Fatty alkyl imidazolines

Carboxy amphoteric surfactants based on fatty alkyl imidazolines (imidazolinium surfactants) make up a large part of the amphoteric surfactants. Materials of this surfactant class are based on the imidazolines obtained by the condensation of fatty acids or their esters with aminoethyl ethanol amine. 

Imidazolinium betaines were initially described by Mannheimer, who obtained them from the reaction of fatty alkyl imidazolines with sodium chloroacetate [30,31]. 

Carboxyamphoteric surfactants based on fatty alkyl imidazolines ( imidazolinium surfactants) make up a large part of the amphoteric surfactants. The very divergent interpretation of their chemical structure is partly attributable to little-developed analytical procedures in the past, but is also a consequence of special processing methods by different manufacturers. Materials of this surfactant class are based on the imidazolines obtained by the condensation of fatty acids, or their esters, with AEEA. In Figures 12.4 and 12.5, a summary of the synthesis of amphoteric surfactants based on imidazolines [4,8] is presented. 

Imidazolinium betaines were initially obtained from the reaction of fatty alkyl imidazolines with sodium chloroacetate [10,11]. Their preparation in this manner, however, is not practiced. They can be prepared by the reaction of imidazoline with acrylic acid (Figure 12.11). The corresponding carboxyl ethyl betaine may be obtained, in —65% yield, by the electrophilic addition of acrylic acid on tertiary amine [35] (Figure 12.12). 

Fig. 3. Quatemaiies fiom amidoamines and imidazolines where R is a fatty alkyl group.

Many of the surfactants made from ethyleneamines contain the imidazoline stmcture or are prepared through an imidazoline intermediate. Various 2-alkyl-imidazolines and their salts prepared mainly from EDA or monoethoxylated EDA are reported to have good foaming properties (292—295). Ethyleneamine-based imida zolines are also important intermediates for surfactants used in shampoos by virtue of their mildness and good foaming characteristics. 2- Alkyl imidazolines made from DETA or monoethoxylated EDA and fatty acids or their methyl esters are the principal commercial intermediates (296—298). They are converted into shampoo surfactants commonly by reaction with one or two moles of sodium chloroacetate to yield amphoteric surfactants (299—301). The ease with which the imidazoline intermediates are hydrolyzed leads to arnidoamine-type stmctures when these derivatives are prepared under aqueous alkaline conditions. However, reaction of the imidazoline under anhydrous conditions with acryflc acid [79-10-7] to make salt-free, amphoteric products, leaves the imidazoline stmcture essentially intact. Certain polyamine derivatives also function as water-in-oil or od-in-water emulsifiers. These include the products of a reaction between DETA, TETA, or TEPA and fatty acids (302) or oxidized hydrocarbon wax (303). The amidoamine made from lauric acid [143-07-7] and DETA mono- and bis(2-ethylhexyl) phosphate is a very effective water-in-od emulsifier (304). 

Two major classes of amphoteric surfactants are derived from fatty alkyl hydroxyethyl imidazolines which, in turn, are produced from fatty acids and low molecular weight amines. Because fatty acids are fairly economic, the imidazoline derived amphoacetates tend to be less expensive than the iminodipropionates discussed above. Most imidazoline derived... 

In the selection of an appropriate corrosion inhibitor, an important consideration is the problem of adverse competition with other additives designed to adsorb on the liquid-metal interface. Extreme pressure and/or antiwear agents compete for the same sites as the corrosion inhibitor. Eatty amines are good corrosion inhibitors in this type of environment. However, their adverse effect on the performance of ZDDP additives often prohibits their use. Half esters or amides of dodecylsuccinic acid, phosphate esters or thiophosphates are frequently employed. A combination of inhibitors is sometimes used, for example, fatty carboxylic acids or the dimer/trimer analogues of the unsaturated acids, e.g. oleic, used in conjunction with an amine such as an ethanolamine or alkyl amine, or amide such as alkyl imidazoline and sarcosines, Eig. 6.7. Shorter chain carboxylic acid and amines are used as volatile corrosion inhibitors. 

