WO1993008150A1 - Esters d'hydrolyse utilisant des catalyseurs a base de 4-amino-pyridyle siloxane - Google Patents

Esters d'hydrolyse utilisant des catalyseurs a base de 4-amino-pyridyle siloxane Download PDF

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Publication number
WO1993008150A1
WO1993008150A1 PCT/US1991/007673 US9107673W WO9308150A1 WO 1993008150 A1 WO1993008150 A1 WO 1993008150A1 US 9107673 W US9107673 W US 9107673W WO 9308150 A1 WO9308150 A1 WO 9308150A1
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siloxane
methyl
silane
ester
polymer
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PCT/US1991/007673
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English (en)
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Martel Zeldin
Wilmer K. Fife
Slawomir Rubinsztajn
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Indiana University Foundation
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Priority to US08/211,761 priority Critical patent/US5442106A/en
Priority to PCT/US1991/007673 priority patent/WO1993008150A1/fr
Publication of WO1993008150A1 publication Critical patent/WO1993008150A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/09—Preparation of carboxylic acids or their salts, halides or anhydrides from carboxylic acid esters or lactones

Definitions

  • This invention resides generally in the fields of pyridine, silicon and catalyst chemistry. More particularly it relates to the use of a siloxane having 4-dialkylamino functions incorporated into its polymer backbone as a catalyst for the hydrolysis of esters.
  • This siloxane catalyst has shown remarkable selectivity and efficacy for the catalysis of esters, in some cases demonstrating enzyme-like substrate selectivity and catalytic efficacy.
  • 4-dialkylaminopyridines (“DAAP's”) are highly nucleophilic and exhibit catalytic activity toward a variety of reactions including acylations of derivatives of carbon, phosphorous and sulfur acids, and by silylations, ester rearrangements, polymerizations, redox and other reactions.
  • DMAP 4-dimethylaminopyridine
  • DMAP itself exhibits remarkable catalytic activity and has become a standard by which the activity of other DAAP compounds is often measured.
  • the efficacy of a subject DAAP compound in catalyzing a transacylation reaction of a sterically hindered alcohol suc as 1-methylcyclohexanol with an anhydride such as acetic anhydride is commonly compared to that of DMAP.
  • the rate of the transacylation catalyzed by DMA may be assigned a relative value of 1 (i.e., 100%), and the relative catalytic rate of the other DAAP compound is expressed as a fraction (i.e. percentage) thereof.
  • a relative value of 1 i.e., 100%
  • the relative catalytic rate of the other DAAP compound is expressed as a fraction (i.e. percentage) thereof.
  • vinyl-based polymeric catalysts with pendant DAAP groups have been prepared, including for instance: (1) poly[N-methyl-N-(4-vinylbenzyl)aminopyridine] , Menger, F.M. , McCann, D.J., J. Org. Chem. 1985, 50, 3928;
  • polymeric DAAP materials have been reported to exhibit high nucleophilicity in aqueous solution, although reports to this point have been quite limited. For example, only two such reports are presently known to applicant, those involving derivatives of polyethylene imine, Delaney, E.J., Wood, L.E., Klotz, I.M., J. Am. Chem. Soc. 1982 , 104, 799, and poly[4-(pyrrolidino)pyridines] , Vaidya, R.A. , Mathias, L.J., J. Am. Chem. Soc. 1986, 108, 5514.
  • one preferred embodiment of this invention relates to a process for hydrolyzing an activated ester.
  • This process comprises the step of hydrolyzing the ester in an aqueous medium in the presence of a catalytic amount of a siloxane having
  • the effective siloxane catalysts can be linear or cross-linked and homo- or copolymers, and are formed as fluids, gums, gels, elastomers or resinous materials, depending upon various factors including their degree of cross-linking, if any.
  • one preferred embodiment of the invention relates to a process for hydrolyzing an activated ester, which process comprises the step of hydrolyzing the ester in the presence of a catalytic amount of a siloxane having 4-dialkylaminopyridine groups incorporated into its polymer backbone.
