US20100210788A1

US20100210788A1 - Electron deficient olefins

Info

Publication number: US20100210788A1
Application number: US12/766,457
Authority: US
Inventors: Ciaran B. McArdle; Ligang Zhao; Stefano Gherardi; Kevin Murnaghan
Original assignee: Henkel Loctite Ireland Ltd
Current assignee: Henkel IP and Holding GmbH
Priority date: 2007-10-24
Filing date: 2010-04-23
Publication date: 2010-08-19
Also published as: ES2634631T3; CN102083784A; EP2217559A2; EP2217559B1; JP5639892B2; US20150191424A1; US20160075641A1; JP2011500769A; CA2703603A1; US9481640B2; KR20100097116A; KR101571913B1; WO2009053484A2; WO2009053484A3

Abstract

This invention relates to novel electron deficient olefins, such as certain 2-cyanoacrylates and methylidene malonates, prepared using an imine or an iminium salt.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to novel electron deficient olefins, such as certain 2-cyanoacrylates or methylidene malonates, prepared using an imine or an iminium salt.
2. Brief Description of Related Technology
Cyanoacrylate adhesives are known for their fast adhesion and ability to bond a wide variety of substrates. They are marketed as “super glue” type adhesives. They are useful as an all-purpose adhesive since they are a single component adhesive, very economical as only a small amount will do, and generally do not require any equipment to effectuate curing.
Traditionally, cyanoacrylate monomers have been produced by way of a Knoevenagel condensation reaction between a formaldehyde precursor, such as paraformaldehyde, and an alkyl cyanoacetate with a basic catalyst. During the reaction, cyanoacrylate monomer forms and polymerises in situ to a prepolymer. The prepolymer is subsequently thermally cracked or depolymerised, yielding cyanoacrylate monomer. This approach has remained essentially the same over time, though various improvements and variants have been introduced. See e.g. U.S. Pat. Nos. 6,245,933, 5,624,699, 4,364,876, 2,721,858, 2,763,677 and 2,756,251.
In U.S. Pat. No. 3,142,698, the synthesis of difunctional cyanoacrylates using a Knoevenagel condensation reaction is described. However, the ability to thermally depolymerise the resulting, now crosslinked, prepolymer in a reliable and reproducible manner to produce pure difunctional monomers in high yields is questionable [see J. Buck, J. Polym. Sci., Polym. Chem. Ed., 16, 2475-2507 (1978), and U.S. Pat. Nos. 3,975,422, 3,903,055, 4,003,942, 4,012,402, and 4,013,703].
A variety of other processes for producing cyanoacrylate monomers are known, some of which are described below. For instance, U.S. Pat. No. 5,703,267 defines a process for producing a 2-cyanoacrylic acid which comprises subjecting a 2-cyanoacrylate and an organic acid to a transesterification reaction.
U.S. Pat. No. 5,455,369 defines an improvement in a process for preparing methyl cyanoacrylate, in which methyl cyanoacetate is reacted with formaldehyde to form a polymer that is then depolymerized to the monomeric product, and in which the purity of yield is 96% or better. The improvement of the '369 patent is reported to be conducting the process in a poly(ethylene glycol)diacetate, dipropionate, or dibutyrate, having a number average molecular weight of 200-400, as the solvent.
U.S. Pat. No. 6,096,848 defines a process for the production of a biscyanoacrylate, which comprises the steps of esterifying a 2-cyanoacrylic acid or transesterifying an alkyl ester thereof to obtain a reaction mixture; and fractionally crystallizing the reaction mixture to obtain the biscyanoacrylate.
U.S. Pat. No. 4,587,059 defines a process for the preparation of monomeric 2-cyanoacrylates comprising the steps of (a) reacting (i) a 2,4-dicyanoglutarate with (ii) formaldehyde, cyclic or linear polymers of formaldehyde, or a mixture thereof, in the presence of between about 0.5 and about 5 mols of water per mol of 2,4-dicyanoglutarate, at an acid pH of about 3 to slightly less than 7, and at a temperature of about 70 to about 140, to form an oligomeric intermediate product, and (b) removing water that is present from step (a) and thermolyzing the oligomeric intermediate product for a period of time sufficient to effect its conversion to monomeric 2-cyanoacrylates.
Commercial production of cyanoacrylate monomers ordinarily relies on the depolymerisation of a prepolymer formed under Knoevenagel condensation reaction conditions, as noted above. Still today the Knoevenagel condensation reaction is believed to remain the most efficient and prevalent commercial method for producing high yields of monofunctional cyanoacrylates. Nevertheless, it would be desirable to not have to resort to thermally induced depolymerisation of a prepolymer produced by the Knoevenagel condensation reaction. This prospect may also enable facile access to highly useful difunctional monomers, such as so-called biscyanaocrylates or hybrid materials of cyanoacrylate and other polymerisable or reactive functionality.
For instance, cyanoacrylate esters bearing moisture, base, acid, thermally sensitive or otherwise reactive moieties, may not be conveniently produced and isolated under Knoevenagel reaction conditions.
While methods describing the preparation of cyanoacrylates with reactive functionality in the ester side chain (such as biscyanoacrylates) are known (see e.g. Buck and U.S. Pat. Nos. 3,975,422, 3,903,055, 4,003,942, 4,012,402, and 4,013,703), the cyanoacrylates with reactive functionality in the ester side chain are prepared in a multi-step process involving protective group strategies and functional group transformations to arrive at adducts which must subsequently be deprotected to yield cyanoacrylates with additional functionality. The same approach has been described to arrive at a cyanoacrylate-capped polyisobutylene by Kennedy et al., J. Macromol Sci. Chem., A28, 209 (1991).
A transesterification approach to achieve cyanoacrylates with reactive functions in the ester side chain has also been described in U.S. Pat. No. 6,096,848, in which cyanoacrylate esters, previously made by Knoevenagel reaction, are hydrolysed in strong acid conditions in the presence of a difunctional alcohol to yield biscyanoacrylates. The method described in the '848 patent requires long reaction times, copious volumes of solvent and solvent switching methods to isolate the bifunctional cyanoacrylates free from acid stablisers in modest to low yields [see also Khrustalev et al., Russian Chem. Bull., 45, 9, 2172 (1996)].
An alternative approach to the preparation of cyanoacrylates with reactive functions in the ester side chain uses cyanoacrylic acid or its acid chloride (cyanoacryloyl chloride). See e.g. International Patent Publication Nos. WO 94/15590A1, WO 94/115907A1, and WO 95/32183A1, and U.S. Pat. No. 5,703,267.
The use of cyanoacrylic acid and cyanoacryloyl chloride to arrive at cyanoacrylates has also been described in Y. Gololobov and I. Chernoglazova, Russian Chem. Bull., 42, 5, 961 (1993) and Y. Gololobov and M. Galkina, Russian Chem. Bull., 44, 4, 760 (1995). These methods require flash vacuum pyrolysis techniques conducted in quartz tubes at high temeperatures (approximately 600° C.) and exposure of highly reactive, polymerisable intermediate materials to chemical reactions with highly acidic and moisture sensitive reagents.
With regard to the preparation of other types of electron deficient olefins with reactive functionality, U.S. Pat. No. 5,142,098 describes a copper catalysed reaction of malonates and formaldehyde to form methylidenemalonate monomers that are trapped in situ by a “diene” anthracene in a Diels-Alder reaction. The '098 patent describes a diester adduct of anthracene, that is a precursor for a methylidenemalonate monomer with one ethyl ester and one glycidyl ester. The '098 patent indicates that reaction—a retro Diels-Alder thermolysis step—was not successful for the preparation of the particular methylidene malonate bearing the glycidyl functionality in the ester side chain. The retro Diels-Alder reaction has been reported as useful in the syntheses of other methylidene malonates (see e.g. J-L. De Keyser et al., J. Org. Chem., 53, 4859 (1988)).
Accordingly, it will be appreciated that the preparation of electron deficient olefins, such as 2-cyanoacrylates or methylidene malonates, with a reactive functional group in the ester, or even with large or bulky groups in the ester side chain, is not a trivial matter.
As a result and because of the limitations of the hitherto known various processes for cyanoacrylate synthesis and the sensitivity of the novel electron deficient olefins, such novel electron deficient olefins have not been described to date. Until now.

