Synthesis of 8-Aryl[1,2,4]triazolo[1,5-d][1,2,4]triazin-5(6H)-ones by S HN Reactions

A new procedure has been proposed for the synthesis of 8-aryl[1,2,4]triazolo[1,5-d][1,2,4]-triazin-5(6H)-ones by reaction of 6-aryl-1,2,4-triazin-3(2H)-ones with hydrazides derived from aliphatic, aromatic, and heterocyclic carboxylic acids. The process invloves nucleophilic substitution of hydrogen (S_N ^H)in aryltriazinones, oxidative closure of azole ring, and Dimroth rearrangement.     

Cyclothiomethylation of carboxylic acid hydrazides with aldehydes and H<Subscript>2</Subscript>S

The cyclothiomethylation of carboxylic acid hydrazides RCONHNH₂ (R = C₅H₄N, Ph, 2-MeOC₆H₄, or 4-HOC₆H₄CH₂) with formaldehyde and H₂S at 70 °C affords predominantly the corresponding N-(1,3,5-dithiazinan-5-yl)amides, whereas this reaction at 0–−50 °C gives a mixture of the latter compounds with 3-acyl-1,3,4-thiadiazolidines. N-(1,3,5-Dithiazinan-5-yl)-amides were selectively synthesized by the reaction of carboxylic acid hydrazides with formaldehyde and H₂S in the presence of BuONa in BuOH.     

Reaction of carboxylic acids with tetrachlorosilane

Tetrachlorosilane reacted with carboxylic acids RCOOH (R = Me, Bu, t-Bu) to give the corresponding acid chlorides RCOCl in 75–95% yield. The reactions of SiCl₄ with trichloroacetic and 2-fluorobenzoic acids (R = Cl₃C, 2-FC₆H₄) occurred more difficultly, presumably for steric reasons, and the yields of the corresponding acid chlorides were 11 and 22%, respectively. Tetrachlorosilane failed to react with stearic acid under analogous conditions. Products of the reactions of SiCl₄ with chloroacetic and benzoic acids RCOOH (R = ClCH₂, Ph) were tetraacyloxysilanes Si(OCOR)₄, and tetrakis(chloroacetoxy)silane was formed in almost quantitative yield. The reaction of SiCl₄ with glutaric acid led to the formation of a rubber-like polymeric material with the composition C₅H₆Cl₂O₄Si. The effect of pKa values of carboxylic acids on the direction and mechanism of the examined reaction is discussed.     

Reaction of 1-germatranol hydrate with carboxylic acids

Reaction of 1-germatranol hydrate with carboxylic acids RCOOH (R = ClCH₂, PhCH=CH, Ph, 2-FC₆H₄, 3-BrC₆H₄, 3-HOC₆H₄, 3-EtOC₆H₄) in protic (CH₃OH, iso-C₅H₁₁OH) and aprotic polar solvent (CH₃CN) is studied. 1-Acyloxygermatranes RC(O)OGe(OCH{in2}CH{in2}){in3}N are formed in yields from 11 to ~100 % depending on the nature of the acid, solvent, duration of the process and the method of its completion. The reaction is the most effective in acetonitrile. Its topochemical completion (heating of the reaction residue in a vacuum) increases the yield of 1-acyloxygermatranes.     

Synthesis and ring transformations of 1-amino-1,2,3,9a-tetrahydroimidazo[1,2-a]indol-2(9H)-ones

Heating 1-carbamoylmethyl-2,3,3-trimethyl-3H-indolinium chloride in the presence of hydrazine bishydrate produces regioselectively the five-membered heterocycle 1-amino-1,2,3,9a-tetrahydro-9,9,9a-trimethylimidazo[1,2-a]indol-2(9H)-one. The assignment of the structure is based on extensive ¹H, ¹³C and ¹⁵N NMR spectroscopic studies. No ring-chain tautomerism of the 1-amino-1,2,3,9a-tetrahydroimidazo[1,2-a]indol-2(9H)-one was observed to open-chain hydrazides or the corresponding six-membered 1,2,10,10a-tetrahydro[1,2,4]triazino[4,3-a]indol-3(4H)-one. Further transformations of 1-amino-1,2,3,9a-tetrahydroimidazo[1,2-a]indol-2(9H)-one were performed by treatment with aromatic aldehydes, acid chlorides and isocyanates giving access to 40 novel hydrazones, N,N′-diacylhydrazines, N-acyl-N′-carbamoylhydrazines and 1,3,4-oxadiazoles.     

