GB1604697A

GB1604697A - Diamines their production and their use in the production of polyamides

Info

Publication number: GB1604697A
Application number: GB10980/80A
Authority: GB
Original assignee: Anic SpA
Current assignee: Anic SpA
Priority date: 1978-02-24
Filing date: 1978-04-24
Publication date: 1981-12-16
Also published as: IT7820560A0; IT1109546B; ES478313A1; GB1604698A; ES478314A1

Description

(54) DIAMINES, THEIR PRODUCTION, AND THEIR USE IN THE PRODUCTION OF POLYAMIDES (71) We, ANIC S.p.A., an Italian Company, of Via M. Stabile, 216, Palermo, Italy, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to diamines, their production and their use in the production of polyamides.

According to the invention, which is the subject of our parent British Patent Application No. 16146/78 (Serial No. 1,604,696), there is provided a process for producing a dinitrile having the following general formula

wherein each of R' and R2, which are the same or different, is a hydrogen atom or an aliphatic or cycloaliphatic radical, or R' and R2 together represent a divalent aliphatic radical, R3 is an aliphatic, aromatic or cycloaliphatic radical, R4 is an aliphatic or cycloaliphatic radical, and R5 is a hydrogen atom or an aliphatic, cycloaliphatic or aromatic radical, and where two of R3, R4 and R5 together may represent a divalent aliphatic radical forming with the carbon atom(s) to which it is bound a closed ring; which process comprises reacting a first nitrile having the following general formula:

wherein R' and R2 are as defined above, with an alpha, beta-unsaturated nitrile having the following general formula:

wherein R3, R4 and R5 are as defined above. That invention permits various substituted dinitriles to be obtained with good yields and selectivity.

The nitriles of formula II are, certainly when R' or R2 is other than a hydrogen atom, saturated alpha, beta-nitriles, and for the sake of convenience all the nitriles of formula II will sometimes hereafter be referred to as "alpha, beta-saturated nitriles", to distinguish them from the alpha, beta-unsaturated nitriles of formula III.

The dinitrile of formula I derives from the addition of the alpha, beta-saturated nitrile of formula II to the double bond of the alpha-beta unsaturated nitrile of formula III.

Examples of suitable alpha, beta-saturated nitriles are: acetonitrile, propionitrile, butyronitrile, isobutylronitrile, valeronitrile and, in general, the nitriles of other saturated or unsaturated, straight-chain or branched, monocarboxylic acids, cyclohexanecarbonitrile, cyclopentanecarbonitrile, cyclohexylacetonitrile, cyclopropanecarbonitrile, cyclopentylacetonitrile, 3 cyclopentyl ropionitrile, and 2' - methylcyclopent - 1' - ylacetonitrile.

Examples of suitable alpha, beta-unsaturated nitriles are: 3,3 dimethylacrylonitrile, 3,3 - diethylacrylonitrile, 2,3,3 - trimethylacrylonitrile, 1 - cyclohex- 1 - enecarbonitrile, 1 - cyclopent - 1 - enecarbonitrile, 3 methylcinnamonitrile, 2,3 - dimethylcinnamonitrile, 3,7 - dimethylocta - 2,6 - dienenitrile ("geranonitrile"), and cyclogeranonitrile.

Thus, by reacting various alpha, beta-saturated nitriles with various alpha, beta-unsaturated nitriles, there can be obtained a variety of dinitriles which are useful, particularly after their hydrogenation to the corresponding diamines, in the synthesis of amorphous polyamides.

Examples of dinitriles which can be obtained by the process according to the invention of our parent Application No. 16146/78 (Serial No. 1,604,696), are:

Of these five compounds, only the last is known from the literature.

The reaction for producing the dinitriles, according to the invention of our parent Application No. 16146/78 (Serial No. 1,604,696), is preferably effected by contacting the alpha, beta-saturated nitrile with a strong base, whereafter there is added to the resulting mixture the alpha, beta-unsaturated nitrile. A few minutes after the addition of the alpha, beta-unsaturated nitrile, the reaction may be stopped by the addition of ammonium chloride. The dinitrile produced may be separated according to a conventional procedure; for example, after having evaporated off the solvent, water may be added and the extraction then effected by means of a water-immiscible solvent. The dinitrile which has been extracted in this way may possibly be purified by distillation under reduced pressures.

