JPH0699391B2 - α, α-disubstituted benzylpyridinium salts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION As an initiator of a cationic polymerization reaction of a monomer capable of undergoing cationic polymerization, Friedel-Crafts catalyst such as aluminum chloride, boron trifluoride diethyl ether complex,
Light-cleavable onium salts (sulfur, selenium, tellurium) or diallyliodonium salts, and thermally-cleavable aromatic or aliphatic sulfonium salts are known. Of these, initiators that can be thermally cleaved to generate carbonium cations (thermal latent cation initiators) do not react at room temperature when used as a curing agent for one-pack type epoxy resins, for example, at temperatures above 120 ° C. Since it initiates the polymerization reaction at extremely high temperatures, it has been attracting attention as a curing agent that improves pot life and storage stability. See JP-A-58-37003 and JP-A-58-37004. However, the sulfonium salt type initiator is restricted in its use because the ionic compound produced as a by-product gives off a bad odor.

JP-A-1-96169 of the present inventors discloses a benzylpyridinium compound as a heat-latent cation initiator that does not generate a malodor. However, this compound caused a side reaction at high temperature, which caused coloring of the polymer.

The present inventors proposed a benzylammonium salt type initiator having a substituent at the α-position in Japanese Patent Application No. 1-142541, but it was cleaved because it was changed to an aliphatic or aromatic ammonium salt type instead of a pyridinium salt. The temperature was relatively high.

Therefore, an object of the present invention is to provide a thermal latent cationic initiator that does not generate a bad odor and does not color a polymer (cured product) and that is cleaved at a relatively low temperature.

DISCLOSURE OF THE INVENTION The above-mentioned problems are provided by the following formulas α, α-
Provided by a di-substituted benzylpyridinium salt.

In the formula, R ¹ , R ² and R ³ are hydrogen, halogen, alkyl, alkoxy, nitro, amino, alkylamino, cyano,
Alkoxycarbonyl or carbamoyl.

R ⁴ and R ⁵ are halogen or alkyl. R ⁶ and
R ⁷ is hydrogen, alkyl, halogen, nitro, cyano, alkoxy, amino or dialkylamino.

M is As, Sb, B or P.

X is halogen.

n is 4 when M is B, and 6 otherwise.

In the formula, the carbon number of the alkyl group (including the alkyl part of the group derived from it) is 1 to 20, preferably 4 or less.

The compound of formula (I) is prepared by reacting the corresponding α, α-disubstituted benzyl halide with pyridine or a substituted pyridine to give a pyridinium halide, the halogen anion of which is MX.
n ^- it can be synthesized by exchanging.

The compound of formula (I) is cleaved when the temperature increases to give the corresponding carbonium cation, To initiate a polymerization chain reaction of cationically polymerizable monomers such as olefins, vinyl ethers, styrene derivatives, dienes, carbonyl compounds, cyclic ethers, epoxides, cyclic esters and cyclic amides. However, it is almost inactive at room temperature, but since it functions as an initiator only after heating, it is suitable for applications such as a curing agent for a one-pack type epoxy resin that utilizes its thermal potential.

In that case, the compound of the formula (I) is superior to the heat-latent type cationic curing agents proposed so far in that it does not give off a bad odor or colors a cured product and has a relatively low cleavage temperature.

Example 1 Synthesis of 1- (α, α-dimethylbenzyl) pyridinium hexafluoroantimonate α, α-dimethylbenzyl chloride 4.644 g (0.03mo)
L) and 2.373 g (0.03 mol) of pyridine were dissolved in 40 ml of methanol and reacted at 40 ° C. for 9 hours.

After completion of the reaction, the solvent was stripped off with an evaporator, water-ether was added, and unreacted substances were extracted into an ether layer to purify chloride.

Sodium hexafluoroantimonate in chloride of water layer
7.77 g (0.03 mol) was added to obtain 1- (α, α-dimethylbenzyl) pyridinium hexafluoroantimonate.

The NMR spectrum of this compound is shown below.

2.1ppm (s, 6H, Me), 7.3-7.5ppm (m, 5H, Ph), 8.0-8.2ppm
(T, 2H, Py), 8.5-8.8ppm (t, 1H, Py), 9.0-9.2ppm (d, 2
H, Py) Example 2 Synthesis of 1- (α, α-dimethylbenzyl) -4-cyanopyridinium hexafluoroantimonate From α, α-dimethylbenzyl chloride, 4-cyanopyridine and sodium hexafluoroantimonate,
The title compound was obtained in the same manner as in Example 1.

The NMR spectrum of this compound is shown below.

2.1ppm (s, 6H, Me), 7.3-7.5ppm (m, 5H, Ph), 8.7ppm (d,
2H, Py), 9.4ppm (d, 2H, Py) Example 3 Synthesis of 1- (α, α-dimethylbenzyl) -2-chloropyridinium hexafluoroantimonate α, α-dimethylbenzyl chloride, 2-chloropyridine And from sodium hexafluoroantimonate,
The title compound was obtained in the same manner as in Example 1.

The NMR spectrum of this compound is shown below.

2.1ppm (s, 6H, Me), 7.3-7.5ppm (m, 5H, Ph), 8.2ppm (t,
1H, Py), 8.4ppm (d, 1H, Py), 8.7ppm (t, 1H, Py), 9.3ppm
(D, 1H, Py) Example 4 Synthesis of 1- (α, α-dimethylbenzyl) -2-methylpyridinium hexafluoroantimonate α, α-dimethylbenzyl chloride, 2-methylpyridine and sodium hexafluoroantimonate Than,
The title compound was obtained in the same manner as in Example 1.

The NMR spectrum of this compound is shown below.

2.1ppm (s, 6H, Me), 2.8ppm (s, 3H, Me), 7.3-7.5ppm (m,
5H, Ph), 8.0-8.1ppm (m, 2H, Py), 8.5ppm (t, 1H, Py), 9.
0 ppm (d, 1H, Py) Example 5 Synthesis of 1- (α, α-dimethylbenzyl) -2-cyanopyridinium hexafluoroantimonate α, α-dimethylbenzyl chloride, 2-cyanopyridine and sodium hexafluoroantimonate From Nate,
The title compound was obtained in the same manner as in Example 1.

The NMR spectrum of this compound is shown below.

2.1ppm (s, 6H, Me), 7.3-7.5ppm (m, 5H, Ph), 8.5ppm (m,
1H, Py), 8.9ppm (m, 2H, Py), 9.4ppm (m, 1H, Py) Example 6 Synthesis of 1- (α, α-dimethylbenzyl) -4-methylpyridinium hexafluoroantimonate α, From α-dimethylbenzyl chloride, 4-methylpyridine and sodium hexafluoroantimonate,
The title compound was obtained in the same manner as in Example 1.

The NMR spectrum of this compound is shown below.

2.1ppm (s, 6H, Me), 2.7ppm (s, 3H, Me), 7.3-7.5ppm (m,
5H, Ph), 8.1ppm (d, 2H, Py), 9.0ppm (d, 2H, Py)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C08F 4/00 MFJ

Claims (1)

[Claims] 1. An α, α-disubstituted benzylpyridinium salt of the following formula: In the formula, R ¹ , R ² and R ³ are hydrogen, halogen, alkyl, alkoxy, nitro, amino, alkylamino, cyano,
Alkoxycarbonyl or carbamoyl, R ⁴ and R ⁵ are halogen or alkyl, R ⁶ and
R ⁷ is hydrogen, alkyl, halogen, nitro, cyano, alkoxy, amino or dialkylamino, M is As, Sb, B or P, X is halogen and n is 4 when M is B. And 6 in all other cases.