SUMMARY OF THE INVENTION

Unlike the state of the technology, the present invention provides novel electron deficient olefins, such as 2-cyanoacrylates or methylidene malonates, with a reactive functional group in the ester side chain, prepared using an imine or an iminium salt.
The novel compounds are electron deficient olefins within structure I:
where X is (a) an electron withdrawing group, or
(b) Y;

Y is

- where D is selected from H, alkyl or aryl, Z is either
  - (i)

- where Q is
  - a. an electron withdrawing group (such as CN, CO₂R, CO₂H, COCl, COR, COPO(OR)₂, COPOR₂, SO₂R, SO₃R or NO₂) or
  - b. a first reactive functionality, or
- (ii) a second reactive functionality, g is 1-10; and

n is 0 or 1.
Desirably, g is 1. However, if g>1, D is should be H.
More specifically, the inventive compounds are embraced by structure II
where X is an electron withdrawing group or E, E is as shown,
is a reactive functionality, D is selected from H, alkyl or aryl, n is 0 or 1, and A, B, 1, 2, 3, 4, 5, and 6 are each references to bond designations.
In an alternative aspect the inventive compounds are embraced by structure III
where X is an electron withdrawing group or F, D is selected from H, alkyl or aryl, Z is a reactive functionality, n is 0 or 1 and g is 1. The reactive functionality of Z in structure III may be selected from epoxides, episulfides, oxetanes, thioxetanes, dioxolanes, dioxanes, isocyanates, maleimides, oxazolines, succinimides, 2-cyanoacrylates, methyiidene malonates, acrylonitrile, (meth)acrylates, carboxylic acids and derivatives thereof, cyanoacetates, methylene malonates, hydroxyls, silanes, siloxanes, titanates, or zirconates.
The present invention also provides compositions of the compounds of structures I, together with a stabilizer package comprising at least one of a free radical stabilizer and an anionic stabilizer; and optionally, one or more additives selected from cure accelerators, thickeners, thixotropes, tougheners, thermal resistance-conferring agents, or plasticizers.
The present invention further provides compositions of the compounds of structures I, II or III, together with a cyanoacrylate or a methylidene malonate. Or the present invention further provides compositions of certain of the compounds of structures I, II or III, together with a coreactant, such as one selected from epoxides, episulfides, oxetanes, thioxetanes, dioxolanes, dioxanes, isocyanates, maleimides, oxazolines, (meth)acrylates, cyanoacrylates, methylidene malonates or vinyl ethers.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts a synthetic scheme by which iminium salts may be prepared.

FIG. 2 depicts a synthetic scheme by which a precursor to an inventive electron deficient olefin may be prepared.

FIG. 3 depicts a synthetic scheme by which the precursor to an inventive electron deficient olefin (from FIG. 2) is used with the iminium salt (from FIG. 1) to form the inventive electron deficient olefin.

