Thiochemicals

Since its development in cosmetics in the 1940s, thioglycolic acid has become a widespread thiochemical, used all over the world as the acid or in the form of its salts or esters. Because of the several derivatives of thioglycolic acid used, the market size for this chemical is often expressed in terms of thioglycolic acid equivalents. In 1994 the total world market was estimated at around 15,000 to 20,000 metric tons of thioglycolic acid equivalents. Some mercaptocarboxyhc acid and esters available are compiled in Table 2. 

Basic thiochemicals examples are sulfur dioxide, hydrogen sulfide, sodium sulfide, sodium thiosulfate, etc. 

To describe the full range of thiochemicals is beyond the scope of this entry, which will, therefore, place emphasis on the most common thiochemicals. This entry will cover mercaptans, sulfides, and polysulfides, while the next entry will cover sulfonic acids and its derivatives, some sulfoxides, mercaptoacids and their derivatives. The safety, health, and environmental issues for both entries are discussed at the end of this chapter. 

There are several methods for the preparation of mercaptans and sulfides. It is our intention here to emphasize only the most facile methods that are safe to operate commercially, use inexpensive raw materials, produce minimum by-products, and allow for simple and easy by-product handling. While the sources of sulfur for thiolation can be many, the most common ones are hydrogen sulfide (H2S), elemental sulfur, and carbon disulfide (CS2). H2S is a component of sour natural gas and can be separated for use in the manufacture of mercaptans and other sulfur chemicals. Additionally, H2S is generated in the many hydrode-sulfurizing units in a refinery. With minimal purification this could be used for the manufacture of thiochemicals. In many instances H2S is manufactured by either the Girdler or the Folkins processes ... 

Thiochemicals Mereapto Adds and Organosulfur (IV/VI) Compounds Table 4B Physical properties of selected sulfonic acids... 

Intermediate and Fine Chemicals acrylics, thiochemicals, peroxides and fluorinated products ... 

Uses Depilatory agent, reducing agent in cosmetics reagent for cold permanent hair waves/straighteners culture media Manuf/Distrib. Adept Sol ns. Alfa Chem http //www.aifachem.homepage.com Ashland http //www.ashchem.com Bruno Bock http //WWW. bock-thiochemicals. com Cos meti c Supplies USA... 

Manuf./Distrib. Bruno Bock http //www.bock-thiochemicals. com Ammonium thiosulfate CAS 7783-18-8 EINECS/ELINCS 231-982-0 Synonyms Ammonium hyposulfite Diammonium thiosulfate Thiosulfuric acid, diammonium salt Empirical H8N2O3S2 Formula (NH4)2S203... 

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