CA1267901A - Di-succimylimido methylamines - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A compound of the formula:

wherein R1 is selected from:

wherein n is from 2 to 12,

Description

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- 2 - 61109-7315D

PROCESS FOR THE PREPARATION OF N,N -DlMErrHYL AROMATIC
DIAMINES, INTERMEDIATES AND PRODUCTS

This application is a divisional of Serial No. 460,022, filed July 30, 1984 Inow Canadian Patent 1,2~9,298). The present application claims intermediates useful ln the preparation of N,N -dimethyl aromatic diamines.

FIELD OF THE INVENTION

This invention relates to a method and intermediates useful in the preparation of N,N -dimethyl aromatic diamines, to such compounds, and to their use as epoxy curatives, and in other applications.

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29,lC7 BACKGROUND OF THE IN~ENTIOM

DESCRIPTION OF THE PRIOR ART

Polyamines react with epoxide prepolymers to cure them by a polyaddition reaction to form tough, resinous compositions having utility as encapsulants for electronic components, adhesives, coatings, and the like.
When filled, and reinforced, e.g., with glass or graphite 10 fibers such compositions, especially those made from aromatic polyamines and epoxy prepolymers provide struc-tural composites useful where high strength and toughness are required, for example in aircraft.

Aromatic polyamines corresponding to the follow-ing general structure are generally known to be useful in such polyaddition reactions:

H2N Rl ~ NH2 O O

wherein R is S , -C- , any alkyl or aryl divalent 25 radical, and such radicals terminated, interrupted or interrupted and terminated by -O- , -S- and -N-.

Moreover, aromatic polyamines corresponding to the general formula:

R ~ -lC-Ar-MHR ) r in which R is derived from, e.g., an aliphatic diol, 35 Ar represents, e.g., phenylene and R' represents, e.a., - \

~ - 611~g 73l5 hydrogen or an alkyl radical, and r is, for example, 2, are described in U.K. Patent No. 1,182,377 ~o be use~ul to form polyaddition products with epoxide compounds haviny more than one epoxide group per molecule. Such products are disclosed to be useful as bonding agents in ~he production of moldings, coatings, laminates, especially glass-fllled lamlnates, and molding composltions. From page 3, line 117, to page 4, line 3, a distinct preference is stated for compounds wherein R is hydrogen.
In U.S. 3,932,360, diamine cured polyurethane products are described, in which the diamines are of the formula, e.g., H2N ~ -C-O-(CH2) -O-C- < ~ -NH2 wherein n is an integer from 2 to 12. This patent does not describe any N-alkyl substituted diamines.
N-methyl derivatives of such amines have now been found to comprise an important family of epoxy resin curiny agents. It is, therefore, desirable to provide a general method to prepare N-alkyl substituted diamines in light of their ability to provide,for example, epoxide polyaddition compositions with improved properties.
SUMMARY OF THE INV~NTION
The present invention seeks to provide intermediates useful in a novel general process to produce N,N -dimethyl diamine compounds.

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126~7~301 The invention of the parent appllcation seeks to provtde novel N,N -dimethyl diamine compounds, ~7htch are useful, for example, as curing agents suitable for use with compounds having more than one epoxide group per molecule.
This invention seeks to provide novel N-succinylimidomethyl diamino compounds useful a5 intermedi~tes to produce such N,N -dimethyl aromatic diamines.
To this end, the invention of the parent application provides a method for thè preparation of a bis-N-methylamino aromatic compound comprising (a) reacting the corresponding diprimary amino aromatic compound with succinimide and formaldehyde until ~ormation of the corresponding bis-N-succin.tmidyl methylamino aromatic compound is substantlally complete; and (b) trea~ing the product o~ step (a) with sodium borohydride in a solvent until formation of the bis-N-methylamino aromatic compound is substantially complete.
The invention of this divisional provides compounds of the formula: 11 I ~ ~ ~ H
CN CH2 N N-CH2-N ~
o lo wherein Rl denotes _O_/ ~ _11_~\ 0 -~-0-(CH2)n-0-C-, wherein n is from 2 to 121 The lnvention of the parent application provides compounds of the formula, ~ 7~30~L

~ ) ~ R

wherein the CH3NH- yroups are in the 4 and 4 positions and Rl representS -C-O- (CH -) - C- and n is an in~eger of from 2 to 12. These compounds provide, for example, polyaddition reaction products wlth polyepoxides having high strength and toughness.
DETAILED DESCRIPTION OF THE INVENTION
The process of the pàrent application is broadly applicable to primary aromatic polyamines. These are illustrated above by formula, wherein group Rl will be ~1~ ~ 2 ~ 1l wherein n is 2 to 6, or more preferably wherein n is 3.
Such diprimary aromatic amines are either commercially available or they can be readily prepareed by those skilled in this art.

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The di-primary amines used as certain of the starting materials are also described in the above-men-tioned U.S.

