Biodegradability groups

Figure 7. Conformations of the BHC (HCH) isomers and recent analogues of the aaaeee (lindane) structure, some of which have additional biodegradable groups (54)...

Klopman G, S Wang and D M Balthasar 1992. Estimation of Aqueous Solubility of Organic Molecule by the Group Contribution Approach. Application to the Study of Biodegradation. Journal c Chemical Information and Computer Science 32 474-482. 

In 1991, the European fabric softener market took a sharp turn. Producers in Germany, the Netherlands, and later in Austria and Switzerland voluntarily gave up the use of DHTDMAC (238) because of pressure from local environmental authorities, who gave an environmentally hazardous classification to DHTDMAC. A number of esterquats were developed as candidates to become successors to DHTDMAC (see Fig. 1). The ester group facihtates biodegradation. 

Nontoxic ahphatic compounds containing carboxyl, ester, or hydroxyl groups are readily biodegradable. Those with dicarboxyhc groups require longer acclimation times than those with a single carboxyl group. 

Fig. 3. Mechanisms for polymer degradation. The illustration is a schematic representation of three degradation mechanisms I, cleavage of cross-links II, hydrolysis, ionisa tion, or protonation of pendent groups III, backbone cleavage. Actual biodegradation may be a combination of these mechanisms.

As laboratory experiments have shown, the position of the sulfophenyl group on the alkyl chain has great importance for both biodegradation and eco-toxicology [273,292-295]. These experiments further show that LAB catabo-lites (e.g., sulfophenylcarbonic acids) have a significantly lower ecotoxicity than the original surfactant [288,294]. 

Consequently, it is generally accepted that the chemical nature of the hydrophilic group affects biodegradability to a minor extent and that the hydrophobic group is the responsible for a ready biodegradation. 

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