2-Styryl-4H-1,3-benzoxazin-4-onium salts

A method was developed for the synthesis of 2-styryl-4H-1,3-benzoxazin-4-onium salts by condensation of 2-alkylbenzoxazinonium salts with aromatic aldehydes. It is shown that these same compounds are formed by acid condensation of salicylamides, salicylnitrile, or salicylaldoxime with aromatic aldehydes in acetic anhydride. The hydrolysis and alcoholysis of the synthesized salts were studied.     

Method for the synthesis of bisbenzo[c]pyrylium salts

A new method for the synthesis of bisbenzo[c]pyrylium salts was developed. The new method is based on the acylation of 1,4-bis(3,4-dimethoxyphenylacetyl)benzene with carboxylic acid anhydrides in the presence of perchloric acid or with carboxylic acids in polyphosphoric acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 600–602, May, 1987.     

Comparative substoichiometric extraction of silver with potassium salts of ethyl,propyl, butyl,pentyl and benzyl xanthates

A rapid and sensitive substoichiometric radiochemical method has been developed for the comparative extraction and quantification of silver with potassium salts of ethyl, propyl, butyl, pentyl and benzyl xanthates from hydrochloric, nitric and sulfuric acid media into chloroform. The effect of 0.1–4M H⁺ ion concentration of the respective acid on the substoichiometric extraction of silver was critically studied. The efficiency of the method developed was tested by the determination of 10–100 μg silver in standard solutions with an average percentage of error better than 2. The methods developed have been utilized to determine silver content in photofilm washing collected from various photostudios in Tirupati, India.     

Bisacylation of the anhydride and esters of 4-methyl-1,2,3,4-tetrahydrophthalic acid

The bisacylation of the anhydride and esters of 4-methyl-1,2,3,4-tetrahydrophthalic acid by anhydrides of carboxylic acids in the presence of perchloric acid results in the formation of derivatives of 1,3-dialkyl-6, 7-dicarboxy-5,6,7,8-tetrahydro-2-benzopyrylium salts. Some reactions of the salts obtained, including their recyclization under the action of nucleophiles, have been studied. A convenient preparative method for the synthesis of 6,7-dicarboalkoxy-5,6,7,8-tetrahydroixoquinolines has been developed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1318–1321, October, 1984.     

Cyclic hydroxamic acids of the indole series

A convenient method was developed for obtaining 2-N-hydroxy-3-keto-1-phenyl-1,3-dihydropyrrolo[3,4-b]indoles by reaction of indole-2-hydroxamic acid with substituted benzaldehydes. Complex compounds of trivalent iron salts with cyclic hydroxamic acids were isolated.Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 227–229, February, 1985.     

Highly selective method for the synthesis of substituted alkylpyridines

Conclusions A highly selective method was developed for the synthesis of substituted alkylpyridines by the reactions of ethynylcarbinols and vinylacetylenes with carboxylic acid chlorides and ammonia in the presence of zinc chloride. The intermediate formation of pyrylium salts was demonstrated.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2600–2604, November, 1988.     

Microwave-assisted synthesis of α-aminophosphinic acids from hypophosphorus acid salts under solvent free conditions

A simple, efficient, and general method has been developed for the synthesis of α-aminophosphinic acids from hypophosphorus salts under solvent-free conditions using microwave irradiation. α-Aminophosphinic acids were obtained in high yield under mild conditions by reaction of the amine salts of hypophosphorus acid with aldehydes in the presence of microwave irradiation.     

Thermochemistry of complex salts of transition metal perchlorates with tetrazole ligands

The combined use of combustion and solution calorimetry was proposed as a method for determining the standard enthalpy of formation of the complex salts of transition metals, viz., cobalt(II), nickel(II), and zinc, with the organic ligand (5-aminotetrazol-1-yl)acethydrazide. The enthalpies of solution in water and in a 0.1 M solution of hydrochloric acid were measured for the complex salts and ligand. The enthalpy of combustion of the ligand was determined by the combustion calorimetry method, and its standard enthalpy of formation was calculated. The thermochemical cycle was developed for determining the standard enthalpy of formation of the complex salts. The reliable values of the enthalpies of formation of the salts in the standard states were obtained, and the enthalpies of formation of the earlier unknown complex ions were determined.     

