5,6-dihydroxyindole-2-carboxylic acid by treatment of sepiomelanin with sodium borohydride.

Mild treatment of sepiomelanin and biosynthetic eumelanins with NaBH₄ in 0.1 N NaOH leads to the isolation of 5,6-dihydroxyindole-2-carboxylic acid ($\text{3}$), a component of structural interest which may account for most of the degradation products of melanins so far obtained.     

Flow injection system with gas diffusion for the sequential determination of total nitrogen and phosphorus in vegetables

 A flow injection system was developed for the sequential determination of total nitrogen and phosphorus in digests of vegetables using potentiometric and spectrophotometric detection systems, respectively. A tubular ammonium selective electrode with a sensor system composed of nonactin/monactin in tris(2-ethylhexyl) phosphate was used. The selectivity limitations of this electrode were overcome by the inclusion of a gas-diffusion unit in the system that separated ammonium from the rest of the sample matrix and allowed the determination of total nitrogen and phosphorus by the partition of the sample plug between two streams. The results obtained with the developed FIA system were in good agreement with those of the reference methods. Sampling rates from 40 to 60 samples per hour and relative standard deviations below 3.5% were achieved. Received: 17 October 1996/Revised: 21 November 1996/Accepted: 27 November 1996     

一种CO2的矿化封存新方法

针对目前CO2矿化封存的研究现状,提出了一种新的CO2矿化封存方法:利用CO2和NH3反应生成三聚氰酸固体,并考察了温度、压力、反应物配比及有无催化剂对三聚氰酸收率的影响。当反应条件为在250℃,22MPa,NH3与CO2反应配比为1∶1.4,反应8h时,最高收率可达到68.3%。此项技术能够与现在工业成熟的富氧燃烧技术联用,实现对CO2的永久性封存,具有经济效益。     

The use of iron carbonyls in the C—C bond formation reactions

Russian Chemical Bulletin - The review systematizes material by key types of reactions promoted by iron carbonyls. The reaction types are subdivided into several principal directions, focusing...     

DERIVATIVES OF 4-CHLORO-3,5-DINITROBENZOTRIFLUORIDE V. SYNTHESIS OF 4,6-DINITRO-2,8-BIS(TRIFLUOROMETHYL) PHENOTHIAZINE (1), ISOPROPYL 2,6-DINITRO-4-TRIFLUOROMETHYLPHENYL SULFIDE (2) AND BIS(2,6-DINITRO-4-TRIFLUOROMETHYLPHENYL) DISULFIDE (3)

Abstract

The reaction of potassium isopropyl dithiocarbonate with 4-chloro-3,5-dinitrobenzotrifluoride in dimethylformamide at 25–30°C afforded the titled phenothiazine (1) and sulfide (2). The reaction of bis(2,6-dinitro-4-trifluoromethylphenyl)-sulfide or the above halogen compound with sodium hydrosulfide in the same solvent at 80–90°C furnished 1. At 25–30°C the latter reaction afforded the titled disulfide (3). Possible mechanisms and supporting nmr, ir and mass spectral data are discussed.     

Copolymerization of Vinyl Chloride and Sulfur Dioxide. II. Copolymerization Rates and Copolymer Compositions

The rate of copolymerization of vinyl chloride (VC) with sulfur dioxide and the composition of the poly (vinyl chloride sulfone) formed have been measured for comonomer liquid mixtures with X_VC = 0.1 to 1.0 and over the temperature range -95 to +46°C.

Polymerization was initiated by γ-irradiation (-95 to +46°C) and with the t-butyl hydroperoxide/SO₂/methanol redox system (-95 to -18°C). The copolymerization rates and copolymer compositions indicated two distinct temperature regions, with a change in mechanism around 0°C. For radiation initiation below 0°C, the rate versus comonomer composition relationship showed a maximum at an x_VC value which increased with increasing temperature. Above 0°C, the rate decreased with increasing temperature and was greatly retarded by SO₂. No high molecular weight copolymer or VC homopolymer was formed on irradiation of comonomer mixtures above ～55°C.     

ON A NEW CLASS OF ANALYTIC FUNCTION DERIVED BY A FRACTIONAL DIFFERENTIAL OPERATOR

Making use of the fractional differential operator, we impose and study a new class of analytic functions in the unit disk （type fractional differential equation）. The main object of this paper is to investigate inclusion relations, coefficient bound for this class. Moreover, we discuss some geometric properties of the fractional differential operator.