Sulfur-containing Acids

Acetyl chloride frequently contains 1—2% by weight of acetic acid or hydrochloric acid. Phosphoms or sulfur-containing acids may also be present in the commercial material. A simple test for purity involves addition of a few drops of Crystal Violet solution in CHCl. Pure acetyl chloride will retain the color for as long as 10 min, but hydrochloric, sulfuric, or acetic acid will cause the solution to become first green, then yellow (34). 

We could write many more reactions involving these species, but, as will be seen, the ones above are sufficient. We will also assume a total sulfur concentration of 0.010 M, but we need to know how pH affects the distribution of sulfur-containing acids and bases. For any acid... 

For caramel aroma, aliphatic amino acids were required for meaty, sulfur-containing ones for nutty, amides or hydroxy ones for meaty and vegetable, sulfur-containing and aromatic ones for fragrant, aromatic ones for roasted vegetable, aromatic, sulfur-containing, acid, aliphatic and basic or amide ones for baked potato, sulfur-containing ones and for baked, secondary ones. In each case, additional amino acids were or were not present in the mixtures heated. 

When adsorbed from the gas phase sulfur-containing acids form the most stable neutral complexes, whereas a similar process in solution is accompanied by rearrangement into a zwitterionic structure. It should be noted that adsorbed cystine molecules preserve their disulfide bridges, indicating that their native structure remains under interaction with the silica surface. 

X-ray analysis of the washed specimen from which the yellow color leached out showed some slight diminishing of aluminum and virtually no sulfur, whereas sulfur was present in the remnant fabric. Although it is possible that sulfur was in some way connected with the yellow dyestuff molecule, it may also be that a sulfur-containing acid was used to affix the yellow dyestuff on the cloth. Acid dyes are so-named because they are set with acids, and sulfuric acid commonly was used at this time to serve this function (8-12). 

Because of the relatively narrow range of chemical shifts observed for the esters of the various sulfur containing acids, the functional group of such compounds is best characterized through the analysis of their infrared spectra. 

Secondary antioxidants work by preventing the formation of free radicals. Some of them will decompose hydroperoxides by a safe reaction before they get the chance to generate fiee radicals. Hydroperoxide decomposers fall into two categories some act by a catalytic mechanism. These include the sulfur-containing acids that are formed by the oxidation of thiodipropionate esters or metal dialkyldithiocarbamates. The last-mentioned, if they contain a transition metal, are also ultraviolet light absorbers. An alternative type of hydroperoxide decomposer acts by a stoichiometric mechanism, namely the phosphite esters. 

Table A,6, Nitroprusside test (urine). This test reacts with sulfur containing acids to form pink to purple color complexes ...

Tressl R., Holzer M., Apetz M. Formation of flavor components in asparagus. 1. Biosynthesis of sulfur-containing acids in asparagus. Journal of Agricultural and Food Chemistry, 25 455-459 (1977). 

Hydroperoxide decomposers such as phosphites [53], organic sulfides [54], and sulfur containing acids [54] are used for thermal stabilization of polymer chains. Specifically reactions such as... 

UNSUBSTITUTED TRIORGANOTIN CARBOXYLATES DERIVED FROM OXYGEN AND SULFUR CONTAINING ACIDS... 

The compounds are listed in Table 202. Additional triorganotin carboxylates of substituted oxygen and sulfur containing acids are listed in Subsection. 3-5-1 3 and in Tables 200, 205 and 206. References to such carboxylates may be found in Chapter 8.1. 

Table 202. Unsubstituted Triorganotin Carboxylates Derived from Oxygen and Sulfur Containing Acids RaSnOaCR ... 

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