Of quaternary ammonium compounds

The first reported synthesis of acrylonitrile [107-13-1] (qv) and polyacrylonitrile [25014-41-9] (PAN) was in 1894. The polymer received Htde attention for a number of years, until shortly before World War II, because there were no known solvents and the polymer decomposes before reaching its melting point. The first breakthrough in developing solvents for PAN occurred at I. G. Farbenindustrie where fibers made from the polymer were dissolved in aqueous solutions of quaternary ammonium compounds, such as ben2ylpyridinium chloride, or of metal salts, such as lithium bromide, sodium thiocyanate, and aluminum perchlorate. Early interest in acrylonitrile polymers (qv), however, was based primarily on its use in synthetic mbber (see Elastomers, synthetic). 

There are a vast number of quaternary ammonium compounds or quaternaries (1). Many are naturally occurring and have been found to be cmcial in biochemical reactions necessary for sustaining life. A wide range of quaternaries are also produced synthetically and are commercially available. Over 204,000 metric tons of quaternary ammonium compounds are produced aimuaHy in the United States (2). These have many diverse appHcations. Most are eventually formulated and make their way to the marketplace to be sold in consumer products. AppHcations range from cosmetics (qv) to hair preparations (qv) to clothes softeners, sanitizers for eating utensils, and asphalt emulsions. 

There are no universally accepted wet analytical methods for the characteri2ation of quaternary ammonium compounds. The American Oil Chemists Society (AOCS) has estabhshed, however, a number of appHcable tests (180). These include sampling, color, moisture, amine value, ash, iodine value, average molecular weight, pH, and flash point. 

Mass spectral analysis of quaternary ammonium compounds can be achieved by fast-atom bombardment (fab) ms (189,190). This technique rehes on bombarding a solution of the molecule, usually in glycerol [56-81-5] or y -nitroben2yl alcohol [619-25-0], with argon and detecting the parent cation plus a proton (MH ). A more recent technique has been reported (191), in which information on the stmcture of the quaternary compounds is obtained indirectly through cluster-ion formation detected via Hquid secondary ion mass spectrometry (Isims) experiments. 

The threat of accidental misuse of quaternary ammonium compounds coupled with potential harmful effects to sensitive species of fish and invertebrates has prompted some concern. Industry has responded with an effort to replace the questionable compounds with those of a more environmentally friendly nature. Newer classes of quaternaries, eg, esters (206) and betaine esters (207), have been developed. These materials are more readily biodegraded. The mechanisms of antimicrobial activity and hydrolysis of these compounds have been studied (207). AppHcations as surface disinfectants, antimicrobials, and in vitro microbiocidals have also been reported. Examples of ester-type quaternaries are shown in Figure 1. 

A wide variety of methods are available for the preparation of quaternary ammonium compounds (218—220). Significantly fewer can be used on a commercial scale. A summary of the most commonly used commercial methods is given herein. 

Synthesis and Manufacture of Amines. The chemical and busiaess segments of amines (qv) and quaternaries are so closely linked that it is difficult to consider these separately. The majority of commercially produced amines origiaate from three amine raw materials natural fats and oils, a-olefins, and fatty alcohols. Most large commercial manufacturers of quaternary ammonium compounds are fully back-iategrated to at least one of these three sources of amines. The amines are then used to produce a wide array of commercially available quaternary ammonium compounds. Some iadividual quaternary ammonium compounds can be produced by more than one synthetic route. 

The single largest market for quaternary ammonium compounds is as fabric softeners. In 1993 this market accounted for over 50,000 metric tons of quaternaries in the United States (235). Consumption of these products is increasing at an annual rate of about 2—3%. The hair care market consumed over 9000 metric tons of quaternary ammonium compounds in 1992 (236). The annual consumption for organoclays is estimated at 12,700 metric tons (237). Esterquats have begun to gain market share in Western Europe and growth is expected to continue. 

Uses of quaternary ammonium compounds range from surfactants to germicides and encompass a number of diverse industries (see Table 1). 

An alternative route from l-aminoanthraquinone (17) has been proposed. Methylation is preferably carried out usiag dimethyl sulfate or methyl iodide ia an organic solvent ia the presence of alkah metal hydroxide and a catalytic amount of quaternary ammonium compound (98). 

Acids such as sulfuric or nitric acids or bases such as sodium hydroxide may catalyze the hydrolysis of PET. It has been demonstrated that the rate of alkaline PET hydrolysis increases in the presence of quaternary ammonium compounds.26 27 Niu et al.26 reported an increase in the rate of alkaline PET degradation in the presence of dodecylbenzyldimethylammonium chloride at 80°C. Polk et al.27 reported increases in the rate of sodium hydroxide depolymerization of PET in the presence of trioctylmethylammonium chloride, trioctyl-methylammonium bromide, and hexadecyltrimethylammonium bromide at 80° C. 

In the case of quaternary ammonium compounds the chromatograms can be treated afterwards with sodium nitrite solution in order to intensify the color [27]. 

HZ Sommer, HI Lipp, LL Jackson. Alkylation of amines. A general exhaustive alkylation method for the synthesis of quaternary ammonium compounds, (effects of hindrance) J Org Chem 36, 824, 1971. 

The simultaneous ionic and covalent character of quaternary ammonium compounds (197a) is central to most of their applications. TV-Quatemized heteroaromatic compounds possess many of the properties of 197a, and will be mentioned occasionaly in this chapter. In Table 4 are listed some quaternary ammonium compounds that have found industrial application. Many analytical methods make use of this class of compounds both as essential reagents or as accessories however, in the present chapter quaternary ammonium compounds will appear only as analytes. 

The use of ion pairing agents, such as sodium benzenesulfonate, may be helpful in the analysis of complex mixtures of quaternary ammonium compounds, as they modify their retention times418. 

The use of suppressors in ion chromatography of quaternary ammonium compounds can be of advantage. These are ion exchange membranes that introduce hydroxide ions instead of the counterion present in the analyte. This simplifies the mixture and enhances the electrolytic conductivity of the sample. The effluent of the suppressor may be nebulized and subjected to field-assisted evaporation, yielding a cloud of ions suspended in the gas phase, which can be introduced into an MS analyzer designed for work at atmospheric pressure. Both the molecular weight and the structure of the quaternary cations can be determined by this method419. 

Haruta H, Yagi H, Iwata T, Tamura S. 1974. Syntheses and plant growth retardant activities of quaternary ammonium compounds derived from a-ionone and isophorone. Agric Biol Chem 38 417-422. 

Long-chain alkyl chlorides can be used lor the synthesis of various amines, while benzyl chloride is used for production of quaternary ammonium compounds. Alkyl chlorides are used for the formation of organometallics, including the Grignard reagents as well as for alkylation of aromatics. One of the important reactions or phosgene is with diamines for production of diisocyunates (polyurethanes). 

QUATERNARY AMMONIUM COMPOUNDS. There are a vast number of quaternary ammonium compounds (quaternaries). Many are naturally occurring and have been found to be crucial in biochemical reactions necessary for sustaining life. Many quaternaries are also produced synthetically and are commercially available. 

Mass spectral analysis of quaternary ammonium compounds can be achieved by last-atom bombardment (lab) ms. 

Most uses of quaternary ammonium compounds can be expected to lead to these compounds eventual release into wastewater treatment systems except for those used in drilling muds, Useful properties of the quaternaries as germicides can make these compounds potentially toxic to sewer treatment systems. It appears, however, that quaternary ammonium compounds are rapidly degraded in the environment and strongly sorbed by a wide variety of materials. 

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