As regards the stoichiometry of the reaction, the alpha, beta-saturated and a,-unsaturated nitriles may, if desired, be used in equimolar amounts. The two reactants can be used as such or diluted by an inert solvent such as diethyl ether, tetrahydrofuran or a hydrocarbonaceous solvent. The strong bases which can be used are preferably the amides of alkali metals, such as sodamide, potassium amide or lithium amide; the hydrides of alkali metals or of alkaline earth metals, such as sodium hydride, lithium hydride, potassium hydride and calcium hydride; and metal alkyls such as lithium n-butyl and lithium isopropyl.

The strong bases listed above desirably are in an at least equimolar amount relative to each of the alpha, beta-saturated nitriles, and the ap-unsaturated nitriles and thus, as a general rule, they are within the range of from 1 to 5 moles of base per mole of saturated nitrile, preferably from 1 to 1.8 moles per mole of saturated nitrile. It is possible, obviously, to adopt a ratio below the 1:1 molar ratio but this can result in not only a lower yield but also a fall in selectivity caused by the formation of undesirable products.

When strong bases are used they can be preformed or formed "in situ"; for example, sodamide can be obtained by introducing elemental sodium in ammonia in the presence of an appropriate catalyst.

It is advisable to use a solvent which is capable of dissolving, at least in part, any strong base present. For example, for the amides of alkali metals, it is preferable that ammonia be used, whereas for the lithium alkyls it is preferred that diethyl ether, hexane or tetrahydrofuran be used. Understandably it is not appropriate to use, as the solvent, a substance which would interfere with the basic substance, such as an acid or ester.

The reaction proceeds rapidly, even at temperatures below 0 C, so that there is no need to raise the temperature in order to increase the reaction rate. The reaction generally takes place in the range from -800C to +700C, the range from -500C to --100C being preferred. In the presence of the strong base, the reaction progresses through three discrete stages.

In the first stage of the preferred embodiment indicated above, the alpha, beta-saturated nitrile is contacted with the strong base, to form an anion of the a saturated nitrile.

In the second stage, there is added to the resulting mixture the alpha, betaunsaturated nitrile, thus enabling the anion of the alpha, beta-saturated nitrile (formed in the first stage), to react with and be added to the double bond of the alpha, beta-unsaturated nitrile.

The third stage involves stopping the reaction with an acid, or with a salt of a strong acid and a weak base, preferably ammonium chloride, which neutralizes the anion and produces the desired dinitrile. For convenience, reference will hereafter be made to the case in which ammonium chloride is used, but it will be appreciated that what is stated in respect of ammonium chloride also applies to the acid or to the salt of the strong acid and weak base.

When using a strong base, the reaction can be regarded as a sequence of three orderly subsequential stages, and thus the order for the addition of the nitriles is fixed. Thus, conveniently, the alpha, beta-saturated nitrile is introduced into the reactor, and, after reaction of that nitrile with the base, the alpha, beta-unsaturated nitrile is poured into the reaction mixture. As regards the reaction times, the first stage, i.e. the ionization of the alpha, beta-saturated nitrile, usually takes from 10 minutes to 100 minutes, and more frequently it takes from 20 minutes to 40 minutes.

The second stage, i.e. the reaction of anion of the alpha, beta-saturated nitrile with the alpha, beta-unsaturated nitrile, requires preferably, between the completion of the addition of the alpha, beta-unsaturated nitrile and the reaction with ammonium chloride, a time of from 1 minute to 60 minutes, more preferably from 3 minutes to 10 minutes.

Ammonium chloride is generally to be used in a molar quantity equal to or greater than that of the strong base, preferably in a molar ratio of ammonium chloride to strong base of 1:1 to 5:1. Usually, it is sufficient to use from 1.1 to 2 moles of ammonium chloride per mole of base used.

Ammonium chloride may be poured cautiously into the reaction mixture: as an alternative, it is preferred to siphon the reaction mixture into an externally cooled vessel which contains ammonium chloride: the latter can be solid, or dissolved or slurried in an inert solvent, for example dissolved in water or slurried in diethyl ether.

The reaction is largely unaffected by pressure therefore it can be performed either at atmospheric pressure or at a greater pressure.

The present invention relates to the use of 1,5-dinitriles in the production of 1,5-diamines. Thus, the present invention provides a process for producing a diamine having the following general formula:

wherein R', R2, R3, R4 and R5 are as defined above, which process comprises hydrogenating, in the pressure or absence of a catalyst, a dinitrile having the following general formula:

wherein R', R2, R3, R4 and R5 are as defined above.

