1.Overview

Amphoteric surfactants refer to both cationic hydrophilic groups and anionic hydrophobic groups in the molecular structure, which can be ionized in an aqueous solution and exhibit the characteristics of anionic surfactants under a certain medium condition, but under another medium condition It is a class of surfactants that exhibit the characteristics of cationic surfactants.

Betaine-type amphoteric surfactants refer to a class of compounds whose structure is similar to that of natural product betaine. The chemical name of betaine is trimethylammonium acetate. It is a natural product discovered by Scheibler (Scheibler C. 1869, Scheibler C. 1870) and separated from beet juice. Scheibler named betaine beta-in after its Latin name beta vulgaris.

In 1876, Bruhl adopted the term betaine and suggested that compounds with similar structures as natural products be named “betaines“, which are betaine-type amphoteric surfactants. Betaine type amphoteric surfactants can be divided into carboxylic acid type, sulfonic acid type, sulfate type, sulfite type, phosphate type, phosphite type, phosphonic acid type and phosphonite type according to the type of acid group. . At present, domestic researches on betaine surfactants are very active. Among them, carboxylic acid type, sulfonic acid type and phosphate type products have been reported more.

Most of the positive charge centers of betaine-type amphoteric surfactants are supported on quaternary ammonium N atoms, while the negative charge centers are supported on negatively charged acid groups. The difference between betaine-type amphoteric surfactants and other amphoteric surfactants is that due to the presence of quaternary ammonium nitrogen in the molecule, it will not exist in the form of anionic surfactants in alkaline solutions. In different pH ranges, betaine-type amphoteric surfactants will only exist in the form of zwitterionic or cationic surfactants. Therefore, in the isoelectric zone, betaine amphoteric surfactants are not as prone to a sharp decrease in solubility like other amphoteric surfactants with weakly basic nitrogen.

Betaine type amphoteric surfactants are also different from cationic surfactants. Some researchers (Beckett AH 1963) believe that it should be classified as a “quaternary ammonium salt amphoteric surfactant”; Moore CD (1960) believes that it should be classified as a “quaternary ammonium salt surfactant” . Unlike cationic surfactants such as “external quaternary ammonium salt surfactants”, betaine-type amphoteric surfactants can be used in combination with anionic surfactants and will not form “electrically neutral” compounds.

Betaine-type amphoteric surfactants are an important part of amphoteric surfactants. It has excellent compatibility with anionic, cationic and nonionic surfactants, has excellent synergistic effects, and is mild in nature. It has good antistatic properties, bactericidal properties, anticorrosive properties, and is easily biodegradable. It is widely used in the daily chemical industry. With the deepening of research, more betaine-type surfactants will be developed and applied.

2. Research progress of betaine-type amphoteric surfactants

As early as 1869, Liebreich O. used trimethylamine to prepare betaine; in 1937, the first patent report of amphoteric surfactants appeared in the United Kingdom, and in 1940 DuPont reported the first betaine series (Betaine) amphoteric surfactants. Since then, various countries have begun to research and develop amphoteric surfactants including betaine compounds. With the increasing application of betaine surfactants, the pace of research in this field is also accelerating. In recent years, many new products have been developed.

Xu Jinyun et al. prepared octadecyl betaine with octadecyl tertiary amine, chloroacetic acid, and sodium hydroxide as raw materials, and tested its surface tension, antistatic properties, emulsifying properties and other application properties. Base betaine was compared. Zhang Li and others have also done some research on the interface chemistry of this surfactant, such as surface tension, microemulsion and structural parameters.

Chen Zonggang and others reacted with stearic acid and triethanolamine to generate triethanolamine stearate, and controlled the ratio of the reactants to make the product mainly a diester, and then reacted with the quaternization reagent sodium monochloroacetate to generate triethanolamine fatty acid ester Betaine. This surfactant can be used as a softening agent for printing and dyeing. Its softness is close to amino silicone oil, its whiteness and wettability are better than amino silicone oil, and it is easily biodegradable. It is an environmentally friendly product.

FangYiwen etal. synthesized lauroamidopropyl betaine with N,N-dimethyl N’-lauroyl-1,3-propanediamine and sodium chloroacetate as raw materials. The product has high foaming, foam stabilization and thickening properties. , Good compatibility with other components in shampoo.

Chen Hongling et al. synthesized two sulfoimidazoline betaines using sodium 2-bromoethyl sulfonate as the hydrophilic base material and alkyl imidazoline and tested their physical and chemical properties. The structural formula is as follows.

Jiang Liubo obtains N-lauricamidopropyl-N’-β-hydroxypropylamine sulfobetaine by removing sodium chloride from sodium l-chloropropyl-2-hydroxysulfonate and lauramide dimethylpropylamine through reaction, each The technical indicators are basically in line with imported brand-name products. It has mild performance, very low irritation, rich and fine foam, and excellent water resistance and sterilization.

Nonglanping uses dodecanol, epichlorohydrin, chloroethanol and dimethylamine as raw materials, and P2O5 as phosphorylation reagent, and the synthetic name is 2-[N-(3-dodecyloxy-2-hydroxy)propyl -N,N-Dimethylammonium] ethyl acid phosphate betaine.

 

Cen Bo et al. separated and purified dehydroabietylamine from disproportionated rosin amine, and then synthesized N-dehydroabietyl-N through N,N-dimethyl dehydroabietyl amine as a raw material. N-dimethyl carboxymethyl betaine and its chloride are two new type of betaine amphoteric surfactants.

 

Wang Jun et al. synthesized the betaine type amphoteric surfactant-dodecyl dimethyl hydroxypropyl sulfobetaine with epichlorohydrin, sodium bisulfite and tertiary dodecyl amine as raw materials, The reaction conditions were optimized.

 

Henan Dao Chung Chemical Technology Co., Ltd. has prepared two new betaine-type amphoteric surfactants containing polyoxyethylene chain structure by reacting alkyl polyoxyethylene dimethyl tertiary amine with chloroacetic acid or chloroethyl sulfuric acid. Realize industrialized production.

 

Foreign countries are still at the leading level in the field of betaine surfactants, and their research and development work deserves full attention and study reference. For example, Chew, CH, etc. synthesized a betaine-type surfactant polymer AUDMAA with acryloyl chloride 1-pyridinedecanol and aminoacetic acid. Its critical micelle concentration at 24℃ is 9.42×10-3mol/L. The polymerization activation energy is 50.2kJ/mol. Furuno Takeshi et al. synthesized two new betaine-type surfactants N,N-hydroxyethyl-N-ethyl fatty acid ester betaine and N-(fatty acid ester) ethyl- with tarot oil fatty acid as raw material. N,N-bis(2-hydroxyethyl)-3-12-hydroxypropyl)ammonium sulfonate.

 

In recent years, there have been many gratifying developments in the physical and chemical properties of betaine surfactants. For example: YousukeOne, etc. (dodecyl, tetradecyl, hexadecyl, oleic acid)-dimethyl betaine subject, the dielectric behavior of the micellar solution of betaine surfactant was studied. It has nothing to do with the concentration of micelles, and the relaxation strength of the amphoteric surfactant solution changes proportionally to the concentration, which is similar to the aminoglycolato betaine which has a betaine chemical structure but is not a surfactant. The results show that the micelle surface of the amphoteric surfactant also has the same instantaneous dipole moment as the glycine betaine solution.