  • activated ester means an ester which is susceptible to hydrolysis because of some structural feature of either its alcohol or acid portion.
  • activated esters include those which have alcohol portions which form weak bases. Representative activated esters thus include esters of para-nitrophenol, vinyl alcohol, enolpyruvate, etc.
  • activated esters also include esters which have carboxylic acid portions having electronegative groups attached, particularly at the alpha-carbon position. Representative activated esters thus also include esters of alpha-halogenated, alpha-hydroxylated, and alpha-aminated aliphatic carboxylic acids, to mention a few.
  • n an integer, typically about 3 to 30
  • the test results are then taken as a measure of the catalyst's esterase efficacy on activated esters generally. See, e.g. F.M. Congressr and C.E. Portnoy, J__. Am. Chem. Soc, 1967, ⁇ 9_, 4698; F.M. Congressr and M. Laidka, J. Am. Chem. Soc, 1987, 109, 3145; and G.E. Clement and M.L. Bender, Biochemistry, 1963, 2, 836.
  • the alcohol portion of activated esters is commonly occupied by other organic groups such as those specifically mentioned above, and, generally, can include groups such as alkyl, alkenyl (e.g.
  • ком ⁇ онент occupying the alcohol portion is not critical, so long as the ester as a whole is an activated ester as specified above and is soluble in the aqueous medium in which the hydrolysis is conducted.
  • alkanoate esters a C_ to C_ 0 alkanoate ester (i.e. in the carboxylic acid portion of the ester, C ⁇ H ⁇ COO-, n
  • the process of the present invention is conducted in an aqueous medium, preferably a buffered aqueous medium exhibiting a pH of about 8 to 9.
  • aqueous medium preferably a buffered aqueous medium exhibiting a pH of about 8 to 9.
  • suitable co-solvents will also be present to help solubilize the ester.
  • any co-solvent which is compatible with water and which provides a medium which solubilizes the ester will be suitable.
  • co-solvents thus include alcohols including lower alkyl alcohols such as methanol, ethanol, propanol, etc., as well as other water-compatible solvents such as acetonitrile, DMSO, THF, etc.
  • suitable co-solvent, and the relative amount of co-solvent to water will be within the ability of those ordinarily skilled in the relevant art.
  • siloxane polymers prepared by applicants have demonstrated remarkable thermal stability up to 375°C and above while preserving desirable catalytic and dynamic-mechanical properties over a wide temperature range from about -100°C to 375°C and above.
  • the siloxanes are thus good materials for general DAAP-type catalytic applications, far superior to their vinyl-based counterparts to date which suffer in many respects as noted above.
  • the catalytic siloxane polymer of the invention has 4-dialkylaminopyridine functions in its backbone.
  • siloxane is known in the art and used herein to mean a polymer containing -Si-O- units in its backbone.
  • Such -Si-O- units have occurred with or without other intermittent backbone structures.
  • the preferred siloxanes used in the present invention exemplify the former type of backbone structure, and accordingly have he. backbones with repeating units of -Si-R-Si-O- wherein R is a nitrogenous organic component (e.g. siloxane species 5a, 5b, 6a and 6b identified below) which includes the DAAP function.
  • R is a nitrogenous organic component
  • Other siloxanes which the applicants have prepared have exemplified the latter type (e.g. species 3a, 3b, 4a and 4b below). In the applicants* work thus far, these latter siloxanes have not proven to have the highly advantageous catalytic behavior towards the hydrolysis of esters as do the former siloxanes mentioned above.
  • the preferred siloxanes for use in the present invention can be prepared as homo- or copolymers, linear or cross-linked, and in some instances have been end-blocked as further discussed below.
  • These siloxanes are formed as fluids, gums, swellable gels, elastomers or resinous materials, largely depending upon the degree of their cross-linking, if any, as well their molecular weight (degree of polymerization) and other factors well known to those experienced in this area.