Diamines are useful in the production of polyamides, and there are many patents and publications which relate to the synthesis of transparent polyamides. A principal process for producing such polymers is the polycondensation of a particular class of aliphatic diamines, in fact the diamines of which the main chain Is substituted by one or more alkyl groups. The polyamides obtained therefrom generally show a very low crystallinity and very often they are wholly amorphous, thus they are transparent. This phenomenon is an outcome of the steric hindrance caused by the presence of the alkyls.

The substituted aliphatic diamines which are best known from the literature are: 2,2,4-trimethyl- and 2,4,4trimethyl hexamethylenediamine which may be derived from isophorone; 3 - aminomethyl - 3,5,5 - trimethylcyclohexylamine which ma also e derived from isophorone; a mixture of diamines based on trimmers of cyclopentadiene; and 2,2dimethyl pentadiamine. These diamines, however, cannot be obtained in a convenient and cheap manner; in fact, their production involves a series of reactions which sometimes use toxic reagents such as hydrogen cyanide.

When the process according to the present invention for producing a diamine is effected in the presence of a catalyst, the catalyst is preferably palladium, platinum, rhodium or ruthenium, which can be used in the pure state or in the state of an oxide and otherwise, and which may be unsupported or may be deposited on an inert supporting member such as activated carbon or alumina. Other suitable catalysts can be other metals of Group VIII of the Periodic Table, such as nickel, Raney nickel, cobalt, and Raney cobalt.

The working conditions are generally selected as a function of any catalyst which is adopted. In the case in which the catalyst is a noble metal, there is preferably used as the solvent an aliphatic carboxylic acid such as acetic acid or propionic acid, acetic acid being, however, preferred.

There can be used other solvents, such as, in the case of rhodium, an ammoniacal solution.

The temperature at which the reduction is carried out is generally, but not necessarily, in the range from 10 C to 1500C, room temperature being preferred.

The reduction, moreover, can be conducted under a wide range of pressures of hydrogen, from values near atmospheric pressure to 300 atmospheres, preferably from 30 to 150 atmospheres. When the catalyst employed is a metal of Group VIII of the Periodic Table such as Raney cobalt, or Raney nickel, the presence of a solvent is not essential, although it is preferred to work with a diluent such as ethanol or dioxan in variable proportions. It is preferred to work in the presence of ammonia, so as to minimize the formation of secondary and tertiary amines. The quantity of ammonia to be used is preferably from 5 to 20 moles per mole of dinitrile. The reduction is preferably carried out at a temperature of from 10 C to 150 C, more preferably from 60 to 150"C, and under a hydrogen pressure of from I to 700 atmospheres, more preferably from 120 to 450 atmospheres.

The hydrogenation of compound (I) may alternatively be carried out without any catalyst, for example when using sodium and alcohol, or diborane. The resulting diamines having the general formula IV can be used with advantage not only for the synthesis of polyamides, on the properties of which a discussion will be made hereinafter, but also as stabilizers or anti-oxidants for lubricant oils, as agents for treating polyepoxides, and as intermediates for the synthesis of the corresponding isocyanates.

A second divisional application No. 8010981 (Serial No. 1,604,698) of the parent Application No. 16146/78 (Serial No. 1,604,696) provides a process for producing an amorphous polyamide, which is transparent, by polycondensing a diamine of the formula IV above with a dicarboxylic aliphatic, cycloaliphatic or aromatic acid or a derivative of the same, such as a salt, ester or halide (e.g.

chloride. The use of a diamine produced by the present invention in the production of such a polyamide constitutes a further aspect of the present invention.

For the synthesis of these novel polaymides, conventional polycondensation techniques can be adopted. It is possible, for example, to heat together the diamine and the diacid, as such or in the form of salts, with water or in an anhydrous environment, with no oxygen being present, and at temperatures and pressures which are preferably high, and to complete the polycondensation by heating, for example, in vacuum to dispel the water produced. As a modification, a salt can be heated in an inert solvent such as m-cresol. In order that the molecular weight of the polymer may be limited, a slight excess of the diamine or the diacid can be employed, or there can be added a reagent capable of forming a monofunctional amide bond, such as acetic acid. The same reaction can likewise be effected between the diamine and a diester of the dicarboxylic acid. Methods of interface polycondensation can also be adopted by reacting a dichloride of a dicarboxylic acid, dissolved in a water-immiscible organic solvent, with an aqueous solution of a diamine which contains another proton acceptor. Various solvents can be used, such as benzene, toluene, chloroform, methylene chloride and carbon tetrachloride. As proton acceptors there can be used the diamine itself, a tertiary organic base such as triethylamine, a mineral base such as calcium hydroxide, or the solvent itself if this is an amide, for example bimethyl acetamide.

