Betaines and sulfobetaines

For zwitterionics of the betaine and sulfobetaine types, Ci2H25N+(CH3)2(CH2)m COO- and C12H25N+(CH3)2(CH2)3S03-, respectively, the micellar aggregation number varies very little with change in surfactant concentration or electrolyte content (Kamenka, 1995a). 

The binding of the counterions Na+ and Cl to zwitterionics of the betaine and sulfobetaine types starts well above the CMC and hence does not affect its value. The degree of binding of the Cl is always larger than that of the Na+ (Kamenka, 1995b). 

The tested amphoteric surfactants (betaine and sulfobetaine) are highly salt-tolerant and are excellent foamers. Adsorption of these surfactants is less dependent on salinity than adsorption of anionic surfactants, and the trends are not monotonic (Figure 13b). Adsorption of amphoteric surfactants may proceed by a complex interplay of mechanisms involving electrostatic and complexation mechanisms of both the cationic and the anionic group in the surfactant molecule (12, 87, 88). The trends in ad-... 

AEOs spiked into raw wastewaters were applied to elaborate an APCI or ESI-LC-MS method to determine non-ionic surfactants after SPE. Ionisation efficiencies of both interface types were compared and the more effective APCI technique then was applied for quantification [334]. Recoveries observed with standard determination methods for surfactants and MS detection techniques for different types of surfactants (e.g. alkylether carboxylates, sulfosuccinates, fatty acid polyglycol amines, quaternary carboxoalkyl ammonium compounds, modified AEOs, EO/ PO compounds, APGs, alkyl polyglucamides, betaine and sulfobetaine) in spiked wastewater samples were compared by applying APCI and/or ESI(-i-/-).Poor recoveries were obtained by standard methods but good results by MS [335]. APCI and... 

Betaines and sulfobetaines are also known for their foam-stabilizing effect [81]. 

These classifications represent the most fundamental members of this family of surfactants. It should be noted that the betaine and sulfobetaine surfactants discussed in the following section are in fact special members of classes 2 and 4. A number of additional structural modifications commonly encountered in commercial products add to the diversity of the materials and properties that can be obtained. 

Polyethers, alkanolamides, alkyls, alkylethoxylates, amines, benzyls, carbohydrates, esters, perfluoroalkyls Alkyl-, amidoimidazoline- and carboxy-quaternary ammonium salts Betaines, phosphobetaines, sulfobetaines... 

In contrast to this, there is little information available (11) on the thermodynamics of adsorption of alkyl betaines and no data on the thermodynamic parameters of adsorption or micellization for sulfobetaines. 

In the present work, we have synthesized two betaines and three sulfobetaines in very pure form and have determined their surface and thermodynamic properties of micellization and adsorption. From these data on the two classes of zwitterionics, energetics of micellization and adsorption of the hydrophilic head groups have been estimated and compared to those of nonionic surfactants. 

The molar absorptivities for the two betaines and the three sulfobetaines in aqueous solution are listed in Table I. Before being used for surface tension measurements, aqueous solution of surfactants were further purified by repeated passage (12) through minicolumns (SEP-PAK Cjs Cartridge, Waters Assoc., Milford Mass.) of octadecylsilanized silica gel. The concentration of surfactant in the effluent from these columns was determined by ultraviolet absorbance, using the molar absorptivities listed in Table I. 

Although the efficiencies of surface tension reduction, pCao, for the betaines and their corresponding sulfobetaines are almost the same, the former appear to show greater effectiveness in surface tenion reduction, as indicated by the values. This may be due... 

Zwitterionic surfactants, also known as amphoteric surfactants, have both cationic and anionic centers present in the same molecule. Generally, their properties are highly dependent on the pH of the solution. The cationic part is based on primary, secondary, or tertiary amines or quaternary ammonium cations. The anionic part can be more variable and include sulfonates, as in CHAPS (3-[(3-Cholamidopropyl)dimethylammonio]-l-propanesulfonate). Other anionic groups are sultaines illustrated by cocamidopropyl hydroxysultaine. Examples of zwitterionic surfactants include betaines (such as cocamidopropyl betaine, dodecyl betaine, lauramidopropyl betaine and cocoamido-2-hydroxypropyl sulfobetaine) and phosphates (such as lecithin). 