DETAILED DESCRIPTION OF THE INVENTION

As noted above, the present invention provides electron deficient olefins within structure I:
where X is (a) an electron withdrawing group, or (b) Y;
Y is
where D is selected from H, alkyl or aryl, Z is either

- (i)

where Q is

- a. an electron withdrawing group (such as CN, CO₂R, CO₂H, COCl, COR, COPO(OR)₂, COPOR₂, SO₂R, SO₃R or NO₂) or
- b. a first reactive functionality, or
- (ii) a second reactive functionality, g is 1-10; and

n is 0 or 1.
Desirably, g is 1. However, if g>1, D is should be H.
More specifically, the inventive compounds are embraced by structure II
where X is an electron withdrawing group (such as CN, CO₂R, CO₂H, COCl, COR, COPO(OR)₂, COPOR₂, SO₂R, SO₃R or NO₂, where R is C_1-4) or E, E is as shown,
is a reactive functionality, D is selected from H, alkyl or aryl, n is 0 or 1, and A, B, 1, 2, 3, 4, 5, and 6 are each references to bond designations. Q may be an amide or thioamide embraced by
C(T)NUV,
where T is O or S and U or V are each independently selected from H or R, where R is C_1-4. In addition, in structure II, the vinyl group labeled ‘6’ is disposed 6 bond lengths distance from the vinyl group labeled ‘1’, ignoring side branches and where Q is not H.
In an alternative aspect the inventive compounds are embraced by structure III
where X is an electron withdrawing group (such as CN, CO₂R, CO₂H, COCl, COR, COPO(OR)₂, COPOR₂, SO₂R, SO₃R or NO₂, where R is C_1-4) or F, D is selected from H, alkyl or aryl, Z is a reactive functionality, n is 0 or 1 and g is 1. The reactive functionality of Z in structure III may be selected from epoxides, episulfides, oxetanes, thioxetanes, dioxolanes, dioxanes, isocyanates, maleimides, oxazolines, succinimides, 2-cyanoacrylates, methylidene malonates, acrylonitrile, (meth)acrylates, carboxylic acids and derivatives thereof, cyanoacetates, methylene malonates, hydroxyls, silanes, siloxanes, titanates, or zirconates.
Representative examples of novel electron deficient olefins within the scope of the invention include
To prepare such compounds in accordance with the present invention, one may use imines embraced by structure VI or iminium salts embraced by structure VII.
The imine embraced within structure VI is as follows:
where K is

where in this connection R₁-R₂are each independently selected from hydrogen, alkenyl, or alkynyl; and A-B are each independently selected from linear, branched, or cyclic alkyl or alkenyl which may be interrupted with heteroatoms or substituted by functional groups, or A and B taken together form a cyclic or polycyclic alkyl or alkenyl structure, which may be interrupted with heteroatoms or substituted by functional groups;
E is selected from a linear, branched or cyclic hydrocarbon with or without one or more nitrogen-containing substituents thereon, a heterocyclic, an aromatic or an organosiloxane group or part thereof or linkage; and
R₃in this connection is selected from a hydrocarbon, a heterocyclic, an aromatic or an organosiloxane group or linkage;
w is 1-100; y is 1-100 and z is 0-100.
When more than one of K, E or R₃are present, each instance thereof is defined independently from the other instance(s).

The imine more specifically is embraced within structure VIA as follows:
where in this connection R₁-R₂, A-B, E, R₃, w, y and z are as defined above.
The iminium salt embraced within structure VII is as follows:
where K is

where in this connection R₁-R₂are each independently selected from hydrogen, alkenyl, or alkynyl; and A-B are each independently selected from linear, branched, or cyclic alkyl or alkenyl which may be interrupted with heteroatoms or substituted by functional groups, or A and B taken together form a cyclic or polycyclic alkyl or alkenyl structure, which may be interrupted with heteroatoms or substituted by functional groups;
E is selected from a linear, branched or cyclic hydrocarbon with or without one or more nitrogen-containing substituents thereon, a heterocyclic, an aromatic or an organosiloxane group or part thereof or linkage; and
R₃in this connection is selected from a hydrocarbon, a heterocyclic, an aromatic or an organosiloxane group or linkage;
w is 1-100; y is 1-100 and z is 0-100; and
X is an anion.
When more than one of K, E or R₃are present, each instance thereof is defined independently from the other instance(s).