Selective Esterification of Aliphatic Carboxylic Acids in the Presence of Aromatic Carboxylic Acids Over Monoammonium Salt of 12‐Tungstophosphoric Acid

Monoammonium salt of 12‐tungstophosphoric acid [(NH₄)H₂PW₁₂O₄₀] was found to be a practical and useful heterogeneous catalyst for an efficient and selective esterification of aliphatic carboxylic acids with alcohols in the presence of aromatic carboxylic acids. The heteropoly acid–based heterogeneous catalyst has the advantages of a simple workup procedure, water insolubility, and good activity.     

Catalytic thiomethylation of carboxylic acid hydrazides

Thiomethylation of carboxylic acid hydrazides with dimethylaminomethyl sulfides RSCH₂NMe₂ yielded the corresponding N′,N′-bis(sulfanylmethyl)carbohydrazides. When bis-sulfides Me₂NCH₂S(CH₂) _n SCH₂NMe₂ (n = 2–4) are used for thiomethylation, N-(acylamino)-substituted 1,5-dithia-3-azacycloalkanes are formed. These compounds can also be synthesized by CuCl₂·2H₂O-catalyzed thiomethylation of carboxylic acid hydrazides with either CH₂O and thiols or α,ω-alkanedithiols.     

Synthesis,characterization and alcohol oxidation properties of multi-wall carbon nanotubes functionalized with a cobalt(II) Schiff base complex

A hydroxyl functionalized cobalt(II) Schiff base complex has been covalently anchored to modified multi wall carbon nanotubes (MWNTs). The modified MWNTs have been characterized by physico-chemical and spectroscopic methods. The results suggest that the symmetrical Schiff base, N,N′-bis(4-hydroxysalicylidene)-ethylene-1,2-diamine; H₂[((OH)₂-salen)] acts as a tetradentate N₂O₂ donor via the deprotonated phenolic oxygens and azomethine nitrogens. The functionalized [Co((OH)₂-salen)]–MWNTs catalyze the oxidation of aliphatic and aromatic alcohols into the corresponding carboxylic acids and ketones in the presence of 30% H₂O₂ in good yields. The system is truly heterogeneous (no leaching observed) and reusable (no decrease in activity over three consecutive runs).     

A simple and efficient method of preparing α-bromo carboxylic acids

A new and convenient method for α-bromination of aliphatic carboxylic acids is reported. Heating carboxylic acids for 16 hours at 85 °C in trifluoroacetic acid with 1.5 equivalents of N-bromosuccinimide and a catalytic amount of concentrated H₂SO₄ leads to good yields of the respective α-bromocarboxylic acids.     

Shock tube and modeling study of 1,3-butadiene pyrolysis

1,3-Butadiene (1,3-C₄H₆) was heated behind reflected shock waves over the temperature range of 1200–1700 K and the total density range of 1.3 × 10⁻⁵ −2.9 × 10⁻⁵ mol/cm³. Reaction products were analyzed by gas-chromatography. The concentration change of 1,3-butadiene was followed by UV kinetic absorption spectroscopy at 230 nm and by quadrupole mass spectrometry. The major products were C₂H₂, C₂H_4, C₄H₄, and CH₄. The yield of CH₄ for a 0.5% 1,3-C₄H₆ in Ar mixture was more than 10% of the initial 1.3-C₄H₆ concentration above 1500 K. In order to interpret the formation of CH₄ successfully, it was necessary to include the isomerization of 1,3-C₄H₆ to 1,2-butadiene (1,2-C₄H₆) and to include subsequent decomposition of the 1,2-C₄H₆ to C₃H₃ and CH₃. The present data and other shock tube data reported over a wide pressure range were qualitatively modeled with a 89 reaction mechanism, which included the isomerizations of 1,3-C₄H₆ to 1,2-C₄H₆ and 2-butyne (2-C₄H₆). © 1996 John Wiley & Sons, Inc.     