The synthesis of these surfactants involves several steps. The first step is the preparation of a substituted imidazoline, usually l-(hydroxyethyl)-2-alkyl imidazoline, starting from fatty acids or fatty acid methyl esters and aminoethylethanolamine (AEEA) (Figure 15.15). For the production of betaines, the choice of fatty material is in most cases hydrogenated coco fatty acid. The distribution composition of fatty acid chain lengths, given above in Table 15.2, is typical also for cocoam-phoacetates. 

The addition of acrylic acid to high-percentage imidazolines improves the existence of an imidazolinium betaine in the model substance l-hydroxyethyl-2-heptyl-imidazolinium-3-ethyl carbox-ylate through purification by vacuum distillation [36]. The preparation is carried out by heating the imidazoline derivative for several hours with a 5% excess of acrylic acid in the absence of water. More than 65% of the imidazolinium structure is retained depending on the length of the fatty alkyl chain. Open-chain reaction products are also formed, by application of excess acrylic add, depending on the reaction temperature. 

Nitrogen derivatives can be made directly from fatty acids and esters by reaction with polyamines and alcoholamines. Reaction of fatty acids with polyamines such as diethylenetriamine or aminoethylethanolamine leads to the formation of amidoamines, which can be cyclized through further condensation to give alkyl imidazolines [12-15]. Condensation with dimethylaminopropylamine affords alkylamidodimethylaminopropy-lamines, which are popular precursors to betaines and amine oxides (Figure 2.2). While imidazolines and amidoamine derivatives have lost ground to esterquats in fabric... 

The foam-holding characteristics of foam from surfactants in oil field jobs can be tailored by adding an imidazoline-based amphoacetate surfactant. Amphoacetates are a special class of amphoteric tensides (Figure 16-1). Imidazoles, such as 2-heptylimidazoline, are reacted with fatty acids under the ring opening. For alkylation, the imidazoline is reacted with, for example, chloroacetate [493]. 

One type of cationic surfactant was the fatty acid derivatives of polyamines. The properties of the derivatives of fatty acids and ethylenediamine have been described in the literature (7-9). It appeared from these reports that the 2-alkyl-2-imidazolines would not impart sufficient hydrophobicity to soils. However, the analogous series of homologous compounds from the fatty acids and diethylene-triamine (BETA) appeared likely to do so because of their higher molecular weight. 

Industrial surfactants find uses in almost every industry, from asphalt manufacturing to carpet fibers, from pulp and paper production to leather processing. Examples of the types of chemicals used as surfactants are fatty alcohol sulfates, alkanolamides, alkoxylates, sulfosuccinates, amines, quaternaries, phosphate esters, acid esters, blockcopolymers, betaines, imidazolines, alkyl sulfonates, etc. 

A number of nitrogen- and sulfur-containing heterocyclic compounds are effective corrosion inhibitors (62MI11502), the imidazolines and the benzotriazoles being particularly important types. The imidazolines are derived from ethyleneamines by reaction with fatty acids the free bases (53), the fatty acid salts (54), and various derivatives obtained by reaction with anhydrides, isocyanates or alkyl halides (55) are effective inhibitors. 

For personal care applications, the major products in this group are amphoacetates or amphodiacetates , generally based on alkyl hydroxyethyl imidazolines from either a whole coconut fatty acid distribution or a lauric cut. The ampho portion of their name is a convention established by the International Nomenclature Committee for Cosmetic Products (INCI) to indicate that they are derived from imidazoline structures. The INCI nomenclature applied to these materials, amphoacetate and amphodiacetate, is intended to give an indication of the stoichiometry used to produce them, either 1 or 2 mol of sodium chloroacetate is added to each mole of fatty imidazoline. Modern analytical methods have been used to determine the structure of these products and almost all of them are actually monoacetates . The main difference between amphoacetates and ampho diacetates is the composition of the by-products. 

The other major class of fatty imidazoline derived amphoteric surfactants is the amphopropionates. Again, the ampho portion of the name indicates that they are derived from imidazolines but, rather than being alkylated with sodium chloroacetate, they are carboxy-lated with an acrylate via the Michael reaction. A primary or secondary amine is added across the double bond of the acrylate to yield the beta-alanine derivative. 

The reaction conditions can be selected to maximise the formation of imidazoline cationics quatemised derivatives of which have some importance as cationic fabric softeners [22c, 98, 99, 102]. Surface-active tertiary amines can be formed from alkyl chlorides, acyl chlorides or fatty esters as can be illustrated by the following reactions ... 