  • preferred linear siloxane homo- and copolymers prepared according to the invention have been soluble in organic solvents, and have exhibited variation in molecular weights
  • siloxanes studied by applicants have each been prepared from a silane comprising a (i.e. at least one) 4-dialkylaminopyridine function having at least one silyl component attached to its 4-dialkylamino moiety.
  • This silyl component is in turn functionalized with one, two or three radicals which facilitate the polymerization and/or substrate-binding process. To date, the applicants have worked with alkoxy groups in this position.
  • alkoxy or other radicals are functionalize the silyl component by providing a silicon bond which is labile in aqueous or other protic solvents.
  • groups which possess this same functionalizing property and are effective substitutes for the alkoxy groups in the applicants' experiments so far.
  • these include cycloalkoxy (e.g., -O-cylcohexyl) , aralkoxy and acyloxy groups, amino groups, halo groups (preferably chloro), and many others.
  • the siloxane containing in-chain 4-dialkylamino pyridine groups which is used in the present invention has been prepared from a silane having two such silyl components connected to the DAAP function, and wherein each silyl component is at least mono-functional.
  • silanes used by applicants thus far in the following formulas, in which silanes of the formula (2) lead to siloxane polymers usable in the present invention:
  • R to date comprises lower alkyls with methyl, ethyl, propyl and iso-propyl being preferred thus far.
  • silanes which lead to siloxanes usable within the spirit and scope of the present invention can be readily prepared with similar effective properties and being at least functional equivalents to those defined above.
  • the spacer group separating the aminopyridyl moiety from the silicon i.e.
  • trimethylene [(CH )_] in the formulas above can be another organic group, including for instance a shorter or longer, branched or unbranched radical that may be an alkyl, aryl or aralkyl (i.e. benzyl) group. Such replacements are well within the knowledge and skill of those experienced in this field in view of a specific circumstance or compound under consideration.
  • methyl groups defined above can likewise be replaced with other organic groups.
  • These include longer, branched or unbranched alkyl groups such as ethyl, propyl, iso-propyl, butyl, iso-butyl, etc., as well as aryl or aralkyl and other groups, all of which have effective properties to function within the invention as defined and claimed herein.
  • silanes used in the applicants' studies to date according to the above formulas are as follows, with silanes 2a, 2b and 2c leading to siloxanes usable in the present invention: No. Name la. N-(3-(Diethoxy(methyl)silyl)propyl)-N-methyl-4-aminopyrid lb. N-(3-(Triethoxysilyl)propyl)-N-methyl-4-aminopyridine 2a. N,N[Bis(3-(dimethyl(ethoxy)silyl)propyl)]-4-amino ⁇ yridine 2b.
  • silanes have been prepared by hydrosilation of 4-(N-methylallylamino)pyridine or 4-(N-diallylamino)pyridine with triethoxysilane [(EtO SiH], diethoxy(methyl)silane [(EtO) 2 MeSiH] or dimethyl(ethoxy)silane [(EtO)Me SiH] .
  • a suitable catalyst such as chloroplatinic acid or a coordination complex such as PdCl-, RhCl(PPh 3 ) 3 or Co(CO) g .
  • DAAP functionality in the prepared polymers has been pendant from or incorporated into the siloxane polymer backbones, with the latter being used in the processes of the present invention.
  • linear (i.e., 3a and 3b) and crosslinked (i.e., 4a and 4b) polymers having pendant DAAP groups have been prepared having repeating units consistent with the following formulas:
  • these siloxane materials have bee prepared to date by hydrolysis polymerization of a suitable silane monomer as described in detail above which includes a 4-dialkylaminopyridine function having an alkoxysilyl group attached to its 4-dialkylamino moiety.
  • a suitable base catalyst therefor as those practiced in this field will recognize.
  • suitable catalysts for this operation generally include, but are not limited to, negatively-charged oxygen species such as hydroxide ion, which can be provided by suitable salts such as Me.NOH, KOH and many others also known in the art.