The iminium salt is embraced more specifically by structure VIIA as follows:
where in this connection R₁-R₂, A-B, E, R₃, w, y and z, and X are as defined above.
The imine in some cases may be an imine having an onium salt, such as an ammonium or amine salt functionality. In some cases the imines may be termed an “ionic liquid” (or “IL”) or a task specific ionic liquid (or, “TSIL”), as will be discussed in more detail below. Likewise, the iminium salts may be termed an “ionic liquid” (or “IL”) or a task specific ionic liquid (or, “TSIL”), as will be discussed in more detail below.
In such cases where the imine of structure VI or the iminium salt of structure VII is particularly stable at room temperature conditions when in the presence of the precursor to the electron deficient olefin, a modest amount of heat may be useful to allow the reaction to generate electron deficient olefins. Exposure to elevated temperature conditions is particularly desirable with iminium salts of structure VII.
Reference to the figures may be useful to appreciate further how electron deficient olefins of the present invention are prepared, which is described in more detail below and in the Examples section that follows thereafter.
Thus, as an initial reactant, is an aldehyde compound having the structure R₃R₄C═O, where R₃is hydrogen and R₄is a hydrogen, vinyl or propargyl. The aldehyde compound may be an aldehyde itself or a source of an aldehyde, such as one that yields an aldehyde like formaldehyde under appropriate reaction conditions. The aldehyde compound in a desirable embodiment includes formaldehyde or a source thereof, such as paraformaldehyde (see FIG. 1), formalin, or 1,3,5-trioxane, or vinyl aldehydes, such as acrolein.
As a reactant with such an aldehyde is a primary amine. Primary amines attached to a carbon bearing no alpha protons are particularly desirable, such as t-alkyl primary amines. Rohm and Haas Co., Philadelphia, Pa. has sold commercially for a number of years a series of t-alkyl primary amines, which are designated as PRIMENE-brand amines.
For instance, t-alkyl primary amines available from Rohm and Haas include PRIMENE 81-R and PRIMENE JM-T. These PRIMENE-brand t-alkyl primary amines have highly branched alkyl chains (represented schematically by circle symbols in the Figures for simplicity) in which the amino nitrogen atom is attached directly to a tertiary carbon. These t-alkyl primary amines consist of mixtures of isomeric amines, with PRIMENE 81-R consisting of an isomeric mixture with C₁₂-C₁₄carbon branches and having an average molecular weight of 185 and PRIMENE JM-T consisting of an isomeric mixture with C₁₆-C₂₂carbon branches and having average molecular weight of 269.
PRIMENE MD, also known as menthanediamine (1,8-diamino-p-menthane) or (4-amino-α,α-4-trimethyl-cyclohexanemethanamine, CAS No. 80-52-4), is a primary alicyclic diamine, in which both amino groups are attached to tertiary carbon atoms. Like other alicyclic t-alkyl primary amines, menthanediamine is somewhat less reactive than similar straight chain diamines. Yet another PRIMENE, PRIMENE TOA has tertiary octyl chains and a molecular weight of 129. In the examples given below, PRIMENE 81-R MSA iminium salt, formed in reaction (2) of FIG. 1, is used.
The imines, whether or not bearing ammonium salt functionality or whether or not they are tethered to a support, are then reacted with compounds containing a methylene linkage having at least one, desirably two, electron withdrawing substituent(s) attached thereto. The preparation of a methylene compound useful as a precursor to an electron deficient olefin is depicted in FIG. 2, which illustrates the esterification of cyanoacetic acid with alpha hydroxymethyl acrylate. In these compounds, the electron withdrawing substituent is selected from nitrile, carboxylic acids, carboxylic esters, sulphonic or suphinic acids or their esters, ketones, phosphocarbonyl, or nitro. Such compounds are reacted with iminium salts for example as depicted in FIG. 3 to form novel electron deficient olefins. In a desirable embodiment, these compounds have two or more electron withdrawing substituents, which may be the same or different, such as nitrile and carboxylic acid ester—in this case, a cyanoacrylate. Of course, the reactivity of these compounds in large part depends on the degree of electron withdrawing capability of the particular substituent, and the number of substituents on the active methylene carbon.
The reaction to form the novel electron deficient olefins may proceed with or without heating or cooling, depending of course on the specific reactants and the scale of the reaction. Decomposition of the source of formaldehyde, e.g., paraformaldehyde, may occur under gentle heating up to a temperature of about 70° C., to liberate formaldehyde in situ in the reaction medium. The temperature may be reached through an external heating element or internally by means of the exotherm that may be generated, depending of course on the identity of the reactants. The temperature of the reaction should be controlled however to accommodate any such exothermic processes.
The time of reaction may be monitored by reference to the formation of the desired novel electron deficient olefin product. A ¹H NMR spectrometer is a particularly useful tool in this regard. The time of reaction may be as little as 1 minute, for instance, or longer or shorter for that matter depending again on the identity of the specific, reactants, the scale of the reaction and whether heat is introduced to or removed from the reaction conditions.
Once formed, the novel electron deficient olefin may be isolated by direct distillation under vacuum out of the reaction mixture or by freezing it in a solid form and separating off the liquid phase.
The novel electron deficient olefin may be stabilized during the synthesis and/or isolation procedure, and also in the isolated product to improve its shelf life. Suitable stabilizers include stabilizer packages that may contain one or more of free radical stabilizers and acidic stabilizers.
For example, free radical stabilizers include hydroquinone, pyrocatechol, resorcinol or derivatives thereof, such as hydroquinone monoethyl ether, or phenols, such as di-t-butylphenol or 2,6-di-t-butyl-p-cresol, 2,2′-methylene-bis-(4-methyl-6-t-butylphenol), bisphenol A, dihydroxydiphenylmethane, and styrenized phenols.
For example, acidic stabilizers include sulfuric acid, hydrochloric acid, sulfonic acids, such as methane, ethane or higher sulfonic acids, p-toluene sulfonic acid, phosphoric acid or polyphosphoric acids, silyl esters of strong acids, such as trialkyl chlorosilanes, dialkyl dichlorosilanes, alkyl trichlorosilanes, tetrachlorosilane, trialkyl silylsulfonic acids, trialkyl silyl-p-toluene sulfonates, bis-trialkyl silylsulfate and trialkyl silylphosphoric acid esters.
The amount of either stabilizer used to stabilize the electron deficient olefin prepared by the inventive processes is well known to those of ordinary skill in the art, and may be varied depending on the properties of the resulting composition made from the so formed electron deficient olefin.
The present invention also provides compositions of the compounds of structures I, II or III, together with a stabilizer package comprising at least one of a free radical stabilizer and an anionic stabilizer; and optionally, one or more additives selected from cure accelerators, thickeners, thixotropes, tougheners, thermal resistance-conferring agents, or plasticizers.
The cure accelerators that may be included with the inventive electron deficient olefins to form inventive compositions include calixarenes and oxacalixarenes, silacrowns, crown ethers, cyclodextrins, poly(ethyleneglycol) di(meth)acrylates, ethoxylated hydric compounds and combinations thereof.
Of the calixarenes and oxacalixarenes, many are known, and are reported in the patent literature. See e.g. U.S. Pat. Nos. 4,556,700, 4,622,414, 4,636,539, 4,695,615, 4,718,966, and 4,855,461, the disclosures of each of which are hereby expressly incorporated herein by reference.