Synthesis and Structure of 1-tert-Butyl-3-R-tetrazolium Salts

An effective method was developed for the synthesis of 1,3-disubstituted tetrazolium salts by the quaternization of 2-monosubstituted tetrazoles, including functionally substituted compounds, with tert-butanol in 72% perchloric acid. An X-ray diffraction investigation of examples of this series of salts - 1-tert-butyl-3-(1-methylvinyl)- and 1,3-di-tert-butyltetrazolium perchlorates - was carried out.     

Three-component condensation of 5-aminoimidazole derivatives with aldehydes and Meldrum’s acid. Synthesis of 3,4,6,7-tetrahydroimidazo[4,5-b]pyridin-5-ones

A convenient method for the synthesis of the earlier unknown substituted 3,4,6,7-tetrahydroimidazo[4,5-b]pyridin-5-ones was developed based on a three-component condensation of 5-aminoimidazole derivatives, aldehydes, and Meldrum’s acid. Unstable aminoimidazole derivatives were readily formed in situ by decarboxylation of 5-amino-4-imidazolecarboxylic acids in acidic medium at room temperature, whose sodium salts were obtained by the alkaline hydrolysis of the corresponding, readily available esters.     

Synthesis of zwitterionic salts via three component reactions of nitrogen-containing heterocycles, acetylenedicarboxylate and cyclic 1,3-dicarbonyl compounds

A practical synthetic procedure for the preparation of the charge-separated pyridinium-Meldrum acid zwitterionic salts was developed through a unique one-pot three component reaction of pyridine, acetylenedicarboxylate and Meldrum acid. Other nitrogen-containing heterocycles such as N-methylimidazole, 2-picoline, quinoline, isoquinoline and other cyclic 1,3-dicarbonyl compounds such as 1,3-cyclopentanedione, 1,3-cyclohexanedione, barbituric acid also took part in the reaction to give corresponding zwitterionic salts in moderate yields, respectively. In one case an unusual isoquinolinium 1,3-cyclopentanedionate was obtained. A feasible explanation is given for this novel one-pot tandem reaction and the formation of different kinds of products.     

2-Benzopyrylium salts

-Veratrylindanones were obtained by reaction of -veratrylcinnamic acid with veratrole in polyphosphoric acid (PPA). A method for the synthesis of indeno-2-benzopyrylium salts based on acylation of the indanones with the free acids and their anhydrides was developed. It was shown that indeno-2-benzopyrylium salts can be converted to the little-studied indeno[1,2-c]isoquinoline bases.See [1] for communication XIV.Translated from Khimiya Geterotsiklicheskii Soedinenii, No. 2, pp. 181–183, February, 1974.     

Synthesis of o-Carboranyl Containing Esters of Pentavalent Phosphorus Acids

Abstract

A new method for the synthesis of o-carboranyl containing phosphoric, phosphonic and phosphinic acid esters, where the o-carboranil group is in the ester group, has been developed. The propargyl esters of these acids were prapared in two ways: by the reaction of phosphorus acid salts with propargyl chlorid and by interaction of propargyl alcohol with acid chlorides in the presence of Et₃N. The propargyl esters have been converted into carboranyl containing compounds upon treatment with decaborane and dimethyl aniline     

Three-component condensation of 3-aminothiophene-2-carboxylic acid derivatives with aldehydes and Meldrum’s acid

A convenient method was developed for the synthesis of the previously unknown substituted 6,7-dihydro-4H-thieno[3,2-b]pyridin-5-ones based on the three-component condensation of 3-aminothiophenes, Meldrum’s acid, and aromatic aldehydes. 3-Aminothiophenes are easily formed in situ by decarboxylation of 3-aminothiophene-2-carboxylic acids in an acidic medium. Sodium salts of the latter acids were prepared by alkaline hydrolysis of the corresponding available esters.     

