Aldehydes reaction with hydrogen sulfide

The reaction of hydrogen sulfide with aziridines in the presence of aldehydes or ketones provides a simple route to two-substituted thiazohdines (2,114-116). 

Eq. (48)1. Several reactions of hydrogen sulfide with acetylenic esters have been studied. The reaction of hydrogen sulfide with methyl propiolate, for example, gives rise to a simple 1 2 adduct (328) [Eq. (49)]. In the presence of aromatic aldehydes, HjS reacts with... 

Reaction of various aldehydes with hydrogen sulfide leads to substituted thiophenes, dihydrothiophenes, dithiolanes and trithiolane, as well as to six-membered ring thiopyran derivatives and dithiins. Ledl (33) obtained 2,4-dimethylthiophene (1, R Me) as a product of the reaction of propionaldehyde with hydrogen sulfide in the presence of ammonia. Sultan (29) reported the formation of 2,4-diethylthiophene (1, R - Et), 2,4-dibutyl-thiophene (1, R - Bu), and their dehydro derivatives from the reaction of ammonium sulfide with butyraldehyde and caproaldehyde (hexanal), respectively. The mechanism suggested for their formation is depicted in Scheme 1. Space limitations do not allow us to discuss the mechanism here in detail (for additional information, see ref. 29). 

Examples of aldehydes used to obtain the respective heterocycles are mentioned directly in the text. This work. KIP values are Kovdts indices on a polar column (FFAP) the values in parentheses are estimates based on additivity of index increments. Base peak and main fragments. Unless indicated otherwise, the mass spectra were obtained in this work and are in agreement with the literature data (see the ref.). %ot reported. Literature data. First isomer. Second isomer. Found by Ledl (33) after the reaction of acetaldehyde with hydrogen sulfide. 

The conversion of pyrans to thiopyrans can be accomplished only in the 4H series by the reaction of a 4//-pyran with hydrogen sulfide or P4SI0. The first procedure was successfully used for the preparation of 4//-thiopyrans 22,326 45,327 47,327 49 (n = 2),60-326 55,327 and 339.60-326 The second approach applied to 4//-pyran 85b provided 20% of 4//-thiopyran 3,5-dicarbox-aldehyde 340.85... 

Finally, heating of amino acids can produce volatiles Including aldehydes, amines and hydrogen sulfide. One minor, but Important, flavor generating pathway Involves the Strecker degradation of an amino acid as shown in Figure 2. In this reaction, an alpha amino acid reacts with an alpha dicarbonyl at an elevated temperature to produce an aldehyde (one carbon less than the amino acid) as well as an alpha amino ketone. These products can react further to yield Important heterocyclic aroma chemicals such as pyrazines, thlazoles, and dihydrofuranones. 

Spectra from the chemiluminescent gas phase reactions at 0,5 torr, of ozone with ethylene, tetramethylethylene, trans-2-hutene, and methyl mercaptan at room temperature are presented, and a summary of the general features of the emissions obtained from reaction in the gas phase of ozone with fourteen different olefins is given. The emitting species in the ozone-olefin reactions have been tentatively identified as electronically excited aldehydes, ketones, and a-dicarbonyl compounds. The reaction of ozone with hydrogen sulfide, methyl mercaptan, and dimethylsulfide produces sulfur dioxide in its singlet excited state. 

Reaction of an alkene with ozone leads to a 1,2,3-trioxolane, which rearranges to a 1,2,4-trioxolane (an ozonide). Subsequent treatment with hydrogen peroxide or with dimethyl sulfide leads to an aldehyde, ketone, or carboxylic acid product. When an ozonide contains a C-H unit, oxidation with hydrogen peroxide leads to a carboxylic acid, but reaction with dimethyl sulfide leads to an aldehyde 51, 52, 53, 54, 78,82,83,117. 

