Active hydrogen compounds halogenation

It is possible to use halogen-sensitive detectors in glc analysis of active hydrogen compounds by sdylating them with a halogenated sdylating agent, eg, CMDMS (9). 

Some of the most familiar reactions falling into the polycondensation class are those leading to polyamides derived from dicarboxylic acids and diamines, polyesters from glycols and dicarboxylic acids, polyurethanes from polyols and polyisocyanates, and polyureas from diamines and diisocyanates. Similar polymer formations utilizing bifunctional acid chlorides with polyols or polyamines also fall into this class. The condensations of aldehydes or ketones with a variety of active hydrogen compounds such as phenols and diamines are in this group. Some of the less familar polycondensation reactions include the formation of polyethers from bifunctional halogen compounds and the sodium salts of bis-phenols, and the addition of bis-thiols to diolefins under certain conditions. 

Among the oxidative procedures for preparing azo compounds are oxidation of aromatic amines with activated manganese dioxide oxidation of fluorinated aromatic amines with sodium hypochlorite oxidation of aromatic amines with peracids in the presence of cupric ions oxidation of hindered aliphatic amines with iodine pentafluoride oxidation of both aromatic and aliphatic hydrazine derivatives with a variety of reagents such as hydrogen peroxide, halogens or hypochlorites, mercuric oxide, A-bromosuccinimide, nitric acid, and oxides of nitrogen. 

In the reactions with aliphatic hydrogen-containing compounds such as hexane, and halogen compounds such as carbon tetrachloride, hydrogen and halogen respectively are abstracted from these compounds these are reactions characteristic of active free radicals. 

The only useful commercial catalyst now used is nickel, available at a 17-25% level on a support and suspended in hardened edible oil or tallow. This preserves the activity of the nickel in a form in which it can be safely and easily handled. Catalyst can be recovered and reused but will be less active. Reaction is usually effected at temperatures between 180°C and 200°C and at a pressure of about 0.3 MPa (3 bar). The catalyst is quickly poisoned by fatty acids, soaps, phospholipids, oxidized acids, sulfur compounds, halogen compounds, carbon monoxide, oxygen, and water. As a consequence, both the oil and the hydrogen should be as pure as possible. 

Acylation converts compounds with active hydrogen, for example, in the -SH into thioesters by reaction with carboxyl acids or their derivatives. The presence of a carbonyl group next to the halogenated carbon increases the ECD response. For thiols, using Af-methyl-bis(trifluoroacetamide) (MBTFA) is recommended. 

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