  • linear siloxane homopolymers such a those of 3a and 5a above have been prepared by base-catalyzed hydrolytic polycondensations of difunctional silane monomers such as la and 2a above in THF/H-0 mixtures.
  • Resulting hydroxyl-terminated siloxanes may be end-blocked with a suitable end-blocking agent such as (Me 3 Si) 0, (Me_Si) confrontNH, Me_SiX (where X is a halogen such as Cl, or alkoxy such as methoxy, ethoxy, or propoxy) , or bis(trimethylsilyl)acetamide.
  • the molecular weight (M ) of the polymer obtained has depended upon factors such as the monomer:catalyst ratio used, and has been determined in the Examples below using exclusion chromatography and viscosity measurements.
  • the preferred fluid polymers of the invention are soluble in chlorinated hydrocarbons, THF and alcohols.
  • Copolymers such as 3b and 5b above incorporating -Me-SiO- units into their polymer backbones have also been prepared by reaction of difunctional silane monomers such as la and 2a above either with Me 2 Si(OEt) 2 by hydrolytic polycondensation or with linear or cyclic siloxane oligomers (e.g. HO(SiMe 2 0) ⁇ H, (Me 2 SiO) 3 or (Me 2 SiO) 4 ) by ring opening redistribution polymerization.
  • difunctional silane monomers such as la and 2a above either with Me 2 Si(OEt) 2 by hydrolytic polycondensation or with linear or cyclic siloxane oligomers (e.g. HO(SiMe 2 0) ⁇ H, (Me 2 SiO) 3 or (Me 2 SiO) 4 ) by ring opening redistribution polymerization.
  • crosslinked materials as represented by 4a, 4b, 6a and 6b above have also been prepared.
  • Some of these crosslinked siloxanes have been obtained by polymerization of difunctionalized DAAP-containing silanes such as those of la and 2a above in the presence of tri- or tetrafunctional silane such as Me Si(OEt) 4 _ where n is 0 or 1, respectively.
  • Others have been prepared by polymerization of at least trifunctional DAAP-containing silanes, for example those of 2b and 2c above, with possible inclusion of cyclic or linear dimethylsiloxyl oligomers and in the presence of these same tri- or tetrafunctional silanes.
  • These crosslinked polymers and co-polymers have to date formed swellable gels, elastomers or insoluble resins depending upon their degrees of crosslinking and other factors. Further details as to the prepared siloxanes can be found in Examples 6-12 below.
  • one accepted standard way to test the ability of a catalyst to effect a reaction such as a transacylation is to evaluate its efficacy in catalyzing the reaction of a sterically-hindered alcohol such as 1-methylcyclohexanol with an anhydride such as acetic anhydride.
  • a sterically-hindered alcohol such as 1-methylcyclohexanol
  • an anhydride such as acetic anhydride.
  • Silane la was prepared by first preparing and then hydrosilating 4-(N-methylallylamino)pyridine with diethoxy(methyl)silane, (EtO) 2 MeSiH.
  • 4-(N-methylallylamino)pyridine was first obtained by reaction of 4-chloropyridine and N-methylallylamine.
  • 4-chloropyridine (11.4 g; 0.1 mol) and N-methylallylamine (7.1 g; 0.1 mol) were combined in a glass ampoule or steel container, after which the mixture was degassed under vacuum and the vessel was sealed.
  • the vessel was heated for three days at 130°C.
  • the vessel was thereafter opened and the contents were dissolved in water and then neutralized with 10% aqueous NaOH.
  • the aqueous solution was extracted with several portions of diethyl ether.
  • the ether extract was filtered and evaporated.
  • silane lb To prepare silane lb, the procedure of Example 1 was repeated except triethoxysilane _(EtO)_SiH] was used instead of the dietho y(methyl)silane.
  • the title compound was prepared by a the procedure of Example 3 except diethoxy(methyl)silane [(EtO)-MeSiH] was used in the place of the dimethyl(ethoxy)silane.
  • Silane 2c was prepared by the procedure of Example 3 except triethoxysilane [(EtO)-SiH] was used instead of the dimethyl(ethoxy)silane.
  • the mixture was stirred at room temperature for 12 hours. Volatile materials were removed under vacuum and the polymeric product was heated under vacuum at 80°C for 12 hours. The temperature was then raised to 140°C for 20 minutes.
  • the Siloxane 3a product is a pale-yellow, viscous fluid, with molecular weight dependent on the ratio of monomer-to-catalyst and conditions of reaction.
