Method for producing chloroformyl-functional organopolysiloxane

Abstract: There is disclosed an organopolysiloxane having a molecular weight of 200 to 100,000 which contains at least one silicon-bonded, chloroformyl group-containing organic group, said organopolysiloxane being prepared by reacting (I) the corresponding organopolysiloxane which contains at least one silicon-bonded, triorganosiloxycarbonyl group-containing organic group; and (II) an inorganic halide, such as thionyl chloride. By virtue of its highly reactive chloroformyl group, the organopolysiloxane of the invention find utility as modifiers for polyamide resins, polyester resins, and the like.

Description: The present invention relates to a novel organopolysiloxane, and, more particularly, relates both to an organopolysiloxane whose molecule contains at least one silicon-bonded, chloroformyl group-containing organic group as well as to a method for the preparation of same. Organofunctional group-containing organopolysiloxane is employed as a modifier of organic resins through the former's copolymerization with organic resin monomer. This serves to endow the particular organic resin with the weather resistance, surface water repellency, lubricity, biocompatibility, and gas permeability, which are characteristic of the organopolysiloxanes. Chloroformyl group-containing organic compounds are generally prepared by the reaction of inorganic halide (for example, thionyl chloride) with organic carboxylic acid. Hydrochloric acid, a protonic acid, is generated as a by-product in this case. When this method is applied to carboxylic acid-modified organopolysiloxane, the silicon-oxygen bond, which has a high degree of ionic bond character, is attacked by the protonic acid, and secondary reactions occur in the form of siloxane bond scission, rearrangement, and redistribution. This makes it impossible to obtain the desired organopolysiloxane carrying the Si-bonded, chloroformyl group-containing organic group in its molecular chain. In another approach, an addition reaction was attempted between chloroformyl-substituted unsaturated hydrocarbon and SiH-containing organopolysiloxane in the presence of a Group VIII transition metal complex catalyst, but this addition reaction did not in fact proceed and the desired organopolysiloxane carrying the Si-bonded, chloroformyl group-containing organic group in its molecular chain was not obtained. GB-A 2 213 493 discloses a method for making silylaroylhalides such as chlorodimethylsilylbenzoyl chloride. These compounds are prepared by reacting equivalent amounts of a polyhaloacyl aromatic compound and a polyhalopolysilane in the presence of a palladium catalyst. In view of the preceding, the present inventor carried out extensive research which was directed toward the development of organopolysiloxane whose molecule contains at least 1 Si-bonded, chloroformyl group-containing organic group, as well as toward the development of a method for the preparation of same. They discovered as a result that the reaction of inorganic halide (for example, thionyl chloride) with organopolysiloxane whose molecular chain contains the Si-bonded, triorganosiloxycarbonyl group-containing organic group, results in conversion of the triorganosilylcarbonyl group into the chloroformyl group. It was also discovered that siloxane bond scission does not occur under these conditions since the by-product in this case is a triorganochlorosilane, which is not a protonic acid. The present invention takes as its object the preparation of an organopolysiloxane whose molecular chain contains a silicon-bonded, chloroformyl group-containing organic group, which is highly reactive with organic resin monomers, for use in the modification of organic resins. The present invention therefore relates to a method for preparing an organopolysiloxane having at least one silicon-bonded, chloroformyl group-containing organic group, characterized by reacting (I) an organopolysiloxane having a molecular weight of 200 to 100,000 which contains at least one silicon-bonded, triorganosiloxycarbonyl group-containing organic group; and (II) an inorganic chloride. To explain the preceding in greater detail, each molecule of the organopolysiloxane obtained with the method of the present invention must contain at least one silicon-bonded, chloroformyl group-containing organic group, that is, a group represented by the following general formula -A-COCl wherein A is a divalent organic group, which is exemplified by alkylene groups, such as ethylene, propylene, and butylene, and by alkyleneoxyalkylene groups such as propyleneoxypropylene and propyleneoxypentylene. Other than the chloroformyl-containing organi group(s), the organic groups in the organopolysiloxane obtained with the method of the present invention