نتایج جستجو برای: mercaptan
تعداد نتایج: 532 فیلتر نتایج به سال:
By the synergistic catalysis of samarium ion and mercaptan, a series of 5-oxoalkanals was converted to (substituted) delta-lactones in efficient and stereoselective manners. This one-pot procedure comprises a sequence of acetalization, Tishchenko reaction and lactonization. The deliberative use of mercaptan, by comparison with alcohol, is advantageous to facilitate the catalytic cycle. The reac...
As oil and gas reserves become depleted, producers are increasingly driven to process difficult or unconventional petrochemical fuel sources to sell to the market in order to meet rising demand. One such source is the production of sour gas wells that contain high levels of mercaptan (thiol) species. In sour gas processing applications, a waste acid gas stream (ie. a stream containing high conc...
Mercaptans are commonly present in petroleum products. Their foul odor and highly corrosive nature make them the most undesirable sulfur compounds so they should be removed because of environmental issues. Merox process is used for oxidation of mercaptans to disulfide using air in the presence of alkaline solution and Merox catalyst. In this paper, due to lack of information about the kinet...
The stability of the coffee flavor compound furfuryl mercaptan has been investigated in aqueous solutions under Fenton-type reaction conditions. The impact of hydrogen peroxide, iron, ascorbic acid, and ethylenediaminetetraacetic acid was studied in various combinations of reagents and temperature. Furfuryl mercaptan reacts readily under Fenton-type reaction conditions, leading to up to 90% deg...
A deodorizing substance in black cumin (Nigella sativa L.), a spice for curry and vegetable foods in Southwest Asia, was examined. The essential oil prepared from the seeds of this plant exhibited strong deodorizing activity against methyl mercaptan, which is a main factor in oral malodor. After purification with silica gel column chromatography, the active substance in black cumin seed oil was...
Background: Tert-butyl mercaptan is one of the frequently used odorants derived from natural gases. It has been declared as a health hazard by the Occupational Safety and Health Administration (OSHA) in the USA. There is not much information available about the mercaptans long-term toxicity secondary to occupational exposure. This study was conducted to evaluate the oxidative stress caused by m...
The deodorizing mechanism of (-)-epigallocatechin gallate (ECCg), the main constituent of a green tea extract, against methyl mercaptan (CH,SH) was investigated. EGCg showed deodorizing activity against CH3SH by a chemica] reaction between EGCg and CH3SH. The non-volatile reaction products were identified to be compounds introducing a methylthio andlor a methylsulfinyl group into the B ring of ...
A Stereospecific Synthesis of Pantothenic Acid Derivatives in Prebiotic Molecular Evolution on Earth
A set of chemical reactions is proposed to account for the formation of pantothenic acid derivatives from a primeval atmosphere composed of ammonia, formaldehyde, propyne, ethyne, hydrogen sulfide, hydrogen and water. Three precursor molecules are initially formed; a di-adduct of propyne and the catalyst Mg.porphin, azetidine2one, and 2-amino ethyl mercaptan. These then react sequentially to fo...
Part II of this paper will concern the solution of limiting dimensions for micro-meteorites in an atmosphere of constant temperature gradient and in the general case. A critical discussion of the assumptions adopted here will be included as well as some elaboration of the numerical results. * This paper was written as a part of the investigation for United States Naval Ordnance Contract-10449-0...
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