  • Polymer 3a is soluble in CH 2 C1 2 , THF, and methanol, was characterized by elemental analysis, spectroscopic methods and thermal analysis (DSC and TGA) , and exhibited a T, of
  • Siloxane 5a is soluble in CHforceC1 assigned to the following properties: Siloxane 5a is soluble in CHforceC1 assigned to the following properties: Siloxane 5a is soluble in CHforceC1 assigned to the following properties: Siloxane 5a is soluble in CHforceC1 assigned to the following properties: Siloxane 5a is soluble in CHforceC1 assigned to the following properties: Siloxane 5a is soluble in CHforceC1 radical, ether, toluene and methanol, was characterized by elemental analysis, spectroscopic methods and thermal analysis (DSC and TGA) , and demonstrated a T, of 427°C.
  • the resulting co-polymer 4b is a pale yellow viscous fluid which is soluble in organic solvents such as halogenated and aromatic hydrocarbons, and THF, and has a T fl from 370°C to 445°C depending upon the relative quantities of the reactants and molecular weight, and to some extent of course upon the purity of the sample tested.
  • the molecular weight of the co-polymer obtained depended on the ratio of reaction monomer and co-oligomer, and the relative quantities of (Me 3 Si) 2 0 and catalyst.
  • the resulting co-polymer 5b is a pale yellow viscous fluid which is soluble in halogenated and aromatic hydrocarbons, and THF, and has a T, of 425°C to 455°C depending upon the relative quantities of reactants used in preparation and molecular weight, and of course to some extent upon purity.
  • the molecular weight of the co-polymer obtained depended on the relative quantities of reactants used and the relative quantities of (Me 3 Si) 2 0 and catalyst.
  • N-(3-(diethoxy(methyl)silyl)propyl)-N-methyl-4-aminopyridine or N,N[bis(3-(dimethyl(ethoxy)silyl)propyl)-4-aminopyridine (Silane la or 2a) was dissolved in a mixture of THF and i-PrOH (1:1 v/v).
  • Crosslinking agent [methyltriethoxysilane (0.50 equiv.)], NH 3 (aq) (3 equiv., 6N) , and Me.NOH were added to the solution and the mixture was stirred for 12 hours at 60°C. Volatile materials were removed by heating the mixture at 80°C for 12 hours under vacuum.
  • the temperature of the residue was raised to 140°C for 6 hours.
  • the resulting polymer products (4a and 6a, respectively) are rubbery materials which swell in CH 2 C1 2 or THF, and have respective d 's of 460°C and 375°C.
  • Table 1 summarizes these two experiments and similar experiments using varying crosslinking agent and co-monomer combinations (numbers in parentheses represent equivalents used) .
  • Example 10 A procedure analogous to that of Example 10 (except no crosslinking agent or co-reactant was added) was used to prepare a crosslinked homopolymer from silane 2b, N,N[bis(3-(diethoxy(methyl)silyl)propyl)]-4-aminopyridine.
  • the resulting siloxane polymer is a highly crosslinked resin exhibiting good DAAP catalytic properties as illustrated in Table 3 below.
  • Example 7 The polymer of Example 7 was evaluated as a catalyst for hydrolysis of organic esters of alkanoic acids. Studies of this type frequently use para-nitrophenyl alkanoates as a test substrate to measure the relative efficacy of the catalyst. Accordingly, kinetic measurements were carried out as follows. Reaction mixtures were prepared in a 1.00 cm quartz cuve . The cuvet was filled with 2.97 ml of a 1:1 mixture of methanol and aqueous buffer (0.05 M
  • H POVHPO " pH 8.0
  • a stock solution of catalyst in methanol (usually 5 ⁇ L) was added by microsyringe and the solution was equilibrated for 10 min. in the ther ostatted cell compartment (30° plus or minus 1°C) of a Hewlett-Packard Model 8450 spectrophotometer.
  • An appropriate aliquot (0.03 mL) of a stock solution of para-nitrophenyl alkanoate in dioxane was added by microsyringe.
  • the reaction mixture was quickly mixed by shaking, and the absorbance at 400 nm was recorded as a function of time.
  • the siloxane of Example 7 not only exhibits high levels of catalytic efficiency and conforms to the Michaelis-Menten model, but also demonstrates enzyme-like specificity for esters derived from carboxylic acids of moderate chain length (e.g. about C. 2 to C, ⁇ ), with C, 4 esters being the optimum substrate in the applicants' studies thus far.