3,932,360. In general, they are prepared by reacting p-nitro-benzoyl chloride with a diol and reducing the thus formed compound to a diamine. Illustrative of suitable diols are ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. Preferred is 1,3-propanediol. The preferred diamine starting material is l,3-propanediol-bis-p-amino benzoate.
As a general procedure, succinimide is reacted with a l~ diamine to produce the corresponding and novel di-succinimido-methyl-substituted diamine. At least a stoichiometric amount of the succinimide will be used. A solven-t, such as ethanol, and heating, e.g., at temperatures of from 40C to 120C facilitate the reaction. In refluxing ethanol, formation of the di-succinimidomethyl substituted compound is substantially complete in from two to 12 hours. The product, which can be recovered by conventional methods, is generally obtained in excellent yield.
Typically, yields of greater than ~0% of theoretical are ob-tained.
In the next step of the process, the bis-succinimidomethyl compound is treated under conditions which lead to formation of the bis-N-methyl-amino compound. This is conveniently accomplished by using a combination of a borohydride and a solvent, e.g., an aprotic solvent. Typically, a mixture of sodium borohydride and dimethyl sulfoxide is used. The product is recovered in conventional ways. It is obtained in high yield.
Use of the compounds of the parent application as curing agents for epoxy resins is shown hereinafter.

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- 8 - 61lO9-73150 DESCRIPTION OF THE PREE'ERRED EMBODIMENTS
The following non-limi-ting examples illustrate the preparation of representative novel compounds of the parent and this present invention.

(a) N,N'-Disuccinimidomethyl-1,3-trimethylene-bis(p-amino-benzoate). - Two moles of succinimide are reacted with one mole of 1,3-propanediol bis-p-aminobenzoate in refluxing ethanol for hours, and the product is recovered by fil-tration after cooling, m.p. 198-200 C, yield 82~ of theoretical.
(b) N,N'-Dimethyl-1,3-trimethylene-bis-(p-aminobenzoate) - The intermediate of step (a) is treated in dimethyl sul-foxide with sodium borohydride at 85C for 1 hour. The mixture is poured into water, the product precipitates and is recovered by filtra-tion, m.p. 114C after recrystallization from methylene chloride-cyclohexane mixture, yield 84% of theoretical.

By the general procedure of Example 1, step (a), substituting the corresponding diprimary amines, the following di-N-succinimidomethyl amines can be provided':

O O

¢N-CH2-N-~-O- ( CH2 )1l-O-C<~}N-CH2-7~

wherein n is, respectively, 2, 4, 5 and 6.

By the general procedure of Example 1, step (b), substituting the corresponding N-succinimido-methyl amines, the following N-methyl amines can be obtained:

CH3NH ~ (C 2)n C ~ NHC~3 wherein n is, respectively, 2, 4, 5, and 6.

(a) N,N'-Disuccinimidomethyl-4,4'-bis(p-aminophenoxy) diphenyl sulfone. - The general procedure of Example 1, step (a) is repeated substituting for the bis-aminobenzoate compound, 4,4'-bis(p-aminophenoxy)diphenyl sulfone.

(b) N,N'-DimethYl-4~4l-bis(p-amino)diphenyl sulfone.
The procedure of Example 1, step (b), was repeated, substituting the intermediate of step (a) herein. The named product, m.p. 73-75C, was obtained.

EXP~IPLE 4 (a) N,N'-Disuccinimidomethyl-4,4'~bis(m-aminophenoxy) diphenyl sulfone. - The procedure of Example 1, step (a) is repeated, substituting 4,4'-~is(m-amino-phenoxy~
diphenyl sulfone.

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- 10 _ (b) N,N'-Dimethyl~4,4'-bis(m-aminophenoxy)diphenvl sulfone.
- The procedure of Example 1, step (b), was repeated, substituting the intermediate of step (a) herein. The named product, m.p., 63-65C, was obtained.

The products of the examples are mixed with epoxide prepolymers at 135C for 10 minutes and then degassed under vacuum. The compositions are cured by casting in a mold and cured for two hours at 135C and then for 3 hours at 180C. Physical properties are measured by ASTM D-790, Method 1 and dynamic-mechanical analysis according to ASTM D-4065. The formulations used and the results obtained are set forth in the Table:

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o I I ~r I o o o ~o o a~
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E~ ~: u~ 5 X ~ ~ h O Ul ~ Ul O ~ U~
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~ ~1 :>, ~ V o I~ I~ O
~1~t ~~1 I N ~ .C ~
U~tl tJ~ J
o _ Ia) ~ o o o ,~
c~ ~ ~ R
E~~: ~ I O IQ~ rl O
O O ~ ~ H .~C
.~ a ~ ~ ,1 ~ l ~ HU~ ~t I S E~
~1 I o ~ ~ h ~_1 - ~: ~J I OX (1)X -- C ` b~ R
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O Z rl I -~1 IS I S t ~ ~~ rl O
R ~ t Z Z z z O~ ~ O tJ~
z z z z 7~1 - 12 - 61lO9-73~50 In light of the above description, it is obvious that advantageous ~esults have been obtained with the present inven-tion. The state-of-the-art synthetic methods are limited in scope and utilize a number o-f steps, whereas the method of this invention is generally applicable and provides high yields in only two ste~s. By using the bis-methylamino compound of this inven-tion as an epoxy curative, resins can be obtained with improved strength, toughness and hot/wet properties. The new resins can be used or fiber reinforced composites where high strength and 1~ toughness are required, for example, in aerospace primary or secondary structures and other similar applications, e.g., auto-mobiles. They can also be used in adhesives.
Many variations will suggest themselves to those skilled in this art in light of the above disclosure. All such obvious variations are within the full intended scope of the appended claims.

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Claims (3)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A compound of the formula:

wherein R1 is selected from:

wherein n is from 2 to 12, , and

2. A compound of the formula:

wherein n is an integer of from 2 to 6.

3. A compound as defined in Claim 2, wherein n is 3.