For instance, as regards calixarenes, those within the following structure are useful herein:
where in this connection R¹is alkyl, alkoxy, substituted alkyl or substituted alkoxy; R²is H or alkyl; and n is 4, 6 or 8.
One particularly desirable calixarene is tetrabutyl tetra[2-ethoxy-2-oxoethoxy]calix-4-arene.
A host of crown ethers are known. For instance, examples which may be used herein include 15-crown-5,18-crown-6, dibenzo-18-crown-6, benzo-15-crown-5-dibenzo-24-crown-8, dibenzo-30-crown-10, tribenzo-18-crown-6, asym-dibenzo-22-crown-6, dibenzo-14-crown-4, dicyclohexyl-18-crown-6, dicyclohexyl-24-crown-8, cyclohexyl-12-crown-4, 1,2-decalyl-15-crown-5,1,2-naphtho-15-crown-5,3,4,5-naphtyl-16-crown-5,1,2-methyl-benzo-18-crown-6,1,2-methylbenzo-5,6-methylbenzo-18-crown-6,1,2-t-butyl-18-crown-6,1,2-vinylbenzo-15-crown-5,1,2-vinylbenzo-18-crown-6,1,2-t-butyl-cyclohexyl-18-crown-6, asym-dibenzo-22-crown-6 and 1,2-benzo-1,4-benzo-5-oxygen-20-crown-7. See U.S. Pat. No. 4,837,260 (Sato), the disclosure of which is hereby expressly incorporated here by reference.
Of the silacrowns, again many are known, and are reported in the literature. For instance, a typical silacrown may be represented within the following structure:
where in this connection R³and R⁴are organo groups which do not themselves cause polymerization of the cyanoacrylate monomer, R⁵is H or CH₃and n is an integer of between 1 and 4. Examples of suitable R³and R⁴groups are R groups, alkoxy groups, such as methoxy, and aryloxy groups, such as phenoxy. The R³and R⁴groups may contain halogen or other substituents, an example being trifluoropropyl. However, groups not suitable as R⁴and R⁵groups are basic groups, such as amino, substituted amino and alkylamino.
Specific examples of silacrown compounds useful in the inventive compositions include:
dimethylsila-11-crown-4;
dimethylsila-14-crown-5;
and dimethylsila-17-crown-6.
See e.g. U.S. Pat. No. 4,906,317 (Liu), the disclosure of which is hereby expressly incorporated herein by reference.
Many cyclodextrins may be used in connection with the present invention. For instance, those described and claimed in U.S. Pat. No. 5,312,864 (Wenz), the disclosure of which is hereby expressly incorporated herein by reference, as hydroxyl group derivatives of an α-, β- or γ-cyclodextrin which is at least partly soluble in the cyanoacrylate would be appropriate choices for use herein as the first accelerator component.
For instance, poly(ethylene glycol) di(meth)acrylates suitable for use herein include those within the following structure:
where n is greater than 3, such as within the range of 3 to 12, with n being 9 as particularly desirable. More specific examples include PEG 200 DMA (where n is about 4), PEG 400 DMA (where n is about 9), PEG 600 DMA (where n is about 14), and PEG 800 DMA (where n is about 19), where the number (e.g., 400) represents the average molecular weight of the glycol portion of the molecule, excluding the two methacrylate groups, expressed as grams/mole (i.e., 400 g/mol). A particularly desirable PEG DMA is PEG 400 DMA.
And of the ethoxylated hydric compounds (or ethoxylated fatty alcohols that may be employed), appropriate ones may be chosen from those within the following structure:
where C_mcan be a linear or branched alkyl or alkenyl chain, m is an integer between 1 to 30, such as from 5 to 20, n is an integer between 2 to 30, such as from 5 to 15, and R in this connection may be H or alkyl, such as C_1-6alkyl.
Commercially available examples of materials within the above structure include those offered under the DEHYDOL tradename from Henkel KGaA, Dusseldorf, Germany, such as DEHYDOL 100.
When used, the cure accelerator should be included in the compositions in an amount within the range of from about 0.01% to about 10% by weight, with the range of about 0.1 to about 0.5% by weight being desirable, and about 0.4% by weight of the total composition being particularly desirable.
Other additives may be included with the inventive electron deficient olefins to form inventive compositions to confer additional physical properties, such as improved shock resistance, thickness (for instance, polymethyl methacrylate), thixotropy (for instance fumed silica), color, and enhanced resistance to thermal degradation [for instance, maleimide compounds such as N,N′-meta-phenylene bismaleimide (see U.S. Pat. No. 3,988,299 (Malofsky)), certain mono, poly or hetero aromatic compounds characterized by at least three substitutions on an aromatic ring thereof, two or more of which being electron withdrawing groups (see U.S. Pat. No. 5,288,794 (Attarwala)), certain quinoid compounds (see U.S. Pat. No. 5,306,752 (Attarwala)), certain sulfur-containing compounds, such as an anhydrosulfite, a sulfoxide, a sulfite, a sulfonate, a methanesulfonate or a p-toluenesulfonate (see U.S. Pat. No. 5,328,944 (Attarwala)), or certain sulfur-containing compounds, such as a sulfinate, a cyclic sultinate naphthosultone compound substituted with at least one strong electron withdrawing group at least as strongly electron withdrawing as nitro (see U.S. Pat. No. 5,424,343 (Attarwala)), and alkylating agents such as polyvinyl benzyl chloride, 4-nitrobenzyl chloride, and combinations thereof, silylating agents, and combinations thereof (see U.S. Pat. No. 6,093,780 (Attarwala)), the disclosures of each of which are hereby incorporated herein by reference. Such additives therefore may be selected from certain acidic materials (like citric acid), thixotropy or gelling agents, thickeners, dyes, thermal degradation resistance enhancers, and combinations thereof. See e.g. U.S. patent application Ser. No. 11/119,703 and U.S. Pat. Nos. 5,306,752, 5,424,344 and 6,835,789, the disclosures of each of which are hereby incorporated herein by reference.
These other additives may be used in the inventive compositions individually in an amount from about 0.05% to about 20%, such as about 1% to 15%, desirably 5% to 10% by weight, depending of course on the identity of the additive. For instance, and more specifically, citric acid may be used in the inventive compositions in an amount of 5 to 500 ppm, desirably 10 to 100 ppm.
Of course, the molecular design of the inventive electron deficient olefins may render it less desirable to include one or more these additives with the inventive electron deficient olefins to form inventive compositions.
The present invention further provides compositions of the inventive compounds, together with a cyanoacrylate, a methylidene malonate or combinations thereof.
More specifically, the cyanoacrylate used in combination with the inventive compounds is one within structure IV:
where in this connection R¹is selected from C_1-16alkyl, alkoxyalkyl, cycloalkyl, alkenyl (such as allyl), alkynyl, arylalkyl, aryl, or haloalkyl groups.
The cyanoacrylate with structure IV is selected from methyl cyanoacrylate, ethyl-2-cyanoacrylate, propyl cyanoacrylates, butyl cyanoacrylates, octyl cyanoacrylates, allyl cyanoacrylate, β-methoxyethyl cyanoacrylate and combinations thereof.
The methylidene malonate used in combination with the inventive compounds is one within structure V:
where in this connection R²and R³are each independently selected from C_1-16alkyl, alkoxyalkyl, cycloalkyl, alkenyl, aralkyl, aryl, allyl or haloalkyl groups.
The present invention further provides compositions of certain of the compounds of structure I, together with a coreactant, such as one selected from epoxides (such as cycloaliphatic epoxies), episulfides, oxetanes, thioxetanes, dioxolanes, dioxanes, isocyanates, maleimides, oxazolines, (meth)acrylates, acrylamides, cyanoacrylates, methylidene malonates or vinyl ethers. Particularly desirable compounds within structure I for this purpose include
The following examples are intended to illustrate but in no way limit the present invention.

