Showing papers on "Color reaction published in 1977"
56 citations
TL;DR: The products of the colour reaction of a systematically selected series of phenols with the MBTH reagent have been investigated by means of spectrophotometric and chromatographic methods.
Abstract: The products of the colour reaction of a systematically selected series of phenols with the MBTH reagent have been investigated by means of spectrophotometric and chromatographic methods. 2,6-Dialkylphenols give red dyes formed by oxidative coupling in thep-position and 2,4-dialkylphenols violet colours due to reaction in theo-position. Phenols with a freep-position and at least one freeo-position give a mixture of the red and violet products. In the case of halogenated phenols dehalogenation occurs in both theo-andp-positions.
22 citations
TL;DR: In this article, the decomposition of Gibbs reagents (2,6-dichloro- and 2, 6-dibromoquinonechloroimines) in solution is shown to occur first under the formation of the quinoneimine (which reacts very rapidly with phenol and is the operative species in the colour reaction) and then products (one of which is the tetrahaloindophenol derivative) which do not react with phenols.
Abstract: The decomposition of the Gibbs reagents (2,6-dichloro- and 2,6-dibromoquinonechloroimines) in solution is shown to occur first under the formation of the quinoneimine (which reacts very rapidly with phenol and is the operative species in the colour reaction) and then products (one of which is the tetrahaloindophenol derivative) which do not react with phenol. The rate decomposition increases with increasing pH. The reagents, when purified by crystallisation fromn-heptane and kept in the dark at room temperature, are stable. Stock 0.01M solutions in ethanol or acetone are stable for at least 6 months if stored in a refrigerator. The optimum pH for the colour reaction with phenols is 8.5. Borate, phosphate or Britton-Robinson buffers are suitable, but not ammonia or glycocoll buffers.
15 citations
15 citations
TL;DR: The colour reaction is sensitive and the absorbance of the extract in 5 ml of xylene obeys Beer's law at saccharin concentrations between 20 and 400 µg ml–1.
Abstract: Saccharin reacts quantitatively with phenothiazine (thiodiphenylamine) and copper(II) acetate dissolved in 50%V/V ethanol at 70 °C. The reaction product can be dissolved in an organic solvent and has a characteristic colour. The colour reaction is sensitive and the absorbance, at 510 nm, of the extract in 5 ml of xylene obeys Beer's law at saccharin concentrations between 20 and 400 µg ml–1. Cyclamates, sorbic acid, benzoic acid, 4-hydroxybenzoic acid and dehydroacetic acid do not interfere. Recoveries of saccharin from soft drinks were satisfactory. A procedure suitable for routine use is proposed.
13 citations
TL;DR: In this article, the determination of alpha-amino nitrogen (AN) is performed via the formation of amino acid copper complexes and subsequent colorimetric estimation of the dissolved copper as copper diethyldithiocarbamate.
Abstract: The determination of alpha-amino nitrogen (alpha-AN) is performed via the formation of amino acid copper complexes and subsequent colorimetric estimation of the dissolved copper as copper diethyldithiocarbamate. The continuous colour reaction by means of an auto-analyzer increases the reliability of the measured values (variation coefficient = 1.7%) compared to the laborious manual method. The stability of the amino acid copper complexes and of copper diethyldithiocarbamate was verified and possible interferences with the colour reaction were discussed. Ammonia does not interfere with the determination of alpha-AN in protein hydrolysates, whereas traces of detergent residues bias the measured values.
7 citations
TL;DR: In this article, the role of ammonium ions is explained as inhibition of the decomposition of 4-dimethylaminoantipyrine to form imino-bis-phenazone.
Abstract: In connection with a systematic investigation of the colour reaction of phenols to form quinoneimine dyes the reaction of phenol with 4-dimethylaminoantipyrine and an oxidizing agent has been studied. Though it has been found that the resulting coloured reaction product is identical with that of the reaction of phenol with 4-aminoantipyrine and an oxidizing agent (Emerson reaction), a different mechanism is operative. The reaction of phenol with 4-dimethylaminoantipyrine seems to proceed through oxidative degradation to 4-aminoantipyrine which reacts with phenol according to the Emerson reaction. In the literature this has been explained as occuring with intermediate formation of a quinoneimine, for which the presence of ammonium ions in the reaction mixture is necessary. In this communication the role of the ammonium ions is explained as inhibition of the decomposition of 4-dimethylaminoantipyrine to form imino-bis-phenazone. Phenol can also react with aminophenazone and an oxidizing agent in the absence of ammonium ions.
