The process according to claim 1 wherein said alcohol is a secondary alcohol selected from the group consisting of C. 10. Alternatively, dialkyltin dialkoxide catalysts may be synthesized adding urea product or the like and excess alcohol at a temperature in the range between about 155° C. to 190° C., preferably 155° C. to 170° C., and an autogenous pressure, wherein the alcohol converts the urea in-situ to an alkyl carbamate which then reacts with the excess alcohol to form the dialkyltin dialkoxide catalyst. The first step involves condensation of dibutyltin oxide with a primary alcohol in refluxing benzene or toluene at 80°-110° C., to produce 1,3-bis(alkoxy)tetrabutyl distannoxane.
Voronkov and Yu P. Romadan, New Method for the Synthesis of Dialkyoxydialkyltins, Zhurnal Obshchei Khimii, vol. Tel: +1 412-624-8727. In all cases the Ref. R 2 NC(O)Cl + R'OH → R 2 NCO 2 R' + HCl. 2785-2786, Dec. 1969.
8 Conducting the multicomponent reaction at a late stage in the synthetic sequence provides abundant …
Urea can also be added to the reactor for a continuous operation. Go to our 19. Carbamates also arise via alcoholysis of chloroformamides: . The dibutyltin oxide is present in an amount of about 1 to 25 mole %, based on the total reaction mixture. formally request permission using Copyright Clearance Center. The Preparation of Organotin Alkoxides, Use of tin derivatives as catalysts for transforming carbamates, carbamate compositions comprising said catalyst and method for transforming carbamates, Process for Production of Alkyltin Alkoxides, Process for production of dialkyltin dialkoxides, Method of preparing monomeric organotin dialkoxides, Method of preparing organo-substituted stannane derivatives, Process for preparing organotin alkoxides and phenoxides, Reaction products of dialkyl tin oxide and polyhydric phenols, Process for the preparation of dialkyltin dialkoxide, Process for production of alkyltin alkoxides, Multi-step method for the continuous preparation of organic polyisocyanates, Process for producing carboxylic acid esters from carboxylic acid halides and alcohols, Process for the preparation of n,o-disubstituted urethanes suitable as a starting material for the preparation of isocyanates, Process for cosynthesis of ethylene glycol and dimethyl carbonate, Process for the preparation of dialkyl carbonates, Process for preparation of bis- and tris(silylorgano)amines, Process for converting urethanes to isocyanates, Process for the preparation of diarylcarbonates, Method of obtaining alkoxides of alkyl tin, Process for the preparation of dialkylcarbonates, Process for the continuous thermal decomposition of esters of carbamic acids and use of mixtures of esters of carbamic acids and isocyanates obtained by this process for the preparation of isocyanates, Hydroxy carbamates and process of producing same, Depolymerization of poly (bisphenol A carbonate) under mild conditions by solvent-free alcoholysis catalyzed by 1, 8-diazabicyclo [5.4. 3972-6.
contained in this article in third party publications As such, temperature is a critical variable, while pressure is only helpful in reaching the desired temperatures and satisfactory rates of conversion. 17. keywords = "Alcohols, Alkylations, Carbamates, Carbonyldiimidazole (CDI), N-alkylimidazoles". The reactivation or regeneration of spent tin catalyst by treatment thereof with water, follow ed by alcohol and alkyl carbamate is also suitable for various other applications such as transesterification, esterification, ester interchange and transamination.
With one exception, reactions of six N,N-disubstituted β-aminoalcohols with CDI to form N-alkylimidazoles proceed under relatively mild conditions and may occur by way of an aziridinium intermediate.". Treatment of dibutyltin oxide with methanol and toluene at temperatures ranging from 115°-180° C. and pressures varying from ambient to 2.756 Mpa (400 psi) results in the formation of 1,3 bis(methoxy)tetrabutyl distannoxane, but does not produce the desired dibutyltin dimethoxide in any significant yield. However, under these rather forcing conditions, or even at lower reaction temperatures, elimination is a significant side reaction for benzylic secondary alcohols with β-hydrogen atoms. PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362.
Corresponding authors, a For benzylic primary alcohols, formation of N-alkylimidazoles proceeds reasonably at 170 °C in several different solvents and occurs by way of the initially formed carbamate. However, under these rather forcing conditions, or even at lower reaction temperatures, elimination is a significant side reaction for benzylic secondary alcohols with β-hydrogen atoms. If you are the author of this article you do not need to formally request permission
The process according to claim 17 wherein said catalyst product comprises dialkyltin dialkoxide in the range between about 90 to 98 mole % based on the tin species of said catalyst product. 11.