are exemplified by alkyl groups such as methyl, ethyl, propyl, butyl, pentyl and hexyl; by aryl groups such as phenyl, tolyl and xylyl ; and by aralkyl groups such as benzyl and phenethyl. The present invention's organopolysiloxane should have a molecular weight of 200 to 100,000 for the following reasons. When its molecular weight falls below 200, the organopolysiloxane evidences only an unsatisfactory capacity for modifying organic resins; when its molecular weight exceeds 100,000, the compatibility with organic resin monomer declines and the copolymerizability with organic resin monomer diminishes. Organopolysiloxane is readily prepared according to the present invention by the reaction of inorganic chloride with organopolysiloxane whose molecule contains at least one silicon-bonded, triorganosiloxycarbonyl group-containing organic group. Thus, the present invention makes use of organopolysiloxane whose molecule contains at least one silicon-bonded, triorganosiloxycarbonyl group-containing organic group as represented by the following general formula ≡Si-A-COOSiR 3 In the preceding formula, A is the divalent organic group described above, while R is a monovalent organic group as exemplified by alkyl groups, such as methyl, ethyl, and propyl, and by aryl groups, such as phenyl, and tolyl. This organopolysiloxane is reacted with an inorganic halide to afford the present invention's organopolysiloxane whose molecule contains at least one silicon-bonded, chloroformyl group-containing organic group. The aforesaid organopolysiloxane whose molecule contains at least one silicon-bonded, triorganosiloxycarbonyl group-containing organic group may be synthesized by an addition reaction between SiH-containing organopolysiloxane and triorganosiloxycarbonyl group-containing unsaturated hydrocarbon in the presence of a Group VIII transition metal complex catalyst. Inorganic chlorides which may be deployed within the context of the present invention are exemplified by phosphoryl chloride, thionyl chloride, phosphorus pentachloride, and phosphorus trichloride, inter alia. The skilled artisan will readily select those inorganic chlorides which will operate in the method of the present invention based on experience with the corresponding organic reaction. Among these, thionyl chloride is preferred because of its low boiling point and the fact that the reaction by-products are gaseous or low-boiling substances which serve to facilitate product isolation. With regard to the reaction between inorganic chloride and organopolysiloxane whose molecule contains at least 1 silicon-bonded, triorganosiloxycarbonyl group-containing organic group, this reaction should be carried out using at least 1 equivalent, but preferably using at least 5 equivalents, of the former per equivalent of the latter. While this reaction is preferably carried out without the use of solvent, it may be conducted in the presence of solvent. Examples of the solvent are aromatic solvents, such as benzene, toluene, and xylene, and aliphatic solvents, such as hexane and heptane. This reaction may be run at room temperature, but implementation at temperatures of 50 to 200 degrees Centigrade will be advantageous in terms of the reaction rate. The present invention is explained in greater detail through the following illustrative examples, but is not restricted thereby. In these examples, Me denotes a methyl radical and n-Bu denotes a n-butyl radical. Comparison Example 1 The following were charged to a stirrer-equipped four-neck flask and heated with stirring for 3 hours at 80 degrees Centigrade: 6.56 grams (55.2 millimoles) thionyl chloride and 9.6 grams (5.52 millimoles) of an organopolysiloxane represented by the average formula This organopolysiloxane had a molecular weight distribution = 1.19 according to gel permeation chromatography (GPC). After confirmation of the disappearance of the absorption characteristic of carboxylic acid by infrared absorption spectroscopic analysis (IR), 9.7 grams of product was recovered by distillation of low-boiling components by heating in vacuo. This product was confirmed by nuclear magnetic resonance analysis (NMR) and IR to be an organopolysiloxane with the following average formula The following were mixed and stirred overnight at room temperature: 7 grams (3.98 millimoles) of the organopolysiloxane prepared above, 1.27 grams (39.8 millimoles) methanol, 0.81 grams (7.96 millimoles) triethylamine, and 20 milliliters toluene. The salt by-product was removed by filtration, and 5.1 grams product was recovered by distillation of the low-boiling components by heating in vacuo. This product was confirmed by NMR and IR to be organopolysiloxane with the following average formula However, this organopolysiloxane had a GPC-based molecular weight distribution of 1.7, which