Reactions of N"-acyl- and N"-tosyl-substituted hydrazides of 2-aminobenzoic acid with carbonyl compounds

The reactions of N"-acyl and N"-tosyl-substituted hydrazides of 2-aminobenzoic acid with aliphatic, aromatic, and heterocyclic aldehydes or aliphatic ketones afforded 3-acyl- and 3-tosylamido-1,2-dihydroquinazolin-4-one derivatives, respectively. The structures of the reaction products were established by NMR spectroscopy and X-ray diffraction analysis.     

Extraction of copper(II) with 1,2-diacylhydrazines in the presence of associated metals

Conditions of Cu(II), Zn(II), Ni(II), Co(II), and Fe(III) ions extraction (pH values, effect of reagent amount) with symmetrical 1,2-diacylhydrazines derived from straight-chain aliphatic carboxylic acids and α-branched higher carboxylic acids Versatic-10 were studied. The separation coefficients of element pairs and pH of half extraction were calculated. The values of [Cu(II)]: [reagent] ratios in extracted complexes were determined. 1,2-Diacylhydrazines were shown to be more selective extractants toward nonferrous metal ions as compared with carboxylic acids, while the branching and elongation of alkyl chain in the reagents enhances their extraction properties and compatibility with hydrocarbon solvents.     

Reaction of Long-Chain Vanillyl Esters with CH-Acids and 2-Naphthylamine

The previously unknown 4-(alkyl-11-oxo-7,8,9,10,11,12-hexahydrobenzo[a]acridin-12-yl)- and 4-(alkyl-1,8-dioxo-2,3,4,5,6,7,8,9-octahydro-1H-xanthen-9-yl)-2-methoxyphenyl esters of aliphatic (C₅-C₇, C₁₂) carboxylic acids were synthesized via cascade heterocyclization of cyclohexane-1,3-dione and dimedone with 2-naphthylamine and long-chain vanillyl esters.     

Synthesis of some new mono- and di-substituted o-carborane derivatives with thiolate and carbamate moieties: crystal structure of 1-(SNC5H4)-1,2-C2B10H11

Some new o-carborane derivatives of stoichiometry 1,2-(SR)₂-1,2-C₂B₁₀H₁₀ [SR=S₂NC₇H₄, S₂CNEt₂] have been synthesised by reaction of 1,2-Li₂-1,2-C₂B₁₀H₁₀ with the corresponding disulfide derivatives RSSR (RSSR=(C₇H₄NS₂)₂, 2,2′-dithiobis(benzothiazole); (Et₂NCS₂)₂, tetraethylthiuram disulfide) in molar ratio 1:2. The reaction of 1-Li-2-Si^tBuMe₂-1,2-C₂B₁₀H₁₀ with RSSR (RSSR=(C₅H₄NS)₂, 2,2′-dithiodipyridine; (C₇H₄NS₂)₂) in molar ratio 1:1 has afforded the new mixed di-substituted compounds 1-SR-2-Si^tBuMe₂-1,2-C₂B₁₀H₁₀ (SR=SNC₅H₄; S₂NC₇H₄). The reaction of 1-SNC₅H₄-2-Si^tBuMe₂-1,2-C₂B₁₀H₁₀ with NBu₄F in THF in molar ratio 1:2 has afforded the mono-substituted derivative 1-SNC₅H₄-1,2-C₂B₁₀H₁₁, whereas the treatment of 1,2-(C₇H₄NS₂)₂-1,2-C₂B₁₀H₁₀ with NBu₄F in THF in molar ratio 1:5 has led to the partially degraded derivative NBu₄[7,8-(S₂NC₇H₄)₂-7,8-C₂B₉H₁₀]. The crystal structure of 1-SNC₅H₄-1,2-C₂B₁₀H₁₁ has been determined by X-ray diffraction.     

