However, in benzene solution, Ti(OR)4 compounds are trimeric for primary alkoxides10 but are unassociated when made from secondary and tertiary alcohols.11 The alkoxides are often referred to as alkyl titanates and under this name are used in heat-resisting paints, where eventual hydrolysis to TiOz occurs. 

Kabaskalian and Townley (1962a) also showed that the primary process gave RO + NO in a series of alkyl nitrites photolyzed in benzene solution. They deduced this from the products formed which were aldehydes and alcohols, the products expected om the disproportionation of RO radicals. For RO radicals... 

An alternative procedure for reductive decarboxylation without the use of trialkyltin hydrides as hydrogen atom donors has been developed Alkane carboxylic acid esters derived from AT-hydroxypyridine-2-thione decomposed to alkyl radical, which can readily accept a hydrogen atom from t-BuSH (equation 74) to give alkanes. This reaction can be conveniently performed as a one-pot experiment wherein the acid chloride of an alkane carboxylic acid, the sodium salt of thiohydroxamic acid, t-BuSH and 4-dimethyl-aminopyridine (DMAP) in benzene solution are heated to reflux. This procedure works well for COOH groups attached to primary and secondary carbon atoms. Instead of AT-hydroxypyridine-2-thione, one can use other thiohydroxamic acids, viz. iV-hydroxy-AT-methylthiobenzamide, 3-hydroxy-4-methylthiazole-2(3if)-thione (equation 75) and l-iV-hydroxy-3-AT-methylbenzoylenethiourea for decarboxylation reactions. 

The highly nucleophilic ylide anion of sodium [cyano(triphenylphosphor-anylidene)methanide] 3, which is available by deprotonation of cyano-methylene triphenylphosphorane with sodium silazanide in benzene solution at room temperature [74], attacks oxiranes by ring-opening. Depending on the work-up conditions and the further reactions employed, y-hydroxynitriles, y-butyrolactones or a-methyleno-y-butyrolactones were obtained from the primary products thus formed (Scheme 27) [16]. For in-... 

Amines. Benzene solutions o-f Fe3nitro group oi nitroaryls to a primary amine in the presence of functional groups without methanol no amine is obtained [63]. No azo, azoxy, or CO insertion products are formed. 

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