Optionally, the process according to the present invention can provide for the in-situ formation of alkyl carbamate from urea or the like and in the presence of excess alcohol at a temperature in the range between about 155° C. to 190° C., more preferably between about 155° C. to 170° C., and at an autogenous pressure. For example, a dialkyl carbonate reaction product synthesized from organic carbamates typically comprises alkyl carbamate, alkylated by-products, dialkyl carbonates, dialkyltin dialkoxide catalyst and carbonate-forming alcohol. For reproduction of material from all other RSC journals and books: For reproduction of material from all other RSC journals. the whole article in a third party publication with the exception of reproduction
to access the full features of the site or access our, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA, Instructions for using Copyright Clearance Center page. and is shown below in Equation 2: ##STR2##. There is an increasing use of carbamates in medicinal chemistry and many derivatives are specifically designed to make drug–target interactions through their carbamate moiety. This process is described in U.S. Pat. The present invention can also be used as a means of recycling and reactivating partially spent tin catalysts from the aforementioned applications by reconverting the inactive tin compounds to the dialkyltin dialkoxide by treatment with water followed by treatment with alcohol and alkyl carbamate as described herein. Alcohols which are most suited for use in converting dialkyltin oxide to dialkyltin dialkoxide in the presence of alkyl carbamate are methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, n-pentanol, 2-pentanol, 3-pentanol, isopentanol, n-octanol, cyclohexanol, n-dodecanol, isododecanol, etc. An alternative route involving the reaction of dibutyltin oxide with dimethyl carbonate (in the presence of traces of methanol) to produce 1,3bis(methoxy)tetrabutyl distannoxane exclusively is described in an article by Davies et al., entitled "Organic Chemistry, Part XI--The Preparation of Organotin Alkoxides", Journal of Chemical Society, (C) (1971), pp. The reaction of carbonyldiimidazole with alcohols to form carbamates and N-alkylimidazoles. Our approach to α-alkoxy carbamate synthesis employed a sequence of nitrile hydrozirconation, acylation, and alcohol addition. EXXON CHEMICAL PATENTS INC, DELAWARE, Free format text:
If you are the author of this article you still need to obtain permission to reproduce In this case alkyl carbamate and alcohol/NH3 are continuously distilled from the reactor and replaced with urea and fresh or recycled alcohol. Operating with sufficient pressure is important so far as it enables one to attain high enough temperatures for the reaction to proceed.
Voronkov and Yu P. Romadan, New Method for the Synthesis of Dialkyoxydialkyltins, Zhurnal Obshchei Khimii, vol. Tel: +1 412-624-8727. In all cases the Ref. R 2 NC(O)Cl + R'OH → R 2 NCO 2 R' + HCl. 2785-2786, Dec. 1969.
8 Conducting the multicomponent reaction at a late stage in the synthetic sequence provides abundant …
Urea can also be added to the reactor for a continuous operation. Go to our 19. Carbamates also arise via alcoholysis of chloroformamides: . The dibutyltin oxide is present in an amount of about 1 to 25 mole %, based on the total reaction mixture. formally request permission using Copyright Clearance Center. The Preparation of Organotin Alkoxides, Use of tin derivatives as catalysts for transforming carbamates, carbamate compositions comprising said catalyst and method for transforming carbamates, Process for Production of Alkyltin Alkoxides, Process for production of dialkyltin dialkoxides, Method of preparing monomeric organotin dialkoxides, Method of preparing organo-substituted stannane derivatives, Process for preparing organotin alkoxides and phenoxides, Reaction products of dialkyl tin oxide and polyhydric phenols, Process for the preparation of dialkyltin dialkoxide, Process for production of alkyltin alkoxides, Multi-step method for the continuous preparation of organic polyisocyanates, Process for producing carboxylic acid esters from carboxylic acid halides and alcohols, Process for the preparation of n,o-disubstituted urethanes suitable as a starting material for the preparation of isocyanates, Process for cosynthesis of ethylene glycol and dimethyl carbonate, Process for the preparation of dialkyl carbonates, Process for preparation of bis- and tris(silylorgano)amines, Process for converting urethanes to isocyanates, Process for the preparation of diarylcarbonates, Method of obtaining alkoxides of alkyl tin, Process for the preparation of dialkylcarbonates, Process for the continuous thermal decomposition of esters of carbamic acids and use of mixtures of esters of carbamic acids and isocyanates obtained by this process for the preparation of isocyanates, Hydroxy carbamates and process of producing same, Depolymerization of poly (bisphenol A carbonate) under mild conditions by solvent-free alcoholysis catalyzed by 1, 8-diazabicyclo [5.4. 3972-6.