Examples of suitable dicarboxylic acids are glutaric acid, adipic acid, monomethyladipic, dimethyladipic and trimethyladipic acids, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tetradecanedioic acid, octadecanedioic acid, 3-ethylsebacic acid, 3-butylsuberic acid, cyclohexane - 1,4 - dicarboxylic acid, cyclopentane - 1,3 - dicarboxylic acid, isophthalic acid, 4-methylisophthalic acid, terephthalic acid, 2methylterephthalic acid, and naphthalenedicarboxylic acids.

Examples of suitable chlorides of the diacids are o-phthaloyl chloride, methoxy-, dimethoxy- or ethoxy-isophthaloyl chloride, terephthaloyl chloride, 2,5 - dibromoterephthaloyl chloride, and the acid chlorides of succinic, adipic and sebacic acids.

Examples of suitable esters are diethyl oxalate, dibutyl oxalate, butyl phenylmalonate, and the methyl and phenyl diesters of (i) ortho-, iso- and terephthalic acids, (ii) pyridine - 2,5 - dicarboxylic acid and (iii) furan - 2,5 dicarboxylic acid.

Another aspect of the invention of our second divisional Application No.

8010981 (Serial No. 1,604,698) is a process for producing copolymers by reacting one or more of the dicarboxylic acids or of their derivatives, with two or more diamines, at least one of the latter diamines being of the general formula IV.

For example, a dicarboxylic acid, its diester or its dichloride can be reacted with one of the diamines according to the present invention, the latter diamine being admixed with another diamine such as hexamethylenediamine, copolyamides being thus obtained which exhibit interesting properties.

The polyamides prepared according to the process of the invention of the second divisional Application No. 8010981 (Serial No. 1,604,698) generally exhibit a good solubility in m-cresol, dimethylsulphoxide and dimethylformamide. These polyamides are swollen by chloroform and by ethanol and, sometimes, in certain cases of aliphatic polyamides, they are dissolved by these solvents. They are generally unaffected by acetone, diethyl ether and petroleum ether. Depending on the particular dicarboxylic acid which is used, the polyamides according to that invention display a glass transition (Tg) which lies within a wide temperature range.

Of particular interest are the polyterephthalamides, which have a high Tg and thus a good dimensional stability which enables them to be used even at comparatively high temperatures.

So far as we are aware, all the polyamides of that invention are amorphous, as shown by X-ray analysis performed on the polymers as such, as well as on the annealed polymers. Thermal analysis of these samples, performed by differential scanning calorimetry (D.S.C.), in addition to indicating the Tg, shows that the polyamides of that invention are thermally stable since they do not display any appreciable sign of decomposition at temperatures up to 300"C. The polyamides have been characterized, in addition, by measuring their water absorptivity and inherent viscosity (inh. ii) at 1300C in a 0.5% solution in 98% H2SO4.

The attitude of these polyamides towards film formation, their good adhesion to glass and to certain metals, their good solubility in a few organic solvents and their transparency (attributable to their amorphous structure) suggest the exploitation of such polyamides in the lacquer and varnish industry and, above all, in the manufacture of molded transparent articles.

To provide a better understanding of the present invention, the following examples are given by way of illustration, Examples 1 to 5 illustrating the production of dinitriles, Examples 6 and 7 illustrating the production of diamines and Examples 8 and 9 illustrating the production of polyamides.

EXAMPLE 1 Preparation of 2,3,3-Trimethyl-Pentane Dinitrile of Formula

A one-litre flask, equipped with mechanical stirrer having glass vanes, and a dropping funnel with a nitrogen inlet and an inlet for ammonia, was charged under a nitrogen atmosphere with 300 ml of liquid ammonia which had been carefully dehydrated by a first pass over potassium hydroxide pellets and then by a second pass over finely crushed elemental sodium.

