Overview[1]
Phase transfer catalysis technology began in 1965, and the concept of “phase transfer catalysis” was introduced in 1968. After more than two decades of development, this technology has been widely used in organic synthesis.
Benzyltriethylammonium chloride is a quaternary ammonium salt phase transfer catalyst with outstanding features such as easy availability of raw materials, simple synthesis, and low cost. In recent years, benzyltriethylammonium chloride has been widely used in organic synthesis reactions, especially in two-phase reactions of water and organic solvents. It is characterized by fast reaction speed, high yield, easy operation, and low toxicity. , so it is mostly used in nucleophilic substitution, carbene reaction, C-alkylation, N-alkylation, O-alkylation, S-alkylation and other reactions.
Preparation method[2]
There are many preparation methods for benzyltriethylammonium chloride, but they all use triethylamine and benzyl chloride as raw materials, mainly including:
1. Ethanol solvent method
Place 50.0 g (0.40 mol) benzyl chloride and 33.7 g (o.33 mol) triethylamine in 60 ml absolute ethanol and reflux for 64 h, cool to room temperature, and add 300 ml ether to precipitate the ammonium salt. Filter, redissolve the ammonium salt in a small amount of hot acetone, add ether and settle again to obtain a high purity product.
2. Dimethylformamide solvent method
Place 346.5g triethylamine, 413.5g benzyl chloride and ethyl acetate in 238.6g dimethylformamide (DMF) and reflux for 1 hour. Add 300g benzene at 80°C to settle the ammonium salt. Filter with suction, wash with benzene, and dry in vacuum to obtain 648g of product with a purity of 98.1%.
3. Dichloroethane solvent method
Place 23g triethylamine and 30g benzyl chloride in 120g dichloroethane and reflux for 2 hours to obtain 52.6g product benzyltriethylammonium chloride.
4. Water solvent method
Mix benzyl chloride and triethylamine in a ratio of 1:1.2 (mo1 ratio), stir and reflux for 10 hours. The triethylamine used is a 50-60% aqueous solution. After the reaction is completed, a transparent TEBA aqueous solution is obtained, with a content of about 60% and a yield of 75 to 85%. Benzyltriethylammonium chloride can be directly used as a catalyst.
5. Solvent-free method
Mix benzyl chloride and triethylamine in a ratio of 1:1.3 (mol ratio) thoroughly, put it into a ground-mouth Erlenmeyer flask, cover it with a stopper, and let it stand for 60 hours before it turns into a solid. After recrystallization with petroleum ether, white pure benzyltriethylammonium chloride is obtained.
Apply[2]
Benzyltriethylammonium chloride is a commonly used quaternary ammonium salt phase transfer catalyst. It can improve reaction conditions, increase yields, and enable reactions that cannot proceed under normal conditions to proceed normally. It has a very wide range of applications in the field of organic synthesis. application. Phase transfer catalysts were initially used for nucleophilic substitution reactions, and later developed for various types of reactions such as oxidation, peroxidation, and reduction. They are used in pesticides, spices, photographic materials, medicine, plastics and other fields.
Benzyltriethylammonium chloride has the ability to dissolve in both the aqueous phase and the organic phase. The positive and negative ions in the quaternary ammonium salt form ion pairs in the aqueous phase, which can transfer the negative ions from the aqueous phase to the organic phase. In the organic phase, negative ions have no solvation effect, and because the positive ions are large in size, the distance between positive and negative ions is also large, and the interaction between positive and negative ions is weak. The negative ions can be regarded as naked, so the reaction activity is greatly improved. Therefore, benzyltriethylammonium chloride can be used as a phase transfer catalyst in organic synthesis, a curing accelerator for polymer polymerization, an organic electrolyte in the electronics industry, an oil field chemical agent, a molecular sieve template agent, a phase change cold storage material, and a high-performance liquid chromatography Analytical reagents, surfactants, detergents, adsorbents, oil displacing agents, etc.; curing accelerators for polymer polymerization of powder coatings, epoxy resins, etc.
Reference materials
[1]Zhao Lun, Deng Qinghui, Wu Zhizheng, et al. Benzyl Triethyl Ammonium Chloride as Phase Transfer Catalyzed Synthesis of 4,4′-Triethyl Ammonium Chloride as Phase Transfer Catalyst ,4′-(phenylazanediyl)dibenzoic Acid[J]. Journal of Changchun Normal University (Natural Science Edition), 2014, 000(003):82-84.
[2] Preparation of benzyltriethylammonium chloride and its application in organic synthesis Cao Guanghong Liaoning Chemical Industry 1991 (5), 16-19, 42