contained in this article in third party publications As such, temperature is a critical variable, while pressure is only helpful in reaching the desired temperatures and satisfactory rates of conversion. 17. keywords = "Alcohols, Alkylations, Carbamates, Carbonyldiimidazole (CDI), N-alkylimidazoles". The reactivation or regeneration of spent tin catalyst by treatment thereof with water, follow ed by alcohol and alkyl carbamate is also suitable for various other applications such as transesterification, esterification, ester interchange and transamination.
With one exception, reactions of six N,N-disubstituted β-aminoalcohols with CDI to form N-alkylimidazoles proceed under relatively mild conditions and may occur by way of an aziridinium intermediate.". Treatment of dibutyltin oxide with methanol and toluene at temperatures ranging from 115°-180° C. and pressures varying from ambient to 2.756 Mpa (400 psi) results in the formation of 1,3 bis(methoxy)tetrabutyl distannoxane, but does not produce the desired dibutyltin dimethoxide in any significant yield. However, under these rather forcing conditions, or even at lower reaction temperatures, elimination is a significant side reaction for benzylic secondary alcohols with β-hydrogen atoms. PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362.
Corresponding authors, a For benzylic primary alcohols, formation of N-alkylimidazoles proceeds reasonably at 170 °C in several different solvents and occurs by way of the initially formed carbamate. However, under these rather forcing conditions, or even at lower reaction temperatures, elimination is a significant side reaction for benzylic secondary alcohols with β-hydrogen atoms. If you are the author of this article you do not need to formally request permission
The process according to claim 17 wherein said catalyst product comprises dialkyltin dialkoxide in the range between about 90 to 98 mole % based on the tin species of said catalyst product. 11.
Optionally, the process according to the present invention can provide for the in-situ formation of alkyl carbamate from urea or the like and in the presence of excess alcohol at a temperature in the range between about 155° C. to 190° C., more preferably between about 155° C. to 170° C., and at an autogenous pressure. For example, a dialkyl carbonate reaction product synthesized from organic carbamates typically comprises alkyl carbamate, alkylated by-products, dialkyl carbonates, dialkyltin dialkoxide catalyst and carbonate-forming alcohol. For reproduction of material from all other RSC journals and books: For reproduction of material from all other RSC journals. the whole article in a third party publication with the exception of reproduction
to access the full features of the site or access our, Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA, Instructions for using Copyright Clearance Center page. and is shown below in Equation 2: ##STR2##. There is an increasing use of carbamates in medicinal chemistry and many derivatives are specifically designed to make drug–target interactions through their carbamate moiety. This process is described in U.S. Pat. The present invention can also be used as a means of recycling and reactivating partially spent tin catalysts from the aforementioned applications by reconverting the inactive tin compounds to the dialkyltin dialkoxide by treatment with water followed by treatment with alcohol and alkyl carbamate as described herein. Alcohols which are most suited for use in converting dialkyltin oxide to dialkyltin dialkoxide in the presence of alkyl carbamate are methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, n-pentanol, 2-pentanol, 3-pentanol, isopentanol, n-octanol, cyclohexanol, n-dodecanol, isododecanol, etc. An alternative route involving the reaction of dibutyltin oxide with dimethyl carbonate (in the presence of traces of methanol) to produce 1,3bis(methoxy)tetrabutyl distannoxane exclusively is described in an article by Davies et al., entitled "Organic Chemistry, Part XI--The Preparation of Organotin Alkoxides", Journal of Chemical Society, (C) (1971), pp. The reaction of carbonyldiimidazole with alcohols to form carbamates and N-alkylimidazoles. Our approach to α-alkoxy carbamate synthesis employed a sequence of nitrile hydrozirconation, acylation, and alcohol addition. EXXON CHEMICAL PATENTS INC, DELAWARE, Free format text:
If you are the author of this article you still need to obtain permission to reproduce In this case alkyl carbamate and alcohol/NH3 are continuously distilled from the reactor and replaced with urea and fresh or recycled alcohol. Operating with sufficient pressure is important so far as it enables one to attain high enough temperatures for the reaction to proceed.