Examples

Example 1

PRIMENE 81-R imine was prepared by reaction of PRIMENE 81-R amine with a stoichiometric equivalent of paraformaldehyde and removal of water of condensation. All imines formed were distillable liquids and existed in stable monomeric imine forms as confirmed by ¹H NMR 60 MHz (CDCl₃) 2H s (br) 7.45 ppm and FTIR (1650 cm⁻¹).

Example 2

PRIMENE 81-R iminium-MSA was prepared from PRIMENE 81-R imine by adding dropwise with stirring methane sulfonic acid at ice water bath temperature, yielding a pale yellow iminium salt.

Example 3

To a stirring mixture of cyanoacetic acid (90 g, 1.05 mol), ethyl 2-hydroxylmethyl acrylate (130 g, 1.0 mol), p-toluene sulfonic acid (500 mg) and hydroquinone (200 mg), was added toluene (150 mL), and the mixture was refluxed at a temperature of 150° C. to azeotropically remove water.
After cooling, the reaction product was washed consecutively with 30% brine and water. The organic layer was dried over anhydrous sodium sulfate, filtered and the solvent removed by rotary evaporator. The crude reaction product was purified by vacuum distillation (120-126° C./0.2 mbar), with the ester of structure A (102 g, 0.52 mol) isolated in a 52% yield. ¹H NMR (60 MHz, CDCl₃): δ 6.39 (s, 1H), 5.89 (s, 1H), 4.90 (s, 2H), 4.28 (q, J=6.0 Hz, 2H), 3.50 (s, 2H), 1.32 (t, J=6.0 Hz, 3H); FT-IR (film): 2983.3, 2935.3, 2264.3, 1753.6, 1719.7, 1640.0, 1448.3, 1368.2, 1310.3, 1177.0, 1027.1, 817.2 cm⁻¹; GC/MS (EI) m/z (%): 198 (2) [M⁺+H], 152 (40), 129 (25), 101 (38), 85 (100), 83 (45), 68 (80).

Example 4

To a stirring solution of 2-hydroxymethylacrylonitrile (21 g, 0.25 mole) and cyanoacetic acid (20.5 g, 0.24 mole) in dry THF (0.5 l), was added a solution of dicarbodiimide (“DCC”) (51.6 g, 0.25 mole) in dry THF (100 mL) over a period of time of 30 minutes at a temperature of 0° C. The reaction mixture was stirred overnight at room temperature and the solid material that formed was filtered off and washed with dry THF. The THF was removed in vacuo, the residue dissolved in dichloromethane and the solution passed through a pad of flash silica gel (200 g). The product obtained was purified additionally by precipitation with diethyl ether from its solution in dichloromethane furnishing 30.5 grams of the ester, B in a 81% yield. ¹H NMR (250 MHz, CDCl₃): δ 3.58 (s, 2H), 4.80 (m, 2H), 6.13 (m, 1H), 6.19 (m, 1H); ¹³C NMR (62.9 MHz, CDCl₃): δ 24.4, 64.7, 112.6, 116.0, 116.8, 135.0, 162.4.