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Abstract

Cette invention concerne des procédés préférés permettant d'effectuer l'hydrolyse d'esters activés en utilisant comme catalyseurs des siloxanes dans lesquels des groupes 4-dialkylaminopyridyle sont incorporés dans leurs squelettes polymères. Les matériaux préférés pour les catalyseurs au siloxane présentent une efficacité catalytique inattendue dans l'hydrolyse ainsi qu'une sélectivité du type enzyme pour les substrats d'esters.
PCT/US1991/007673 1991-10-15 1991-10-15 Esters d'hydrolyse utilisant des catalyseurs a base de 4-amino-pyridyle siloxane WO1993008150A1 (fr)

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US08/211,761 US5442106A (en) 1991-10-15 1991-10-15 Process for hydrolyzing esters using 4-aminopyridyl siloxane catalysts
PCT/US1991/007673 WO1993008150A1 (fr) 1991-10-15 1991-10-15 Esters d'hydrolyse utilisant des catalyseurs a base de 4-amino-pyridyle siloxane

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5502248A (en) * 1995-02-27 1996-03-26 Uop Process for concurrent hydrolysis of esters and separation of products using a simulated moving bed
WO1999006370A1 (fr) * 1997-08-01 1999-02-11 Reilly Industries, Inc. Catalyseurs pyridines 4-substitues supernucleophiles, et procedes utiles pour la preparation de ceux-ci
WO2010105942A1 (fr) * 2009-03-20 2010-09-23 Henkel Ag & Co. Kgaa Dérivés de 4-aminopyridine en tant que catalyseurs pour la dissociation d'esters organiques
CN108611083A (zh) * 2018-05-08 2018-10-02 中国石油集团川庆钻探工程有限公司长庆井下技术作业公司 一种清洁压裂液用生物酶破胶剂及其制备方法
KR102727040B1 (ko) 2019-09-24 2024-11-07 주식회사 엘지화학 변성 공액디엔계 중합체, 이의 제조방법 및 이를 포함하는 고무 조성물

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4942254A (en) * 1981-11-05 1990-07-17 Union Oil Company Of California Methods for acid catalyzed reactions

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4942254A (en) * 1981-11-05 1990-07-17 Union Oil Company Of California Methods for acid catalyzed reactions

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5502248A (en) * 1995-02-27 1996-03-26 Uop Process for concurrent hydrolysis of esters and separation of products using a simulated moving bed
WO1999006370A1 (fr) * 1997-08-01 1999-02-11 Reilly Industries, Inc. Catalyseurs pyridines 4-substitues supernucleophiles, et procedes utiles pour la preparation de ceux-ci
US6369230B1 (en) 1997-08-01 2002-04-09 Reilly Industries, Inc. Supernucleophilic 4-substituted-pyridine catalysts, and processes useful for preparing same
US6603010B2 (en) 1997-08-01 2003-08-05 Reilly Industries, Inc. Supernucleophilic 4-substituted-pyridine catalysts, and processes useful for preparing same
WO2010105942A1 (fr) * 2009-03-20 2010-09-23 Henkel Ag & Co. Kgaa Dérivés de 4-aminopyridine en tant que catalyseurs pour la dissociation d'esters organiques
CN108611083A (zh) * 2018-05-08 2018-10-02 中国石油集团川庆钻探工程有限公司长庆井下技术作业公司 一种清洁压裂液用生物酶破胶剂及其制备方法
CN108611083B (zh) * 2018-05-08 2020-11-13 中国石油天然气集团有限公司 一种清洁压裂液用生物酶破胶剂及其制备方法
KR102727040B1 (ko) 2019-09-24 2024-11-07 주식회사 엘지화학 변성 공액디엔계 중합체, 이의 제조방법 및 이를 포함하는 고무 조성물

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