confirmed the occurrence of siloxane bond scission as well as rearrangement and redistribution during the chloroformylation reaction. Comparison Example 2 The following were charged to a stirrer-equipped four-neck flask: 12.56 grams (79.88 millimoles) unsaturated carboxylic acid chloride as represented by the following formula CH 2 =CHCH 2 OCH 2 CH 2 COCl 32.96 grams (79.87 millimoles) oligosiloxane as represented by the following formula and platinum/tetramethyldivinylsiloxane complex in a quantity sufficient to provide 200 ppm platinum metal referred to the total quantity of the first two reactants. After stirring for 10.5 hours with heating to 90 degrees Centigrade and then sampling, disappearance of the starting acid chloride was confirmed by gas/liquid chromatography (GLC). The major product was isolated by distillation in vacuo. Investigation by NMR and IR could not confirm the production of but t he production of was confirmed. Example 1 Thionyl chloride (8.96 grams; 75.35 millimoles) and 10 grams (15.94 millimoles) oligosiloxane with the following formula were introduced into a stirrer-equipped four-neck flask. After stirring for 1 hour with heating at 60 degrees Centigrade, disappearance of the starting oligosiloxane was confirmed by GLC, and 8.6 grams product was recovered by distillation of the low-boiling components by heating in vacuo. This was confirmed by NMR and IR to have the following formula Example 2 Twelve grams (20.94 millimoles) of an oligosiloxane having the structure and 12.48 grams (104.86 millimoles) thionyl chloride were introduced into a stirrer-equipped four-neck flask. Upon stirring for 3 hours at 75 degrees Centigrade, disappearance of the absorption characteristic of trimethylsilyl carboxylate was confirmed by IR. The product (7.1 grams) was recovered by distillation in vacuo. This was confirmed by NMR and IR to have the following formula Example 3 The following were charged to a stirrer-equipped four-neck flask and stirred for 3 hours with heating at 80 degrees Centigrade: 10 grams (5.52 millimoles) organopolysiloxane (molecular weight distribution by GPC = 1.17) with the following average formula and 6.56 grams (55.2 millimoles) thionyl chloride. The disappearance of the absorption characteristic of trimethylsilyl carboxylate was confirmed by IR, and 9.7 grams product was recovered by distillation of the low-boiling components by heating in vacuo. This product was confirmed by NMR and IR to be an organopolysiloxane with the following average formula Seven grams (3.98 millimoles) of this organopolysiloxane, 1.27 grams (39.8 millimoles) methanol, 0.81 grams (7.96 millimoles) triethylamine, and 20 milliliters toluene were mixed and stirred overnight at room temperature. The salt by-product was removed by filtration, and 5.1 grams product was obtained by distillation of the low-boiling components by heating in vacuo. This product was confirmed by NMR and IR to be an organopolysiloxane with the following average formula The molecular weight distribution of this organopolysiloxane was 1.16 by GPC, which thus confirmed the complete absence of siloxane bond scission and rearrangement/redistribution during the chloroformylation reaction. Example 4 The following were placed in a stirrer-equipped four-neck flask and reacted by heating for 8 hours at 75 degrees Centigrade: 12 grams (23.30 millimoles) oligosiloxane with the following formula and 13.86 grams (116.49 millimoles) thionyl chloride. After standing overnight, disappearance of the absorption characteristic of trimethylsilyl carboxylate ester was confirmed by IR, and 6.7 grams product was recovered by distillation in vacuo. This product was confirmed by NMR and IR to have the following structure Example 5 The following were placed in a stirrer-equipped four-neck flask and stirred for 3.5 hours while heating to 75 degrees Centigrade: 10 grams (15.45 millimoles) oligosiloxane with the following formula and 9.19 grams (77.25 millimoles) thionyl chloride. Disappearance of the absorption characteristic of trimethylsilyl carboxylate was confirmed by IR, and 7.8 grams product was recovered by distillation of the low-boiling components by heating in vacuo. This product was confirmed by NMR and IR to have the following formula

Claims: A method for preparing an organopolysiloxane having at least one silicon-bonded, chloroformyl group-containing organic group, characterized by reacting (I) an organopolysiloxane having a molecular weight of 200 to 100,000 which contains at least one silicon-bonded, triorganosiloxycarbonyl group-containing organic group; and (II) an inorganic chloride.

Inventors: TADASHI OKAWA, TADASHI, OKAWA
Applicants: DOW CORNING TORAY SILICONE, DOW CORNING TORAY SILICONE COMPANY, LIMITED
Application year: 1991
Main classification: C08G77
IPC codes: C08G77