O. Yu. Grigor’eva

Acyl iodides in organic synthesis. Reactions of acetyl iodide with urea, thiourea, and their N,N′-disubstituted derivatives

Acetyl iodide reacted with urea and its derivatives to give the corresponding N-substituted products. The reactions of acetyl iodide with thiourea, N,N′-dimethylthiourea, imidazolidine-2-thione, and hexahydropyrimidine-2-thione resulted in the formation of S- or N-acetyl derivatives, depending on the temperature and structure of the sulfur functionality (thione or thiol). By contrast, in the reaction of acetyl iodide with N,N′-bis(3-triethoxysilylpropyl)thiourea one ethoxy group on the silicon atom was replaced by iodine with formation of N-{3-[(diethoxy)iodosilyl]propyl}-N′-[3-(triethoxysilyl)propyl]thiourea. The latter decomposed on heating to give 3-triethoxysilylpropyl isothiocyanate and silicon-containing polymer with the composition C45H97IN6O14.5S3Si6.

Reaction of carboxylic acids with tetrachlorosilane

Tetrachlorosilane reacted with carboxylic acids RCOOH (R = Me, Bu, t-Bu) to give the corresponding acid chlorides RCOCl in 75–95% yield. The reactions of SiCl4 with trichloroacetic and 2-fluorobenzoic acids (R = Cl3C, 2-FC6H4) occurred more difficultly, presumably for steric reasons, and the yields of the corresponding acid chlorides were 11 and 22%, respectively. Tetrachlorosilane failed to react with stearic acid under analogous conditions. Products of the reactions of SiCl4 with chloroacetic and benzoic acids RCOOH (R = ClCH2, Ph) were tetraacyloxysilanes Si(OCOR)4, and tetrakis(chloroacetoxy)silane was formed in almost quantitative yield. The reaction of SiCl4 with glutaric acid led to the formation of a rubber-like polymeric material with the composition C5H6Cl2O4Si. The effect of pKa values of carboxylic acids on the direction and mechanism of the examined reaction is discussed.

Acyl iodides in organic synthesis: XII. Reactions with organosilicon amines

Reactions were investigated between acyl iodides RCOI (R = Me, Ph) and organosilicon amines of two classes: trimethyl(diethylamino)silane, dimethyl-bis(diethylamino)silane, and hexamethyldisilazane on the one hand, and 3-aminopropyl(triorganyl)silanes H2N(CH2)3SiX3 (X = Et, EtO) on the other hand. The reaction of RCOI with trimethyl(diethylamino)silane Me3SiNEt2 occurred with a cleavage of the Si-N bond and the formation of N,N-diethylacet- or -benzamides and trimethyliodosilane separated in a mixture with hexamethyldisiloxane. At the reaction of acyl iodides RCOI (R = Me, Ph) with dimethyl-bis(diethylamino)silane in the ratio 2:1 in benzene solution both Si-N were ruptured leading to the diethylamide of the corresponding acid and dimethyldiiodosilane. The main product of the reaction of acetyl iodide with hexamethyldisilazane at the molar ratio 2:1 was diacetylimide (MeCO)2NH. This reaction can be recommended as a simple and convenient preparation procedure for diacylimides. The exothermal reaction of the acetyl iodide with 3-aminopropyl(triethyl)- and -(triethoxy)silanes at the molar ratio of the reagents 1:1 without solvent resulted in quaternary ammonium salts, hydroiodides of the corresponding acetylamides I−MeCON+H2(CH2)3SiX3 (X = Et, OEt).

Acyl iodides in organic synthesis. reaction of acetyl iodide with Dialkyl sulfides and disulfides

Reactions of acetyl iodide with dialkyl and dialkenyl sulfides RSR (R = Et, Bu, CH2=CH, CH2=CHCH2) and with disulfides RSSR (R = Pr, C6H13, PhCH2) were studied. Dialkyl sulfides reacted with MeCOI to give the corresponding alkyl ethanethioates and alkyl iodides as a result of cleavage of the S-C bond. The reactions of acetyl iodide with divinyl and diallyl sulfides involved addition across the double bond and subsequent polymerization of 1-alkenylsulfanyl-2(3)-iodoalkyl methyl ketones. Dialkyl disulfides RSSR (R = Pr, C6H13) and dibenzyl disulfide reacted with acetyl iodide via cleavage of the S-S bond to produce the corresponding ethanethioates and organylsulfenyl iodides. The latter underwent disproportionation to form the initial disulfide and molecular iodine.