Studies on quinoline derivatives and related compounds. 1. A new synthesis of 1-alkyl-1,4-dihydro-4-oxo-3-quinolinecarboxylic acids

A novel preparative method for 1-alkyl-1,4-dihydro-4-oxo-3-quinolinecarboxylic acids was developed. The key process is the cyclization of N-alkylanilinomethylenemalonales, which was effected successfully in the presence of polyphosphoric acid, polyphosphate ester, boron tri-fluoride or a mixture of acetic anhydride and sulfuric acid. With phosphorus oxychloride, N-alkylanilinomethylenemalonates yielded 1-alkyl-4-chloro-3-carbethoxyquinolinium salts which were hydrolyzed readily to ethyl 1-alkyl-1,4-dihydro-4-oxo-3-quinolineearboxylates or their acids. By means of this novel method several new 1-alkyl-1,4-dihydro-4-oxo-3-quinolineearboxylic acids were prepared.     

Acidimetric determination of sodium salts of methyl sulfamic acid

A procedure for the determination of sodium salts of methyl sulfamic acid as tertiary amines by acidimétrie titration in glacial acetic acid was developed. The total error of the procedure did not exceed 1%. The procedure is simple and can be carried out under ordinary laboratory conditions.     

Micropore to macropore structure-designed silicas with regulated condensation of silicic acid nanoparticles

A new preparation method for porous silica particles was developed using activated silica sols which are called nano-silica solutions in this paper. Several kinds of organic and inorganic acids are employed to neutralize diluted sodium silicate solutions to form the nano-silica solutions: formic acid, acetic acid, propionic acid, oxalic acid, succinic acid, dl-malic acid, citric acid, and tricarballylic acid as carboxylic acids, and sulfuric acid and hydrochloric acid as inorganic acids. The effect of salts in the nano-silica solution is also studied. The products were investigated using a field emission scanning electron microscope, an X-ray diffractometer, the nitrogen adsorption technique, and a mercury porosimeter. Microporous silicas were produced when carboxylic acids were applied; the formation of micropores was influenced by the pH of the nano-silica solutions and molecular sizes of the carboxylic acids. Addition of a salt in a citric acid solution increased the mesopore volume. Macropores were formed when inorganic acids including salts were applied; the salt nanoparticles which were crystallized in silica spheres acted as templates. The anion types and salt concentrations in the nano-silica solutions affected the aggregation condition of silica nanoparticles, following the Schulze-Hardy rule.     

Comparative substoichiometric extraction of silver with potassium salts of ethyl, propyl, butyl, pentyl and benzyl xanthates

A rapid and sensitive substoichiometric radiochemical method has been developed for the comparative extraction and quantification of silver with potassium salts of ethyl, propyl, butyl, pentyl and benzyl xanthates from hydrochloric, nitric and sulfuric acid media into chloroform. The effect of 0.1–4M H⁺ ion concentration of the respective acid on the substoichiometric extraction of silver was critically studied. The efficiency of the method developed was tested by the determination of 10–100 g silver in standard solutions with an average percentage of error better than 2. The methods developed have been utilized to determine silver content in photofilm washing collected from various photostudios in Tirupati, India.     

Colorimetric determination of low pH with Malachite Green

A spectrophotometric method was developed for determination of concentration-based pH values from 0 to 2 with Malachite Green indicator. A quadratic model equation was based on the ratio of the absorbances of the peak at 618 nm and the isosbestic point at 518 nm. Normalization to the isosbestic point was used to stabilize the response because the color faded; the useful time interval was within 5 min after indicator addition. Model and verification sets agreed within +/-0.02 pH units between pH 0.3 and 1.8. This excellent precision makes the colorimetric method useful for acid determinations with a relative precision of > +/-5%. The presence of salts at a salt/acid equivalent ratio >0.1 caused a low pH bias.     

A new method for the construction of pyrylium and pyridine rings fused to derivatives of furan and indole

A simple method is described for the construction of the pyrylium ring fused to furans and indoles, by the acylation of 2-methyl-5-acetonylfuran, 3-acetonylindole and its 1-alkyl derivatives with acid anhydrides in presence of 70% perchloric acid. The previously unknown furano[3, 2-c]-and indolo[2, 3-c]pyrylium salts are prepared. A method for the preparation of 4-methyl-harman and its alkyl homolog has been developed.