Example 5

To a stirring mixture of monoethyl malonate (5.1 g, 38.6 mmol), ethyl 2-hydroxylmethyl acrylate (5.02 g, 3.86 mmol), PTSA (50 mg) and hydroquinone (50 mg), was added toluene (50 mL) and the mixture was refluxed at a temperature of 150° C. to azeotropically remove water.
After cooling, the reaction product was washed consecutively with 30% brine and water, and the organic layer was dried over anhydrous sodium sulfate, filtered and the solvent removed by rotary evaporator. The crude reaction product was purified by vacuum distillation (98-100° C./0.1 mbar) and the ester, C was isolated in 80% yield. ¹H NMR (60 MHz, CDCl₃): δ 6.36 (s, 1H), 5.87 (s, 1H), 4.89 (s, 2H), 4.05-4.41 (m, 4H), 3.43 (s, 2H), 1.19-1.42 (m, 6H); FT-IR (film): 2984.7, 2908.6, 1735.3 (br), 1640.5, 1513,6, 1447.6, 1332.2, 1145.4, 1031.7, 817.2 cm−1; GC/MS (EI) m/z (%): 245 (2) [M⁺+H], 226 (2), 199 (20), 153 (20), 129 (70), 115 (100), 101 (40), 85 (45), 43 (65).

Example 6

To a stirring mixture of monoethyl malonate (10.18 g, 77 mmol), ethyl 2-hydroxylmethyl acrylonitrile (7.67 g, 92 mmol), conc. H₂SO₄(3 drops) and hydroquinone (1.0 g), was added toluene (50 mL) and the mixture was refluxed at a temperature of 150° C. to azeotropically remove water.
After cooling, the reaction product was washed consecutively with 30% brine and water, and the organic layer was dried over anhydrous sodium sulfate, filtered and the solvent removed by rotary evaporator. The crude reaction product was purified by vacuum distillation (86-88° C./0.05 mbar) and 7.5 g, 38 mmol of the ester, D was isolated in 49% yield. ¹H NMR (60 MHz, CDCl₃): δ 6.10 (s, 2H), 4.75 (s, 2H), 4.20 (q, J=6.6 Hz, 2H), 3.47 (s, 2H), 1.34 (t, J=6.6 Hz, 3H); FT-IR (film): 3118.1, 2986.9, 2909.0, 2230.0, 1736.0, 1629.3, 1447.3, 1371.1, 1147.8, 1033.0, 959.6 cm⁻¹; GC/MS (EI) m/z (%) : 197 (2) [M⁺], 170 (40), 152 (100), 125 (10), 115 (50), 107 (15), 87 (25), 79 (45), 66 (90), 53 (40), 43 (60).

Example 7

To a stirring mixture of PRIMENE 81-R iminium-MSA (5.86 g, 20 mmol) and cyanoacetate, A (g, 20 mmol), was added 10 mg of hydroquinone and degassed for a period of time of 5 minutes at room temperature. Immediately thereafter, the degassed stirring mixture was vacuum distilled (0.2 mbar) at a temperature of 200° C. The cyanoacrylate ester, E was collected as a colourless oil (60% purity by GC, 36% yield). ¹H NMR (60 MHz, CDCl₃): δ 7.01 (s, 1H), 6.58 (s, 1H), 6.36 (s, 1H), 5.88 (s, 1H), 4.95 (s, 1H), 4.27 (q, J=6.6 Hz, 2H), 1.30 (t, J=6.6 Hz, 3H); FT-IR (film): 3125.4 (C═C), 2937.7, 2875.0, 2238.3 (CN), 1723.8 (b, s, CO), 1641.6 (C═C), 1389.2, 1310.6, 1155.5, 1026.7, 803.6 cm⁻¹.

Example 8

To a stirring mixture of PRIMENE 81-R iminium-MSA (2.93 g, 10 mmol) and the triester, C (2.44 g, 10 mmol), was added 10 mg of hydroquinone and degassed for a period of time of 5 minutes at room temperature. Immediately thereafter, the degassed stirring mixture was vacuum distilled (0.1 mbar) at a temperature of 200° C. The triester, F was collected as a colourless oil (1.7 g, 110-120° C./0.1 mbar, 43% purity by GC, 28% yield). GC/MS shows the sample is a mixture of monomer and acetate (1:1.3); ¹H NMR (60 MHz, CDCl₃): δ 6.51 (s, 1H), 6.34 (s, 2H), 5.86 (s, 1H), 4.94 (s, 1H), 4.39-4.04 (m, 4H), 1.42-1.18 (m, 6H); FT-IR (film): 2984.0, 2908.7, 1731.5, 1640.6, 1400.5, 1330.5, 1272.1, 1191.5, 1144.1, 1029.3, 813.1 cm⁻¹.

Example 9

To a stirring mixture of PRIMENE 81-R iminium-MSA (2.93 g, 10 mmol) and the diester nitrile, D (1.97 g, 10 mmol), was added 10 mg of hydroquinone and degassed for a period of time of 5 minutes at room temperature. Immediately thereafter, the degassed stirring mixture was vacuum distilled (0.1 mbar) at a temperature of 200° C. The diester nitrile, G was collected as a colourless oil (1.7 g, 94-104° C./0.25-0.35 mbar, 80% purity by GC, 65% yield). ¹H NMR (60 MHz, CDCl₃): δ 6.62 (s, 2H), 6.12 (s, 2H), 4.81 (s, 2H), 4.26 (q, J=6.0 Hz, 2H), 1.33 (t, J=6.0 Hz, 3H); FT-IR (film): 3118.4, 2985.8, 2229.9, 1736.1, 1628.7, 1407.3, 1371.9, 1331.0, 1191.8, 1030.2, 805.9 cm⁻¹.

