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Dihydrazides

SpecialChem / Nov 2, 2005

Dihydrazides are represented by the active group: where R is can be any polyvalent organic radical, preferably one derived from a carboxylic acid. Carboxylic-acid esters are reacted with hydrazine hydrate in an alcohol solution using a catalyst and water extraction. The most common dihydrazides include adipic acid dihydrazide (ADH), derived from adipic acid; sebacic acid dihydrazide (SDH); valine dihydrazide (VDH), derived from the amino acid valine; and isophthalic dihydrazide (IDH). The aliphatic R group can be of any length. For example, when the R group is only carbon, the resulting compound is carbodihydrazide (CDH), the fastest dihydrazide. Or the group is R as long as C-18 has been reported, as in icosanedioic acid dihydrazide (LDH). Although hydrazine is a suspected carcinogen, the safety of ADH has been well established.2 IDH is approved by the FDA for indirect food contact when used to cure epoxy resins under 21 CFR 175.300. In epoxy resins, dihydrazides are typically formulated to 1/4 of dihydrazide to each epoxy equivalent.

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