Here the alkyl part originates generally of coconut or tallow fatty acids. If methyl fatty acids or glycerides are the precursors, the liberated methanol is separated whereas glycerol is generally retained in the final product. Similar betainic structures, along with imidazoline-type amphoterics, occur as condensation products of fatty imidazolines and chloroacetic acid, as mentioned above. 

A wide range of derivatives are prepared from alkyleneamines and poly(ethyleneamines) such as diethylene triamine (DETA), triethylenetetramine (TETA), imidazolines, amidoamines, and their ethoxylated and propoxylated derivatives as depicted in Scheme 1.7. Reaction products of fatty acids and their derivatives with DMAPA (see Section 1.6.1) can be quatemized with various alkylating agents to produce amidopropyl ammonium quaternaries, many of which have been patented and commercialized in a variety of applications, including personal care, fabric softening, and industrial/oil-fleld applications. 

Coconut fatty acids, monoester with tetraglycerol. See Polyglyceryl4 cocoate Coconut fatty acid, sodium salt. See Sodium cocoate Coconut fatty alcohol. See Coconut alcohol Coconut hydroxyethyl imidazoline. See Cocoyl hydroxyethyl imidazoline Coconut imidazoline betaine. See Sodium cocoamphoacetate Coconut monoethanoiamide. See Cocamide MEA Coconut monoisopropanolamide. See Cocamide MIPA Coconut oil. See Coconut (Cocos nucifera) oil Coconut oil acids. See Coconut acid Coconut oil acids, potassium salts. See Potassium cocoate (Coconut oil alkyl) trimethylammonium methyl sulfate. See Cocotrimonium methosulfate... 

Imidazoline derivatives can be hydrolyzed with sulfuric acid into their starting materials diamines and fatty acids. These can then be analyzed by gas chromatography, as described in Chapter 8. Some impurities, as well as the main components, can be detected (22,23). As described in Chapter 9, TLC may be used for semiquantitative determination of various compounds main component, imidazoline intermediate, secondary and tertiary amide intermediates, and A-hydroxyethylethylenediamine starting material (5). HPLC methods used to analyze imidazoline derivatives are summarized in Chapter 7. Separation is typically according to the length of the alkyl chain, with further differentiation of impurities and intermediates within each alkyl chain group (24,25). HPLC has been demonstrated for the determination of free dimethylaminopropylamine after derivatization with salicylaldehyde (26). 

Arens, M., R. Spilker, Fatty acid amidopropylbetaines—determination of fatty acid amidopro-pylamine—collaboration of the DGF. Communication 150 German standard methods for study of fats, fatty products, surfactants and related materials. Communication 116 Analysis of surface active materials XXV (in German), Fett Wiss. TechnoL, 1995, 97,468-470. Schwarz, G., P. Leenders, U. Ploog, Condensation products of fatty acids or their methyl esters with aminoethylethanolamine (in German), Fette, Seifen, Anstrichm., 1979,81, 154-158. Takano, S., K. Tsuji, Structural analysis of the amphoteric surfactants obtained by the reaction of l-(2-hydroxyethyl)-2-alkyl-2-imidazoline with ethyl acrylate,/. Am. Oil Chem. Soc., 1983, 60,1798-1806. 

AE, NPE, acid ethoxylates, amine ethoxylates, esters, ethoxylated esters, alkanolamides, ethoxylated alkanolamides, EO/PO copolymers LAS, alkyl sulfates, ether sulfates, isethionates, sulfosuccinate half ester, carboxylates, sarcosides, taurides, fatty acid alkanolamides, amine oxides, quaternary amines, betaines, imidazoline derivatives detection in personal care formulations... 

Ester quat—Quaternized tallow triethanolamine esters unquater-nized mono-, di-, and triesteramine impurities and fatty acid impurities separated triester-quat, diesterquat, and monoester-quat resolved elution according to decreasing alkyl character Distearyldimethylammonium chloride, cocoalkyldimethylbenzylam-monium chloride, cetyltrimethylammonium bromide, and a quaternary imidazoline compound resolved from J S V S ier environmental analysis... 

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