Thiophenes are formed by different reactions. The general reaction is that of furan derivatives with hydrogen sulfide (Figure 8.72). This mechanism is assumed, for example, in the formation of some thiophene derivatives from 4-hydroxy-2//-furan-3-ones. Alkylth-iophenes substituted in positions C-2 and C-3 may arise in reactions of 2-mercaptoethanal with unsaturated aldehydes, such as acrolein or but-2-enal (Figure 8.73). 2-Mercaptoethanal is a product of Strecker degradation of cysteine. 

Other modifications of the polyamines include limited addition of alkylene oxide to yield the corresponding hydroxyalkyl derivatives (225) and cyanoethylation of DETA or TETA, usuaHy by reaction with acrylonitrile [107-13-1/, to give derivatives providing longer pot Hfe and better wetting of glass (226). Also included are ketimines, made by the reaction of EDA with acetone for example. These derivatives can also be hydrogenated, as in the case of the equimolar adducts of DETA and methyl isobutyl ketone [108-10-1] or methyl isoamyl ketone [110-12-3] (221 or used as is to provide moisture cure performance. Mannich bases prepared from a phenol, formaldehyde and a polyamine are also used, such as the hardener prepared from cresol, DETA, and formaldehyde (228). Other modifications of polyamines for use as epoxy hardeners include reaction with aldehydes (229), epoxidized fatty nitriles (230), aromatic monoisocyanates (231), or propylene sulfide [1072-43-1] (232). 

Paint and varnish manufacturing Resin manufacturing closed reaction vessel Varnish cooldng-open or closed vessels Solvent thinning Acrolein, other aldehydes and fatty acids (odors), phthalic anhydride (sublimed) Ketones, fatty acids, formic acids, acetic acid, glycerine, acrolein, other aldehydes, phenols and terpenes from tall oils, hydrogen sulfide, alkyl sulfide, butyl mercaptan, and thiofen (odors) Olefins, branched-chain aromatics and ketones (odors), solvents Exhaust systems with scrubbers and fume burners Exhaust system with scrubbers and fume burners close-fitting hoods required for open kettles Exhaust system with fume burners... 

Reactions with Aldehydes, Hydrogen Sulfide, and Ammonia (or Ammonium Sulfide)... 

Five- and Six-Membered Ring Heterocycles with One, Two, or Three Sulfur Atoms. A summary of the various sulfur heterocycles formed from aldehydes in the presence of hydrogen sulfide and the corresponding analytical data are presented in Table I. Examples of aldehydes used in this reaction include propionaldehyde, butyraldehyde and caproaldehyde. 

The symmetrical compounds (17, R = R = R ) are formed from an aldehyde and ammonium sulfide (2,29,35) or hydrogen sulfide and ammonia (33), Thialdine (17, R - R - R = Me) is an important aroma compound found in the volatiles of beef broth (48), pressure-cooked meat (49), and fried chicken (50), It is also obtained from acetaldehyde (2,29,37) or from B-mercaptoacetaldehyde and ammonium sulfide (37), In our experiments, it was synthesized as a white powder from a reaction of acetaldehyde with ammonium sulfide in 60% yield. 

Asinger s studies demonstrated that product formation is sensitive to the ratio of sulfur to ketone (1), the structure of the ketone, the replacement of ammonia by amines, the temperature and the medium. Room temperature (20-25 °C) reactions in which the ratio of sulfur to ketones is 0.5 favors the formation of 3-thiazoline, 2, as shown in Figure 1. The formation of 5-alkylidene-3-thiazolines, 3, sometimes competes with the formation of 3-thiazolines such is the case when aryl ketones such as l-phenylpropan-2-one and l-phenylbutan-2-one are employed (4). Also the additional presence of hydrogen sulfide promotes the generation of 1,2,4-trithiolanes and 1,2,4,5-tetrathiolanes from ketones ana aldehydes at the expense of 3-thiazoline formation (11-12). Increasing the S/ketone ratio to 8 favors the formation of the 3-imidazoline-5-thione (5), a product which has a greater tendency to result from aryl methyl ketones (3). 

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