Preservatives quaternary amines

Temporary hair dye products usually are formulated at a neutral or slightly acidic pH. Besides the dyes, the formulations may contain a small amount of a quaternary amine to neutralize the negative charge on the dyes, a fragrance, a small amount of a solvent or surfactant to solubilize the fragrance, and a preservative (Table 6). 

As described previously, the origins of the three types of curare are the extracts of Chondodendron (Menispermaceae) and/or Strychnos (Loganiaceae) plants. Among them, the toxic components of Strychnos plants are C-curarine and C-toxiferine I, etc.These constituents are alkaloids derived from tryptophan and are described in the next (Section 2.15).The C- is the initial of calabash. On the other hand, the toxic principle of tubocu-rare is d-tubocurarine, an alkaloid derived from phenylalanine. The alkaloid was first isolated as a hydrochloride from tubocurare and is preserved in the Museum of the British Society of Pharmacy [1]. The chemical structure of d-tubocurarine was first proposed as a bisbenzylisoquinoline with two quaternary ammonium moieties. This was revised in 1970 to be the structure with one tertiary and one quaternary amine after X-ray crystallographic analysis [2]. 

Benzylic amines are resistant to hydrogenolysis under Birch reduction conditions, unless the amine is quaternary, as in the Emde reaction. A means of preserving an aryl carbonyl group is therefore to protect it as an aminal derivative. An illustration is provided by the preparation of aldehyde (213), an important flavor constituent of cumin, as outlined in Scheme 47." ... 

A number of fatty amines and their derivatives, especially quaternary ammonium compounds, are widely used in formulations for the control of bacteria, fungi, viruses and algae, in disinfectant/sanitizers and wood-preservation applications. Table 14.3 presents the fatty amines and derivatives which are frequently used in biocidal formulations. 

A unique advantage of amine oxides is their ability to be formulated with quaternary preservatives without inhibition of the cationic. Although there are other nonionic emulsifiers that can be used in cosmetic emulsions compatible with quaternary emulsions, very frequently the preservative activity of the quat is inhibited by the nonionics. Not only are the amine oxides not inhibited by the quats, but by themselves being slightly cationic at acid pHs, they actually enhance the preservative action of quaternaries. 

The antimicrobial efficacy of the amine-formaldehyde reaction products essentially corresponds to the formaldehyde content of these compounds. Known exceptions are HTA, hexahydro-oxadiazines and octahydro-s-tetrazines, which derive from ammonia respectively certain alkylolhydrazines (Paulus, 1980) here the detection of formaldehyde by the Taimenbaum methods gives a negative result, which means that these substances have no significant antimicrobial effect at neutral to alkaline pH they release formaldehyde in acidic media only. This pH dependency is broken off, if, for example, HTA is quatemized (Jacobs et al., 1916). In contrast to HTA the quaternary hexaminium salts release formaldehyde widely independent of pH and therefore may be used as preservatives also for media of neutral to alkaline pH. They are not comparable with the surface active conventional quaternary ammonium compounds (QACs see Section 16.1)... 

Surface active compounds are often effective to potentiate the activity of the microbiddes. It is observed that the lower the content of volatile organic carbon in a paint the more important is the formulation of a preservative to transport the active ingredient to the location within the multiphase system where it is needed. Frequently, an optimum balance of membrane-activity and reactivity of the second active ingredient against microorganisms in complex matrices has to be found. It can be demonstrated that surface active compounds [II, 18.] like e.g. quaternary ammonium salts, fatty amine derivatives, ethoxylated alcohols or dodecylbenzene sulfonic add potentiates the activity of bactericides like BIT, MIT. 

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