Formic acid reduction—XVII : Kinetic studies on the formic acid reduction of N-benzylideneaniline

The formic acid reduction of azomethine which has been reported² to proceed nearly quantitatively by the use of the formate reagent, 5HCO₂H·2NEt₃, was kinetically investigated by the carbon dioxide trapping and UV spectroscopic methods, using N-benzylideneaniline as a representative. Rate data gave the rate equation, v = (k + k′ [NEt₃])[N-benzylideneaniline][HCO₂H], indicating two-path mechanism. By the technique of using deuterated formic acids, it was found that the hydrogen bound to the carbon of formic acid is transferred as hydride to the carbon of the CN double bond in the rate determining step. The reaction is facilitated by the electron-releasing substituents of the two benzene rings of N-benzylideneaniline. On the bases of these results a possible mechanism is proposed.     

Crystal structures of inclusion complexes of cholic acid with aniline,mono- and difluorinated anilines: Guest information expressed by molecular assembly

The crystal structures of cholic acid (CA), a naturally occurring bile acid, complexed with aniline, and its mono- and difluorinated derivatives were elucidated by X-ray crystallography. Comparison of the structures obtained shows that the molecular assembly pattern and the related structural change of the CA molecule vary among different complexes. These structural changes are the molecular information of the guests. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82197 (27 pages).     

Preparation and application of porous calcium fluoride—a novel fluorinating reagent and support of catalyst

A novel material, porous calcium fluoride (PCF) with more than 60 m²/g surface area, was prepared by the reaction of soda lime (SL) with anhydrous hydrogen fluoride (AHF), and its application as a fluorinating reagent and support of catalyst was investigated.     

Kinetics and mechanism of (CF3)2CHOCH3 reaction with OH radicals in an environmental reaction chamber

The atmospheric chemistry of (CF3)2CHOCH3, a possible HCFC/HFC alternative, was studied using a smog chamber/FT-IR technique. OH radicals were prepared by the photolysis of ozone in a 200-Torr H2O/O3/O2 gas mixture held in an 11.5-dm3 temperature-controlled chamber. The rate constant, k1, for the reaction of (CF3)2CHOCH3 with OH radicals was determined to be (1.40 +/- 0.28) x 10(-12) exp[(-550 +/- 60)/T] cm3 molecule(-1) s(-1) by means of a relative rate method at 253-328 K. The value of k1 at 298 K was (2.25 +/- 0.04) x 10(-13) cm3 molecule(-1) s(-1). The random errors are reported with +/-2 standard deviations, and potential systematic errors of 15% could increase k(1). In considering OH-radical reactions, we estimated the tropospheric lifetime of (CF3)2CHOCH3 to be 2.0 months using the rate constant at 288 K. The degradation mechanism of (CF3)2CHOCH3 initiated by OH radicals was also investigated using FT-IR spectroscopy at 298 K. Products (CF3)2CHOC(O)H, CF3C(OH)2CF3, CF3C(O)OCH3, and COF(2) were identified and quantified. The branching ratio, k1a/k1b, was estimated to be 2.1:1 for reactions (CF3)2CHOCH3 + OH --> (CF3)2CHOCH2*+ H2O (k1a) and (CF3)2CHOCH3 + OH --> (CF3)2C*OCH3 + H2O (k1b).     

Synthesis and properties of 3-arylcyclohepta[4,5]imidazo[1,2-a]-1,3,5-triazine-2,4(3H)-diones and related compounds: photo-induced autorecycling oxidation of some amines

Novel 3-phenyl- and 3-(4-nitrophenyl)cyclohepta[4,5]imidazo[1,2-a]-1,3,5-triazine-2,4(3H)-diones and the corresponding imino derivatives 5a,b and 6a,b were synthesized in modest to moderate yields by the abnormal and normal aza-Wittig reaction of 2-(1,3-diazaazulen-2-ylimino)triphenylphosphorane with aryl isocyanates and subsequent heterocyclization reaction with a second isocyanate. The related cationic compound, 1-methyl-3-phenylcyclohepta[4,5]imidazo[1,2-a]-1,3,5-triazine-2,4(3H)-dionylium tetrafluoroborate 7a, was also prepared. The electrochemical reduction of these compounds exhibited more positive reduction potentials as compared with those of the related compounds of 3,10-disubstituted cyclohepta[4,5]pyrrolo[2,3-d]pyrimidine-2,4(1H,3H)-dione systems. In a search of the oxidizing ability, compounds 5a, 6a, and 7a were demonstrated to oxidize some amines to give the corresponding imines in more than 100% yield under aerobic and photo-irradiation conditions, while even benzylamine was not oxidized under aerobic and thermal conditions at 100 °C. The oxidation reactions by cation 7a are more efficient than that by 5a and 6a. Quenching of the fluorescence of 5a was observed, and thus, the oxidation reaction by 5a probably proceeds via electron-transfer from amine to the excited singlet state of 5a. In the case of cation 7a, the oxidation reaction is proposed to proceed via formation of an amine-adduct of 7a and subsequent photo-induced radical cleavage reaction.     

Enantioselective borohydride reduction catalyzed by optically active cobalt complexes

The highly enantioselective borohydride reduction of aromatic ketones or imines to the corresponding alcohols was developed in the presence of a catalytic amount of an optically active cobalt(II) complex catalyst. This enantioselective reduction is carried out using a precisely premodified borohydride with alcohols such as tetrahydrofurfuryl alcohol, ethanol and methanol. High optical yields are obtained by choosing the appropriate alcohol as modifiers and a suitable beta-ketoiminato ligand of the catalyst. The enantioselective borohydride reduction has been successfully applied to the preparation of optically active 1,3-diols, the stereoselective reduction of diacylferrocenes, and dynamic and/or kinetic resolution of 1,3-dicarbonyl compounds.     

Kinetics study of the gas-phase reactions of C2F5OC(O)H and n-C3F7OC(O)H with OH radicals at 253–328 K

The rate constants, k₁ and k₂ for the reactions of C₂F₅OC(O)H and n-C₃F₇OC(O)H with OH radicals were measured using an FT-IR technique at 253–328 K. k₁ and k₂ were determined as (9.24 ± 1.33) × 10⁻¹³ exp[−(1230 ± 40)/T] and (1.41 ± 0.26) × 10⁻¹² exp[−(1260 ± 50)/T] cm³ molecule⁻¹ s⁻¹. The random errors reported are ±2 σ, and potential systematic errors of 10% could add to the k₁ and k₂. The atmospheric lifetimes of C₂F₅OC(O)H and n-C₃F₇OC(O)H with respect to reaction with OH radicals were estimated at 3.6 and 2.6 years, respectively.     

The synthesis of benzophenothiazine derivatives

Summary The reaction of substituted 1,4-naphthoquinones with 2-aminothiophenol ando-aminoheterocyclic thiones in acidic condition afforded benzophenothiazin-5-one and azabenzophenothiazin-5-one derivatives, respectively.

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Die Synthese von Benzophenothiazin-Derivaten

Zusammenfassung Die Reaktion von substituierten 1,4-Naphthochinonen mit 2-Aminophenol bzw.o-aminoheterocyclischen Thionen führte unter sauren Bedingungen zu Benzophenothiazin-5-onen bzw. Azabenzophenothiazin-5-onen.