During the introduction of ammonia and during the remainder of the reaction, the flask was immersed in a bath of alcohol and dry ice, the temperature of the bath being constantily maintained in the range -41"C to -380C.

Meanwhile, in a weighing jar containing anhydrous hexane, there were prepared 5.06 grams (0.22 mole) of elemental sodium in tiny fragments.

The reaction flask was then charged, with stirring and under a slight stream of anhydrous nitrogen, with a pinch of ferric chloride (about 200 milligrams) and then with one tenth of the metallic sodium which had been prepared beforehand.

After 10 minutes the flask was charged with the remaining sodium pieces, an operation which took 10 minutes approximately.

After an additional 15 minutes there were poured into the flask over the course of 5 minutes, 11 grams (0.2 mole) of anhydrous propionitrile diluted with 20 ml of anhydrous diethyl ether.

After a pause of 30 minutes there were added, over the course of 5 minutes, 16.2 grams (0.2 mole) of 3,3-dimethyl acrylonitrile of commerical purity (i.e. 95%) diluted with 20 ml of an hydros diethyl ether.

5 Minutes after the completion of the addition of the 3,3-dimethyl acrylonitrile, the reaction mixture was siphoned into an Erlenmeyer flask which contained 22.4 grams (0.4 mole) of ammonium chloride slurried in 150 ml of diethyl ether; the flask had a magnetic stirrer and was cooled externally by an alcohol and dry ice bath.

Ammonia was then evaporated off by immersing the flask in a crystallizer filled with alcohol. During evaporation, there were added about 150 ml of diethyl ether, whereafter, on completion of the evaporation of ammonia, 150 ml of water were added. The two phases were then separated. The aqeuous phase was extracted six times with dimethyl ether (50 ml each time). The ethereal extracts were combined, dried over anhydrous sodium sulphate and then filtered. Ether was then distilled off in a rotary evaporator under a pressure of about 20O--250 mmHg.

There were obtained 30 grams of raw product which still contain diethyl ether.

The raw product was then distilled in a vacuum in a 30-cm Vigreux column. The principal fraction was composed of 20.2 grams (yield 74.8%) of 2,3,3-trimethyl pentanedinitrile, which has a boiling point of 88"C--89"C under about 0.3 mmHg.

The most significant spectroscopic characteristics of

were: I.R.: stretching of CN at about 2250 cm-' N.M.R.: Chemical shifts relative to HMDS-CDCl3 solvent: -CH-=2.66 (q) (J=7 Hz) -CH2-=2.39 (s)

M.S.: m/e (relative intensity, %): 82(100), 55(70), 76(54), 41(40), 54(32), 39(28), 27(26), 69(20), 137(M+1)+ (3).

EXAMPLE 2 Synthesis of 3,3-Dimethylpentanedinitrile of Formula

The reaction procedure (apparatus, times, temperature, order of introduction of the reactants) was the same as described in Example 1.

The following quantities were employed: ammonia 300 ml ferric chloride 0.2 gram approx.

elemental sodium 5.06 gram (0.22 mole) acetonitrile 8.2 grams (0.2 mole) diluted with 20 ml of anh. diethyl ether 3,3-dimethylacrylonitrile 16.2 grams (0.2 mole) diluted with 20 ml of anhydrous diethyl ether.

ammonium chloride 22.4 grams (0.4 mole) slurried in 150 ml of diethyl ether.

The raw product of the reaction was processed in the manner indicated in Example 1.

There were obtained 12.2 grams (yield 50%) of 3,3-dimethyl pentanedinitrile which boiled at 95"C--96"C under a pressure of about 1.5 mmHg and solidified at room temperature.

The principal spectroscopic characteristics of this compound were: I.R.: stretching of the CN at about 2250 cm-1 N.M.R.: chemical shifts relative to HMDSCDl3 solvent KH2 =2.37 (s) -CH3=l.19 (s) M.S. m/e (relative intensity, %) 82(100), 55(49), 39(26), 41(20), 54(16), 27(14), 53(11), 29(11), 122(M+X7), 123(M+1)+(5).

EXAMPLE 3 Synthesis 3-(1-cyanocyclohexyl-3-methyl-butyronitrile of Formula

The reaction procedure apparatus, times, temperature, order of introduction of the reactants) was the same as for Example 1.