5 citations
Patent•
29 Apr 1977
TL;DR: In this article, a reagent for determining the ethyl alcohol content of a gas, particularly human breath, by means of a color reaction was proposed. But this reagent was used in a tube for use in connection with drunken driving.
Abstract: The invention concerns a reagent for determining the ethyl alcohol content of a gas, particularly human breath, by means of a color reaction. This reagent consists of a mixture of iodine pentoxide, a colorless metal nitrate or concentrated nitric acid, and 75-98% sulphuric acid, the original white color of the reagent changing to pink, brown or black depending on the ethyl alcohol content of the gas. In a preferred embodiment of the invention, the reagent is placed in a tube for use in connection with drunken driving.
5 citations
TL;DR: In this article, three isomers of 1 : 2 complex of picric acid and creatinine were isolated in crystalline forms from the alkaline reaction mixture of the acid and excess creatinines, based on the nuclear magnetic resonance (NMR) and high performance liquid chromatography studies.
Abstract: Three isomers of 1 : 2 complex of picric acid and creatinine were isolated in crystalline forms from the alkaline reaction mixture of picric acid and excess creatinine. The structures were discussed on the basis of the nuclear magnetic resonance (NMR) and high performance liquid chromatography studies of the three isomers. NMR, infrared and ultraviolet spectra of them were presented.
4 citations
Journal Article•
3 citations
Patent•
22 Sep 1977
TL;DR: In this paper, an intermediate polyurethane layer is placed between reaction layer of reaction paper and silicone layer, intermediate layer adheres to reaction layer, is neutral, w.r.t. reaction system and is crosslinked by silicone layer.
Abstract: Separating paper esp. for self-adhesive labels, foils and papers consists of a chemical colour reaction paper which is siliconised on at least one side, including the reaction system side. An intermediate polyurethane layer is placed between reaction layer of reaction paper and silicone layer. Intermediate layer adheres to reaction layer, is neutral, w.r.t. reaction system and is crosslinked by silicone layer. Siliconised prod. is used as cover-paper and can also serve as duplicating copy.
Patent•
27 Oct 1977
TL;DR: In this paper, the authors describe SF-1540 derivatives, having an optical rotation in chloroform [alpha] 0D of +21 deg., elementary analysis; C, 66.69% by weight; H, 8.62% by value; N, 1.68% by score; O, 23,96% by scoring; positive to the color reaction with potassium permanganate and sulfuric acid Negative to ninhydrin; slightly soluble in water, soluble in methanol, ethanol, acetone, etc
Abstract: PURPOSE:Antibiotic substance SF-1540 derivatives, having an optical rotation in chloroform [alpha] 0D of+21 deg.; elementary analysis; C, 66.69% by weight; H, 8.62% by weight; N, 1.68% by weight; O, 23,96% by weight; positive to the color reaction with potassium permanganate and sulfuric acid Negative to ninhydrin; slightly soluble in water, soluble in methanol, ethanol, acetone, etc
Patent•
12 Sep 1977
TL;DR: An antibiotic aplasmomycin and its metal derivatives were used in this article to solve the problem of antibiotic resistance to chloroform and ethylacetate, and were shown to be positive to the sulfuric acid-vaniline color reaction.
Abstract: PURPOSE:An antibiotic aplasmomycin and its metal derivatives. The elementary composition; C 59.87%, H 7.79% B, 1.44%, and Na 2.76%: molecular weight 820: melting point 283-285 deg.C: specific rotatory power [alpha] 3D+225 deg.: soluble to chloroform and ethylacetate: insoluble to water; positive to the sulfuric acid-vaniline color reaction: negative to the ferric chloride color reaction: colorless needle crystal
TL;DR: In this paper, a new indicator tube developed as an application of this reaction will be used conveniently for the detection of nitrogen dioxide in the field of industrial hygiene, which can be used for the purpose of detecting nitrogen dioxide.
Abstract: Polyvinylcarbazole reacts selectively with nitrogen dioxide and develops a yellow color The color producing components are identified to be nitro derivatives of the polymer A new indicator tube developed as an application of this reaction will be used conveniently for the detection of nitrogen dioxide in the field of industrial hygiene
TL;DR: In this article, a modification of the indophenol blue colour reaction was used to determine ammonia released by a semi-micro Kjeldahl digestion method which uses equipment which is cheap to construct.
Abstract: A method is described for rapid, total nitrogen determinations on samples of biological materials. A modification of the indophenol blue colour reaction is used to determine ammonia released by a semi-micro Kjeldahl digestion method which uses equipment which is cheap to construct. Using the procedure one worker can analyse 40 samples per hour. Recovery of nitrogen from a standard lysine solution was 98.3 %.