Example 10

To a stirring mixture of PRIMENE 81-R iminium-MSA (2.93 g, 10 mmol) and the dinitrile ester, B (1.50 g, 10 mmol), was added 10 mg of hydroquinone and degassed for a period of time of 5 minutes at room temperature. Immediately thereafter, the degassed stirring mixture was vacuum distilled (0.2 mbar) at a temperature of 200° C. The dinitrile ester, K was collected as a colourless oil (0.96 g, 140-160° C./0.2-0.3 mbar, 43% purity by NMR, 25% yield). The sample was determined to contain 2-hydroxylmethyl acrylonitrile. ¹H NMR (60 MHz, CDCl₃): δ 7.04 (s, 1H), 6.64 (s, 1H), 6.12 (s, 2H), 4.82 (s, 2H); FT-IR (film): 3124.9, 2960.9, 2874.6, 2229.5, 1745.0, 1678.1, 1528.9, 1284.3, 1177.4, 955.0, 802.5 cm⁻¹.
The table below shows the starting intermediate, the resulting electron deficient olefin, the purity of the resulting electron deficient olefin and the yield in which some of the electron deficient olefins described above were obtained.

TABLE 1

	Electron Deficient	Purity	Yield
Intermediate	Olefin	by GC (%)	(%)

		60	36

		43	28

		80	65

		43	25

Claims

1. Compounds embraced by structure I

wherein X is (a) an electron withdrawing group, or (b) Y;

Y is

wherein D is a member selected from the group consisting of H, alkyl and aryl,

Z is either

(i)

wherein Q is

a. an electron withdrawing group or

b. a first reactive functionality, or

(ii) a second reactive functionality, g is 1-10; and

n is 0 or 1.

2. Compounds according to claim 1, wherein X is an electron withdrawing group selected from the group consisting of CN, CO₂R, CO₂H, COCl, COR, COPO(OR)₂, COPOR₂, SO₂R, SO₃R and NO₂, wherein R is C_1-4.

3. Compounds according to claim 1, wherein Y is

wherein D is a member selected from the group consisting of H, alkyl and aryl, Z is

wherein Q is an electron withdrawing group selected from the group consisting of CN, CO₂R, CO₂H, COCl, COR, COPO(OR)₂, COPOR₂, SO₂R, SO₃R and NO₂, wherein R is C_1-4, and g is 1.

4. Compounds according to claim 1, wherein Y is

wherein Q is a first reactive functionality selected from the group consisting of amides and thioamides and g is 1.

5. Compounds according to claim 1, wherein Y is

wherein D is a member selected from the group consisting of H, alkyl and aryl, Z is a second reactive functionality selected from the group consisting of epoxides, episulfides, oxetanes, thioxetanes, dioxolanes, dioxanes, isocyanates, maleimides, oxazolines, succinimides, 2-cyanoacrylates, methylidene malonates, acrylonitrile, (meth)acrylates, carboxylic acids and derivatives thereof, cyanoacetates, methylene malonates, hydroxyls, silanes, siloxanes, titanates, and zirconates, and g is 1.

6. Compounds according to claim 1, embraced by structure II

wherein X is an electron withdrawing group or E, E is as shown,

is a reactive functionality, D is a member selected from the group consisting of H, alkyl and aryl, n is 0 or 1, g is 1, and A, B, 1, 2, 3, 4, 5, and 6 are each references to bond designations.

7. Compounds according to claim 1, embraced by structure III

wherein X is an electron withdrawing group or F, D is a member selected from the group consisting of H, alkyl and aryl, Z is a reactive functionality, n is 0 or 1 and g is 1.

8. Compounds according to claim 7, wherein Z is a second reactive, functionality selected from the group consisting of epoxides, episulfides, oxetanes, thioxetanes, dioxolanes, dioxanes, isocyanates, maleimides, oxazolines, succinimides, 2-cyanoacrylates, methylidene malonates, acrylonitrile, (meth)acrylates, carboxylic acids and derivatives thereof, cyanoacetates, methylene malonates, hydroxyls, silanes, siloxanes, titanates, and zirconates.

9. Compounds according to claim 1, selected from the group consisting of

10. A composition comprising:

(a) one or more compounds of claim 1;

(b) a stabilizer package comprising at least one of a free radical stabilizer and an anionic stabilizer; and

(c) optionally, one or more additives selected from the group consisting of cure accelerators, thickeners, thixotropes, tougheners, thermal resistance-conferring agents, and plasticizers.

11. The composition of claim 10, further comprising a cyanoacrylate within structure IV:

wherein R¹is selected from C_1-16alkyl, alkoxyalkyl, cycloalkyl, alkenyl, alkynyl, arylalkyl, aryl, allyl and haloalkyl groups.

12. The composition of claim 11, wherein the cyanoacrylate is selected from methyl cyanoacrylate, ethyl-2-cyanoacrylate, propyl cyanoacrylates, butyl cyanoacrylates, octyl cyanoacrylates, allyl cyanoacrylate, β-methoxyethyl cyanoacrylate and combinations thereof.

13. The composition of claim 10, further comprising a methylidene malonate within structure V:

wherein R²and R³are each independently selected from C_1-16alkyl, alkoxyalkyl, cycloalkyl, alkenyl, alkynyl, arylalkyl, aryl, allyl and haloalkyl groups.

14. A composition comprising:

(a) one or more compounds of claim 9;

15. The composition of claim 14, further comprising a coreactant.

16. The composition of claim 15, wherein the coreactant is a member selected from the group consisting of epoxides, episulfides, oxetanes, thioxetanes, dioxolanes, dioxanes, isocyanates, maleimides, oxazolines, (meth)acrylates, acrylamides, cyanoacrylates, methylidene malonates, and vinyl ethers.

17. Compounds according to claim 4, wherein the amides or thioamides of Q are embraced by

C(T)NUV,

wherein T is O or S and U or V are each independently selected from H or R, wherein R is C_1-4.