The following ingredients and amounts were employed: ammonia 300 ml ferric chloride 0.2 gram approx.

elemental sodium 5.06 grams (0.22 mole) cyclohexanecarbonitrile 21.8 grams (0.2 mole) diluted with 20 mls of anhydrous diethyl ether 3,3-dimethylacrylonitrile 16.2 grams (0.2 mote) diluted with 20 ml of anhydrous diethyl ether ammonium chloride 22.4 grams (0.4 mole) slurried in 150 ml of diethyl ether.

The raw product of the reaction was processed as described in Example 1.

There were obtained 26.6 grams (yield 70%) of 3 - (1' - cyanocyclohex - 1' yl) - 3 - methyl butyronitrile which boiled at 99 C-100 C under a pressure of 0.15 mmHg.

The principal spectroscopic characteristics of this compound were: I.R.: Stretching of the -C#N at about 2250 cm-1 N.M.R.: Chemical shifts relative to HMDSCDCl3 solvent.

CH2CN=2.50 (s)

M.S.: m/e (relative intensity, %) 109(100), 82(33), 67(19), 41(15), 110(9), 108(9), 39(8), 55(8), 191(M+1X3).

EXAMPLE 4 Synthesis of 2-ethyl-3,3-dimethyl Pentane Dinitrile of Formula

elemental sodium 5.06 gram (0.22 mole) butyronitrile 13.8 gram (0.2 mole) diluted with 20 ml of anhydrous diethyl ether 3,3-dimethylacrylonitrile 16.8 grams (0.2 mole) diluted with 20 ml of anhydrous diethyl ether ammonium chloride 16.8 grams (0.3 mole) slurried in 150 ml of diethyl ether.

The raw product of the reaction was processed as described in Example 1.

There were obtained 20.1 grams (yield 67%) of 2 - ethyl - 3,3 - dimethyl pentanedinitrile which had a boiling point of 87"C--89"C under a pressure of 0.7 mmHg.

Its principal spectroscopic characteristics were: I.R.: stretching of -CN at about 2245 cm-' N.M.R.: chemical shifts relative to HMDS - Solvent CDCI3

NCH2-=2.40 (s) CH3-CH2-=l.52 (m) approx.

CH3-C-CH3=l.l7 (s) 1.14 (s) CH3-CH2-= 1.09 (t) (J=8 Hz) M.S.: m/e (relative intensity, %) 82(100), 69(45), 54(43), 68(31), 55(31), 41(30), 110(23), 39(23), 151(M+1)+(13).

EXAMPLE 5 Synthesis of 2,3,7-trimethyl-3-cyanomethyl-6 octenenitrile of Formula

The reaction procedure (apparatus, times, temperature, order of introduction of the reactants) were the same as described in Example 1.

The following ingredients and amounts were employed.

ammonia 300 ml ferric chloride 0.2 gram approx.

elemental sodium 5.06 grams (0.22 mole) propionitrile 11 grams (0.2 mole) plus 20 ml of anhydrous diethyl ether 3,7-dimethylocta-2,6- 29.8 grams (0.2 mole) dienenitrile plus 20 ml of anhydrous diethyl ether ammonium chloride 16.8 grams (0.3 mole) slurried in 150 ml of diethyl ether.

The raw reaction product was processed as described in Example 1.

There were obtained 31 grams (yield 76%) of 2,3,7 - trimethyl - 3 cyanomethyl - 6 - octenenitrile which had a boiling point of 106"C--108"C under a pressure of about 0.05 mmHg.

Its principal spectroscopic characteristics were: I.R.: stretching of --CN at about 2245 cm-1 N.M.R.: chemical shifts relative to HMDS - Solvent CDCI3 =CH- : 5.10 (t) =CCH2 : 1.90 (m)

-CH2CN : 2.45 (d) CH2 < : about 1.45 (m)

M.S.: m/e (relative intensity, %) 69(100), 41(55), 108(34), 55(27), 94(22), 150(15), 39(12), 189(11), 204(M+X10).

EXAMPLE 6 Synthesis of 2,3,3-trimethyl Pentamethylenediamine A one-litre autoclave was charged with 40 grams of Raney cobalt (freshly prepared) and subsequently with 80 ml of absolute ethanol.

