Ethyleneimines

Acetic acid Chromium(VI) oxide, chlorosulfonic acid, ethylene glycol, ethyleneimine, hydroxyl compounds, nitric acid, oleum, perchloric acid, peroxides, permanganates, potasssium r rf-butoxide, PCI3... 

Hydrogen fluoride Acetic anhydride, 2-aminoethanol, ammonia, arsenic trioxide, chlorosulfonic acid, ethylenediamine, ethyleneimine, fluorine, HgO, oleum, phosphorus trioxide, propylene oxide, sodium, sulfuric acid, vinyl acetate... 

Silver Acetylene, ammonium compounds, ethyleneimine, hydrogen peroxide, oxalic acid, sulfuric acid, tartaric acid... 

Other reactions that show preference for the acidic N-3—H group include Mannich aminomethylation by treatment with formaldehyde and an amine (38) to yield compound (8), reaction with ethyleneimine (39) to give (9), and Michael-type additions (40) such as the one with acrylonitrile to give (10) ... 

Ethyleneimine (El) and its two most important derivatives, 2-methyla2iridine [75-55-8] (propyleneimine) (PI) and l-(2-hydroxyethyl)a2iridine [1072-52-2] (HEA) are colodess Hquids. They are miscible ia all proportions with water and the majority of organic solvents. Ethyleneimine is not miscible with concentrated aqueous NaOH solutions (>17% by weight) (24). Ethyleneimine has an odor similar to ammonia and is detectable only at concentrations >2 ppm. The physical properties of ethyleneimine and the derivatives mentioned are given ia Table 1. Thermodynamic data can be found ia the Hterature (32). 

Unlike the other stmctural isomers of C2H N, /V-methylenemethylamine (33,34), ethylideneimine (35), and vinylamine [593-67-9] (36,37) and the analogous phosphoms compound, phosphirane (38), ethyleneimine is stable at room temperature provided CO2 is excluded from the air (39). Unexpectedly, ethyleneimine has the highest calculated relative heat of formation of the C2H N isomers (40). Relative calculated heats of formation are ethylideneimine. 

Nucleophilic Ring Opening. Opening of the ethyleneimine ring with acid catalysis can generally be accompHshed by the formation of an iatermediate ayiridinium salt, with subsequent nucleophilic substitution on the carbon atom which loses the amino group. In the foUowiag, R represents a Lewis acid, usually A = the nucleophile. 

Because of the rapid ring opening by the nucleophile, ayiridinium salts cannot usually be isolated. However, in a few cases it is possible to isolate such compounds (54), eg, at low temperatures, when the ayiridinium salts ate sparingly soluble or where there is steric hindrance to substitution. Stable ethyleneiminium salts can be prepared by reaction of ethyleneimine with acids not containing nucleophilic anions, for example HBF (55). 

Reaction with Sulfur Nucleophiles, Because sulfai is highly nucleophilic, reactions of aziridines with sulfur nucleophiles generally proceed rapidly (111) and with good yields. The reaction of hydrogen sulfide [7783-06S-J with ethyleneimine yields cysteamine [60-23-1] (2-mercaptoethylamine) or bis(2-aminoethyl)sulfide [871-76-1] (2,112) depending on the molar ratio of the reactants. The use of NaHS for the synthesis of cysteamine has also been described (113). 

The di- or tettahydto-l,4-thiazine skeleton is obtained if mercaptans which have a carbonyl group in the P-position react with ethyleneimine (120—124)... 

The reaction of thioethers with ethyleneimine in the presence of acid yields sulfonium compounds. The reaction is reversible under alkaline conditions (125). Compounds in which double-bonded sulfur can exist in tautomerism with a form having a free SH group, such as thiourea (126,127), thiocarboxyhc acids (128), and thiophosphates (129), react to give aminoaLkylated products. The P-aminoethyl thiocarboxylate rearranges to give the amide. 

Ethyleneimine reacts rapidly with sulfurous acid to give taurine [107-35-7] in high yield, a reaction of importance not only for the preparation of this amino sulfonic acid but also for the decontamination of ethyleneimine solutions (130). 

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