Sulfobetaines SB and CAS are similar to betaine B and CAPB except that sodium 3-chloro-2-hydroxy-propanesulfonate is the reactant in place of sodium chloroacetate. This material is prepared just prior to use from sodium bisulfite and epichlorohydrin (Fig. 9). All these betaine and sulfonbetaine reactions produce salt as a byproduct, which generally is just left in the product. Commercially, these products are sold as 30% to 40% aqueous solutions. 

DAHANAYAKE AND ROSEN Betaine, Sulfobetaine Synthesis, Properties 51... 

Snow, S.A., Fenton, W.N. and Owen, M.J. (1991) Zwitterionic organofunctional siloxanes as aqueous surfactants - synthesis and characterization of betaine functional siloxanes and their comparison to sulfobetaine functional siloxanes. Langmuir, 7(5), 868-71. 

Sulfobetaines are typically prepared by alkylsulfonation of a monomeric or polymeric tertiary amine with strained sultones, usually 1,3-propanesultone or 1,4-butanesultone. An alternative route is the reaction of tertiary amines with a haloalkylsulfonate. Most of the early investigations on polymeric betaines relate to the sulfo derivatives 23a-e, 24, 25, and 26 listed in Scheme 5 [1-4,178]. 

Thus far, only ionic micelles have been discussed, but some results were obtained for reactions in zwitterionic micelles of the betaine (Bl-12) and the sulfobetaine (SB3-16). These surfactants differ in that the carboxylate moiety of Bl-12 could react nucleophilically, and this behavior is observed in... 

Jarvis and Tong57 have recently reported on a new class of vinyl betaines prepared by allowing DBN to react with 2,3-diphenyIthiirene-1,1 -dioxide (103) I Eq. (30)1. The yellow betaine 104 prepared initially is oxidized to the colorless sulfobetaine 105 with m-chloroperbenzoic acid lEq. (30)1. 

Polymeric betaines or zwitterions are polyampholytes whose oppositely charged groups remote one from another are displaced on one pendant substituent. There are several types of monomers with a betaine structure carboxy-betaines, sulfobetaines and phosphobetaines. Poly-hT-ethyleneglycine (1), po-ly(N-3-sulfopropyl)-W-methacryloyloxyethyl-Nd -dimethylammonium betaine) (2) and poly[(2-methacryloyloxyethyl-2-(trimethylammonioethyl-phosphate)] (3) are typical examples of this kind of polyampholyte ... 

Amphoteric surfactants have especially good foaming profiles in soft water. Betaines, in particular the amidopropyl types, are tolerant of hard water, followed closely by the tolerance of sulfobetaines and... 

Polefka, in a patent assigned to Colgate, utilized cocamidopropyl betaine as a cationic-compatible surfactant in the preparation of another anti-plaque composition utilizing bisbiguanide as an antimicrobial active (115). Similar plaque control claims are made by Michaels, who describes a composition based on a blend of Cio-Cig alkyl A-sulfobetaine and Cio-Cig alkyl A,A-dihydroxylethylamine oxide (116). 

Sulfobetaines function similarly to betaines. They differ structurally in that the anionic site is a sulfate group in place of a carboxylate. They also differ in performance in that they are zwitterionic at aU pHs and are known to be extremely mild and provide a rich, creamy foam. 

Amphoteric surfactants are divided into two groups based on their response to pH. One class of compounds that contain carboxylated imidazoles and A-alkyl betaines are zwitterionic at pHs at, and above, their isoelectric points and cationic at lower pHs. Sulfobetaines and phosphobetaines, on the other hand, exhibit zwitterionic characteristics as the anionic portion is dissociated at all pHs. Although the former are the major ingredients in many baby shampoos or those products that provide mildness, they also function as foam and viscosity enhancers when utilized as secondary surfactants, having good water solubility over a wide pH range. ° ... 

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