After scavenging the autoclave with nitrogen and then with hydrogen, commercial hydrogen was introduced under a pressure of 170 atmospheres and then the autoclave was heated to about 105"C for six hours. Thereafter the autoclave was cooled, the pressure was released, the autoclave was charged with a solution of 68 grams of 2,3,3 - trimethylglutaronitrile dissolved in 30 ml abs.

ethanol, the scavenging with nitrogen was repeated, there were introduced 160 grams of anhydrous ammonia, and finally commercial hydrogen was introduced under a pressure of 165 atmospheres approx. The autoclave, which was fitted with a magnetic stirrer, was heated to about 105"C--108"C, the hydrogen pressure being maintained as hydrogen was gradually absorbed. Afte 70%). The diamine was then purified by fractionation and, under a pressure of about 12 Torr, it boiled at l050C-l060C.

The principal by-product was a cyclic amine. The 2,3,3 - trimethyl - penta methylene diamine was characterized by elemental analysis, 'H.N.M.R. and '3C.N.M.R. inasmuch as mass spectrography and the infra red analysis did not prove particularly helpful.

Elemental Analysis Nitrogen Calcd. 19.4% found 19.4% N.M.R.

(Chemical shifts relative to HMDS - solvent CDCI3)

ABX 2.82.2 p.p.m. - 8 lines (1) 2) -CH2-NH2 : 2.61 p.p.m. Triplet 3) 2-NH2 : 0.95 p.p.m. Singlet (2) 4) -CH2- : 1.4+1.0 p.p.m. Triplet

1.4.1.0 p.p.m. Multiplet 6) -CH3 : 0.82 p.p.m. Doublet (8)

0.80 p.p.m. Singlet '3C.N.M.R.

Carbon atoms 1 2 3 4 5 6 & 7 8 Chemical shifts 36.9 44.6 25.4 45.5 46.1 23.9 12.2 EXAMPLE 7 Synthesis of 2-ethyl-3,3-dimethyl pentamethylenediamine By adopting the same general procedure as described in Example 6, 2 - ethyl 3,3 - dimethyl pentamethylenediamine was synthesized starting from the corresponding dinitrile.

It was characterised by 'H.N.M.R. and '3C.N.M.R.

N.M.R.

(Chemical shifts relative to HMDS - solvent CDCI,).

'H.N.M.R.

2.59+2.89 p.p.m. multiplet 1.33+1.44 p.p.m. multiplet 3) 2-NH2 : 0.984p.p.m. singlet 4) CR3- : 0.94 p.p.m. triplet

0.82=0.84 p.p.m. singlet 13C.N.M.R.

C1 : 37.6 p.p.m. triplet C2 : 42.5 p.p.m. do C3 : 35.5 p.p.m. singlet C4 : 52.7 p.p.m. doublet C8 : 21.4 p.p.m. triplet Cs : 14.4 p.p.m. quadruplet C7 . . 45.1 p.p.m. triplet C8 & C9 25.5 p.p.m. quadruplet EXAMPLE 8 Syntheses of poly-(2,3,3-trimethyl-pentamethylene)- terephthalamide A solution containing 4.54 grams (0.0315 mole) of 2,3,3 tridimethylpentamethylenediamine, purified by fractionation, and 0.0630 mole of sodium hydroxide in 2.25 litres of water, was poured into a 5-litre beaker and stirred with a high-speed stirring device.

A solution of 6.4 grams (0.0315 mole) of terephthaloyl chloride in 50 ml of methylene chloride was rapidly poured into the stirred solution. The polymerization mixture was stirred for 15 minutes at room temperature.

The resultant mixture was then filtered, and then washed with hot water, subsequently with a cold aqueous solution of sodium bicarbonate, and eventually with cold plain water. The resulting mixture was then placed in a Soxhlet extractor with ethanol and then dried in a vacuum oven at 700 C.

The resulting polymer had an inherent viscosity 17 of 0.86 (solution at 0.5 Ó conc. in 98% sulphuric acid at 30"C). X-ray analysis both on the polymer as such and on an annealed polymer (annealed at 215 C for 30 minutes) did not show any appreciable traces of crystallinity.

D.S.C. thermal analysis made it possible to identify at 175 C-178 C the glass transition and no appreciable phenomena of decomposition were experienced up to a temperature of 300 C.

