Hydrogen sulfide anion

Inhalation is the most common route of hydrogen sulfide exposure. Hydrogen sulfide is absorbed rapidly through the lungs (ATSDR 1999). It dissociates at physiologic pH to the hydrogen sulfide anion (Lide 1991), which is probably the absorbed form (WHO 1987). The absorption of hydrogen sulfide in humans and animals has not been quantitatively characterized. 

In that vein, thiols are routinely prepared by Sn2 substitution reactions with the hydrogen sulfide anion (HS ) serving as a nucleophile to displace halogen (frequently iodine) from the corresponding alkyl halide, as in the reaction of 1 -iodobutane to produce butanethiol (Equation 8.57). 

Interestingly, the hydrogen sulfide anion (HS ) is a strong enough base to depro-tonate the thiol formed (Equation 8.58). 

MSH (a metal hydrogen sulfide a source of the nucleophilic anion HS )... 

Hydrogen sulfide ion HS and anions of the type RS are substantially less basic than hydroxide ion and react with both primary and secondary alkyl halides to give mainly substitution products... 

Ma.nufa.cture. The preferred method for making nickel sulfate is adding nickel powder to hot dilute sulfuric acid. Adding sulfuric acid to nickel powder in hot water enhances the formation of H2S. Hydrogen sulfide always forms as a by-product upon reaction of metallic nickel and sulfuric acid. The hberated hydrogen is absorbed by the metal and then reduces the sulfate anion to H2S. 

Hydrogen Sulfide HjS Cause of rotten egg odor corrosion Aeration, chlorination, highly basic anion exchange... 

First, mention should be made of the metathetical reaction, replacing an anion of a pyrylium salt by another-, when the solubility of the latter salt is lower than that of the former, the conversion is easy. In the opposite case, one has to find a solvent in which the solubilities are reversed (perchlorates are less soluble in water than chloroferrates or iodides, but in concentrated hydrochloric or hydroidic acids, respectively, the situation is reversed For preparing chlorides which are usually readily soluble salts, one can treat the less soluble chloroferrates with hydrogen sulfide or hydroxylamine. Another method is to obtain the pseudo base in an organic solvent and to treat it with an anhydrous acid. 

This fact gives enough reason to suppose that the reaction of hydrogen sulfide addition to nitrile groups starts with the attack of the nucleophilic mercapto anion... 

This, naturally, results in an increased electrophilicity of the nitrile group and also creates favourable conditions for the nucleophilic attack of the mercapto anion and an easy addition of hydrogen sulfide in accordance with the above scheme. The activation energy of the thioamidation of the model compounds is much higher (for glutarodinitrile — 11,8 [49,4] and for trinitrile - 7,97 kcal/mol [33,4 kJ/mol]) than in PAN (6,18 kcal/mol [25,9 kJ/mol]). 

Treatment of nitriles with gaseous hydrogen sulfide in the presence of anion exchange resin (Dowex 1X8, SH from) at room temperature affords the corresponding primary thioamides.27 Treatment of nitriles with 70% sodium hydrosulfide hydrate and magnesium chloride hexahydrate in DMF or methanol affords primary thioamides in high yields.28 Primary thioamides have been... 

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