KR-102963471-B1 - Cross-linked incomplete Lewis pairs as thermal triggers for the reaction of Si-H and epoxides

Abstract

The composition contains a mixture of silyl hydride, epoxide, and bridged frustrated Lewis pair.

Inventors

• 쿠르트만취, 마크-안드레
• 장, 은 실
• 웨이, 얀후

Assignees

• 다우 실리콘즈 코포레이션

Dates

Publication Date

20260513

Application Date

20200602

Priority Date

20190604

Claims (10)

1. A composition comprising a mixture of silyl hydride, epoxide, and bridged frustrated Lewis pair.
2. In claim 1, the cross-linked incomplete Lewis pair is (a) A Lewis acid selected from the group consisting of aluminum alkyl, aluminum aryl, fluorinated aryl borane, boron halide, aluminum halide, gallium alkyl, gallium aryl, gallium halide, silyllium cation and phosphonium cation; (b) Lewis bases selected from the group consisting of molecules having the following structures: PR3 , P( NR2 ) 3 , NR3 , N( SiR3 ) xR3 -x , RC(NR)N, P(NR) R3 and (wherein in the above formula, R is independently selected in each case from the group consisting of hydrogen, alkyl, substituted alkyl, aryl, and substituted aryl, and x is an integer from 1 to 3); and (c) A composition comprising a crosslinking molecule connecting the Lewis acid and the Lewis base, selected from the group consisting of carbon dioxide, H₂ , nitrile, alkene, alkyne, ketone, ester, and aldehyde.
3. ◈Claim 3 was waived upon payment of the establishment registration fee.◈ A composition according to paragraph 2, wherein the Lewis acid is a fluorinated aryl borane.
4. ◈Claim 4 was waived upon payment of the establishment registration fee.◈ A composition according to paragraph 2, wherein the Lewis base is selected from the group consisting of PR3 , NR3 , guanidine, amidine, and phosphazene.
5. ◈Claim 5 was waived upon payment of the establishment registration fee.◈ A composition according to paragraph 2, wherein the crosslinking molecule is selected from the group consisting of carbon dioxide, nitrile, H₂ , alkynes, and alkenes.
6. ◈Claim 6 was waived upon payment of the establishment registration fee.◈ A composition according to claim 2, wherein the Lewis acid is a fluorinated aryl borane, the Lewis base is selected from the group consisting of PR 3 and NR 3 , the crosslinking molecule is selected from the group consisting of carbon dioxide and nitrile; and R is independently selected from the group consisting of hydrogen, alkyl, substituted alkyl, aryl, and substituted aryl in each case.
7. A composition according to claim 1, wherein the composition does not contain a transition metal.
8. (a) a step of providing a composition of any one of claims 1 to 7; and (b) heating the composition to a temperature sufficient to dissociate the Lewis acid from the cross-linked incomplete Lewis pair. A hydrosilylation method comprising
9. ◈Claim 9 was waived upon payment of the establishment registration fee.◈ A method according to claim 8, wherein step (a) comprises mixing a cross-linked incomplete Lewis pair, a silyl hydride, and an epoxide together.
10. A method according to claim 8, wherein, after step (a) and before step (b), the composition is applied to a substrate or placed in a mold.

Description

Cross-linked incomplete Lewis pairs as thermal triggers for the reaction of Si-H and epoxides The present invention relates to the use of a bridged frustrated Lewis pair as a thermal trigger for the chemical reaction between a silyl hydride and an epoxide. The bridged frustrated Lewis pair dissociates upon heating to release a Lewis acid. The Lewis acid acts as a catalyst for the chemical reaction between the silyl hydride and the epoxide. introduction An incomplete Lewis pair ("FLP") is a term referring to a pair of Lewis acids and Lewis bases in which stereocongestion prevents the Lewis acid and Lewis base from complexing or neutralizing each other. When combined, the Lewis acid and Lewis base of the FLP remain independent of each other rather than being combined and neutralized. However, FLPs have been found to be indirectly coupled to each other in the form of cross-linked incomplete Lewis pairs ("B-FLP"), where a cross-linking molecule binds to both the acid and base of the FLP to form a complex with the cross-linking molecule between the Lewis acid and the Lewis base. In some cases, the cross-linking molecule can be cleaved to produce a blocked Lewis acid and a blocked Lewis base, where a portion of the cross-linking molecule complexes with the Lewis acid and Lewis base, respectively, blocking further complexation or reaction of each. Hydrogen ( H₂ ) is an example of a cross-linking molecule that is cleaved in such a manner when forming B-FLP. B-FLP has been used to activate crosslinking molecules for use in chemical reactions. For example, hydrogen ( H₂ ) has been used as a crosslinking molecule in B-FLP to activate hydrogen for use in hydrogenation reactions (see, e.g., [JACS 2015 , 137 , 10018-10032]), and carbon dioxide has been used as a crosslinking molecule in B-FLP to activate carbon dioxide for deoxygenated hydrosilylation (see, e.g., [JACS 2010 , 132 , 10660-10661]). Other molecules used as crosslinking molecules in B-FLP to activate them for chemical reactions include nitrous oxide ( N₂O ), sulfur dioxide ( SO₂ ), alkenes, and alkynes. For example, [Angew. Chem. Int. Ed. See [2009 , 48 , 6643-6646]; [Angew. Chem. Int. Ed. 2015 , 54 , 6400-6441]; and [JACS 2015 , 137 , 10018-10032]. Discovering additional uses for B-FLP would be surprising and useful, especially if such uses enable control over chemical reactions other than those involving crosslinking molecules. The present invention provides a surprising and unexpected use for B-FLP as a thermal trigger for the addition reaction of silyl hydride (Si-H) and epoxide functional groups. Addition reactions, such as hydrosilylation reactions, typically require the presence of transition metal catalysts. However, it has been discovered that silyl hydride and epoxide functional groups undergo addition reactions in the presence of Lewis acid catalysts without the need for transition metal catalysts. Lewis acids are known to catalyze the reaction between silyl hydrides and silyl ethers in what is known as the Piers-Rubinstein ("PR") reaction. However, unlike the PR reaction, this reaction between silyl hydrides and epoxides does not require silyl ethers, nor does it produce gaseous byproducts like the PR reaction. Furthermore, the present invention offers advantages over typical addition reactions because it does not require transition metal catalysts. Similar to PR reactions, Lewis acid-catalyzed addition reactions of silyl hydrides and epoxides may be desirable for curing siloxanes in coating, adhesive, elastomer, and foaming applications. However, since epoxide/silyl hydride reactions tend to be rapid, their use requires supplying and storing the reactive system as a two-part system in which the Lewis acid catalyst is kept apart from the Si-H and/or epoxide until the reaction is required. A one-component system is easier to handle and more desirable than a two-part system, and thus the reactive components can be combined in a one-part system, but it is preferable that they do not immediately cure into a gel unless heated to a trigger temperature. Ideally, the one-part system will be storage-stable for storage or experience delayed curing at least at 23°C to increase handling time, but includes means to induce an addition reaction if desired to rapidly cure the system. There is a system for PR-reactive materials in which a Lewis acid catalyst is complexed with an ultraviolet (UV)-sensitive blocker, and the UV-sensitive blocker prevents the catalyst from enabling the PR reaction until it is irradiated with UV light. However, such a system needs to be stored in a dark place for storage stability and must be exposed to UV light to initiate curing. It may be desirable to store in a dark place and avoid the need to expose to light to induce a reaction in the system. The present invention is the result of discovering that B-FLP can be used in a silyl hydride/epoxide reaction system as a potential Lewis acid catalyst that is thermally released when heate