EXAMPLE 9 Synthesis of poly42-ethyl-3,3-dimethyl pentamethylene) terephthalamide By adopting the same general procedure as described in Example 8, poly - (2 ethyl - 3,3 - dimethyl pentamethylene) - terephthalamide was prepared starting from 2 - ethyl - 3,3 - dimethyl pentamethylene - diamine and terephthaloyl chloride. The polymer thus obtained (inh. 'i=0.7l in a 0.5% soln. of 98% H2SO4 at 30"C) did not show on X-ray inspection any appreciable traces of crystallinity, even after annealing at 2300C for 30 minutes. DSC thermal analysis showed the glass transition to be at 1600C--1620C.

WHAT WE CLAIM IS: 1. A process for producing a diamine having the following general formula:

wherein each of R' and R2, which are the same or different, is a hydrogen atom or an aliphatic or cycloaliphatic radical, or R1 and R2 together represent a divalent aliphatic radical, R3 is an aliphatic, aromatic or cycloaliphatic radical, R4 is an aliphatic or cycloaliphatic radical, and R5 is a hydrogen atom or an aliphatic, cycloaliphatic or aromatic radical, and where two of R3, R4 and R5 together may represent a divalent aliphatic radical forming with the carbon atom(s) to which it is bound a closed ring; which process comprises hydrogenating, in the presence or absence of a catalyst, a dinitrile having the following general formula:

wherein R1, R2, R3, R4 and R5 are as defined above.

2. A process according to Claim 1, wherein the hydrogenation is effected in the presence of a catalyst comprising a metal of Group VIII of the Periodic Table, in elemental form or in the form of a compound, which catalyst is supported or unsupported.

3. A process according to Claim 2, wherein the metal of Group VIII is palladium, platinum, rhodium, ruthenium, nickel or cobalt.

4. A process according to Claim 1, 2 or 3, wherein the hydrogenation is effected at a temperature in the range from 10 to 1500C.

5. A process according to Claim 4, wherein the temperature is in the range from 60 to 1500C.

6. A process according to any one of Claims 1 to 5, wherein the hydrogenation is effected under a hydrogen pressure of from I to 700 atmospheres.

7. A process according to Claim 6, wherein the hydrogenation is effectedunder a hydrogen pressure of from 120 to 450 atmospheres.

8. A process according to any one of Claims 1 to 7, wherein the hydrogenation is effected in the presence of ammonia.

9. A process according to Claim 8, wherein there are employed from 5 to 20 moles of ammonia per mole of dinitrile of formula I.

10. A process according to Claim 1, substantially as described in either of the foregoing Examples 6 and 7.

Il. A diamine of formula IV as defined in Claim 1, whenever produced by a process according to any one of Claims 1 to 10.

12. A diamine having the following formula:

wherein R', R2, R3, R4 and R5 are as defined in Claim I, with the proviso that R', R2 and R5 are not hydrogen simultaneously, and that R3 and R4 are not simultaneously methyl groups.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. ethyl - 3,3 - dimethyl pentamethylene) - terephthalamide was prepared starting from 2 - ethyl - 3,3 - dimethyl pentamethylene - diamine and terephthaloyl chloride. The polymer thus obtained (inh. 'i=0.7l in a 0.5% soln. of 98% H2SO4 at 30"C) did not show on X-ray inspection any appreciable traces of crystallinity, even after annealing at 2300C for 30 minutes. DSC thermal analysis showed the glass transition to be at 1600C--1620C. WHAT WE CLAIM IS:

1. A process for producing a diamine having the following general formula:

wherein R1, R2, R3, R4 and R5 are as defined above.

12. A diamine having the following formula:

13. A process for producing a transparent polyamide, which comprises

condensing a diamine as claimed in Claim 11, and a dicarboxylic aliphatic, cycloaliphatic or aromatic acid or a salt, ester or halide thereof.

14. A process for producing a copolyamide, which comprises reacting one or more dicarboxylic aliphatic, cycloaliphatic or aromatic acid or a salt, ester or halide thereof, with two or more diamines, at least one of the diamines being as claimed in Claim 11.

15. A Process for Producing a copolymer which comprises reacting one or more dicarboxylic aliphatic, cycloalipfiatic or aromatic acid, or a salt, ester or halide thereof, with a diamine as claimed in Claim 11, and with hexamethylenediamine.

16. A process according to Claim 13, wherein the condensation is as described in either of the foregoing Examples 8 and 9.

17. A polyamide whenever obtained according to the process of Claim 13 or 16.

18. A copolyamide whenever obtained according to the process of Claim 14 or 15.