Physicochemical properties of 1,2-diacylhydrazines based on α-branched tertiary carboxylic acids Versatic

New 1,2-diacylhydrazines based on higher α-branched tertiary carboxylic acids Versatic-10 were prepared. Taking into consideration the possible application of these reagents in the processes of heterophase separation of nonferrous metal ions the physicochemical properties of the reagents were examined: the solubility, the stability against hydrolysis, thermal stability. The values of the constants of acid dissociation pK _a1 and pK _a2 and the protonation constant pK _prot were determined.     

Synthesis of New Pyrimido[4′,5′:3,4]pyrazolo[1,2‐b]phthalazine‐4,7,12‐triones: Derivatives of a New Heterocyclic Ring System

Several derivatives of the new pyrimido[4′,5′:3,4]pyrazolo[1,2‐b]phthalazine‐4,7,12‐trione ring system have been prepared by the reaction of 3‐amino‐1‐aryl‐5,10‐dioxo‐5,10‐dihydro‐1H‐pyrazolo[1,2‐b]phthalazine‐2‐carbonitriles with aliphatic carboxylic acids in the presence of phosphoryl chloride (POCl₃). The synthesized compounds were characterized on the basis of IR, ¹H NMR, and ¹³C NMR spectral and microanalytical data.     

Physicochemical Properties of 1,2-Diacylhydrazines Derived from Aliphatic Carboxylic Acids

The solubility and resistance to oxidation and hydrolysis of 1,2-diacylhydrazines derived from acetic, propionic, butyric, and valeric acids were studied in view of possible application of these compounds for concentrating nonferrous metals. The pK ₁ and pK ₂ values of the 1,2-diacylhydrazines were determined. The stability of conformers and the electron density distribution in the coordination-active moiety were estimated by SCF MO LCAO semiempirical calculations in the MNDO-PM3 approximation.     

Oxyethyl hydrazides as potential flotation agents

Physicochemical (acid-base, solubility, stability against oxidation and hydrolysis) and surface-active (wetting angles, surface tension, foaming) properties of N′-oxyethyl hydrazides of aliphatic carboxylic acids were studied. The data obtained are analyzed in terms of the main requirements imposed on flotation agents.     

Preparation of 1,1′-Oxy-bis(3,3-bis(trifluoromethyl)-3(1H)-1,2-benziodoxole) and 2-(N-(p-Toluenesulfonyl)imino)iodobenzylmethyl Ether

Conditions for improved preparation of the crystalline iodine(III) reagents [1,2-C₆H₄(C(CF₃)₂OI)]₂O and 1,2-C₆H₄(CH₂OMe)(I=NTs) are presented together with their x-ray structures. The former is prepared by hydrolysis of 1,2-C₆H₄(C(CF₃)₂OICl (x-ray) and allows the preparation of cyclic sulfates from alkenes; the latter fashions sulfamidate under related conditions.     

Chlorine-photosensitized oxidations of chloroethanes and chloroethylenes in the gas phase

Long-chain chlorine-photosensitized oxidation has been observed in the gas phase at about 355°K for 1,1,2,2- and 1,1,1,2-C₂H₂Cl₄, C₂HCl₅, and C₂Cl₄ but not for C₂H₆, 1,2-C₂H₄Cl₂, 1,1,1-C₂H₃Cl₃, C₂H₄, and 1,2-C₂H₂Cl₂. This is shown to depend on the exothermicity of the dissociation of the chloroethoxy radicals which must be involved in each reaction system.