Expected and unexpected photochemical reactions of acyl iodides

Photolysis of acyl iodides RCOI (R = Me, Me2CH, Ph) under UV irradiation in toluene environment for 20–55 h proved to be a simple and efficient method of preparation of symmetrical α-diketones RCOCOR. In contrast, the photolysis under the same conditions of acyl iodides RCOI [R = Me(CH2)3, Me3C] did not lead to the formation of the corresponding diacyls, and the reaction products were unexpected 1,1-bis(4-methylphenyl)pentane and a mixture of isomeric 3- and 4-methyl(tert-butyl)benzenes respectively. The most probable mechanism of their formation is the primary photochemical acylation of toluene in the aromatic ring followed by the photochemical reduction of the arising butyl 4-methylphenyl ketone in the case of the valeroyl iodide or the photochemical Norrish type I cleavage of isomeric 3- and 4-methylphenyl (tert-butyl) ketones in event of the pivaloyl iodide. In the photolysis of acetyl iodide (R = Me) in benzene or toluene alongside the diacetyl formation polyarylation process was observed of acylated and iodinated into the aromatic ring solvents with the formation of polymeric products with semiconductor and paramagnetic properties.

Reactions of acetyl iodide with triethylsilylalkyl propyl sulfides

Triethylsilylmethyl propyl sulfide was synthesized by reacting chloromethyl(triethyl)silane with sodium propanethiolate [2]. In contrast, the reaction of triethylsilylethyl propyl sulfide (n = 2) with acetyl iodide affords unexpectedly hexaethoxydisiloxane as one of the reaction products. Triethylsilylethyl ethanethioate was not found in the reaction mixture, but the formation of propyl ethanethioate was detected. This indicates that in the case of β-configuration of silicon and sulfur heteroatoms (n = 2) the bond between the sulfur atom and β-located carbon atom is cleaved to form propyl ethanethioate and triethylsilylethyl iodide. Under the reaction conditions the latter undergoes β-cleavage, which is characteristic for the β-halogenated organosilicon compounds [3]. Hydrolytic condensation of the product of this cleavage, iodotriethylsilane, occurs easily even under the influence of air moisture to give hexaethyldisiloxane. DOI: 10.1134/S1070363213100290

Acyl iodides in organic synthesis. Reaction of acetyl iodide with thiols

The direction of reactions of acetyl iodide with aliphatic, aromatic, and heterocyclic thiols is determined by the thiol acidity and steric factors. Acetyl iodide reacted with aliphatic thiols, including trialkylsilylsubstituted derivatives R(CH2)nSH (R = Me, n = 3; R = Me3Si, n = 3; R = Et3Si, n = 2), to give the corresponding ethanethioates R(CH2)nSCOMe. Benzenethiol was oxidized with acetyl iodide to diphenyl disulfide. The reaction of acetyl iodide with 2-sulfanylethanol afforded 2-(2-iodoethyldisulfanyl)ethyl acetate as a result of three consecutive-parallel processes: acylation, iodination, and oxidation of the initial compound. 1,3-Benzothiazole-2-thiol reacted with acetyl iodide only at the nitrogen atom to give quaternary salt, whereas the SH group remained intact.

Organosilicon compounds containing carbofunctional biguanidine group

The reaction of triethoxysilylpropylamine (AGM-9) with dicyanodiamide was studied. The condensation of AGM-9 with dicyanodiamide occurs in the presence of a catalytic amount of CuCl2 at 125–145°C within 5–24 h; it involves both the amino group of AGM-9 and ethoxy substituents at the Si atoms, with an unusual exchange of a Si-O bond for a Si-N bond. The final reaction product is 1-N-(3-triethoxysilylpropyl)-2-N-[3-aminopropylsilyl(diethoxy)]biguanidine. Its hydrolytic polycondensation yields an organosilicon polymer, a polycondensate of AGM-9 with 1-N-(3-triethoxysilylpropyl)biguanidine, which is a highly efficient sorbent for Ag(I) (static sorption capacity 544 mg g−1).

Reaction of Dioxides Derived from Organosilicon Thiocarbamides with Ammonia and Methylamine

Reactions of organosilicon thiocarbamide dioxides {[R3Si(CH2)3NH]2CSO2, R = Et (I), O1.5 (II)} with methylamine and ammonia were studied. The reaction of compound I with ammonia involves, along with the substitution of the NHC(SO2)NH fragment by a guanidine residue, Si-C bond cleavage to form an oligomer comprising [O(Et)Si(CH2)3NH]2C=NH and [O1.5Si(CH2)3NH]2C=NH elementary units. The reactions of compound II with methylamine and ammonia resulted in the synthesis of organosilicon polymers containing guanidine groups. These polymers exhibit a high sorption capacity toward Ag(I).

Reaction of acetyl iodide with dialkyl sulfoxides

We previously showed that reactions of acetyl iodide with dialkyl sulfides involve cleavage of the C–S bond in the latter with formation of ethanethioates and alkyl iodides [1]. Likewise, C–S bond cleavage was observed in the reactions of acetyl iodide with silylalkyl sulfides Et3Si(CH2)nSPr (n = 1, 2), but the product structure depended on the mutual position of the sulfur and silicon atoms [2]. We now report on the chemical behavior of acetyl iodide in reactions with dialkyl sulfoxides.