GB1567356A - Process for preparing lower lactams from allylac substrate - Google Patents

Description

(54) PROCESS FOR PREPARING LOWER LACTAMS FROM ALLYLIC SUBSTRATES (71) We, TEXACO DEVELOPMENT CORPORATION, a corporation organised and existing under the laws of the State of Delaware, United States of America, of 135 East 42nd Street, New York, New York 10017, United States of America, 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 the catalytic conversion of allylic substrates to cyclic lactam products.

More particularly, this invention converns processes for the synthesis of cyclic, 5-membered ring, lactams and their homologues through the carbonylation of allylic substrates, containing three or more carbon atoms, with carbon monoxide, in the presence of a catalytic amount of a homogeneous or heterogeneous rhodium catalyst. Two classes of allylic substrate may be employed in the iSnventive process, namely allylic amine substrates and allylic halides. Where the allylic substrate is an allylic halide, lactam synthesis is carried out in the presence of an amine coreactant selected from ammonia or a primary amine of I to 12 carbon atoms.

It is well documented in the literature that unsaturated compounds containing a nucleophilic group and a reactive hydrogen atom in a position which favors ring closure may react with carbon monoxide to give cyclic (ring) derivatives. This invention concerns the synthesis of 5-membered ring lactams and their homologues through the metal catalyzed carbonylation of allylic substrates. The inventive process, as described therein, may be illustrated by the carbonylation reaction of equation (I) set forth below:

wherein the desired product is a 5-membered ring lactam, the carbon valencies indicated are satisfied by hydrogen or alkyl, cycloalkyl, aryl, alkaryl or aralkyl groupings, each containing up to 12 carbon atoms, and X may be a halogen, chloride, bromide or iodide.

Alternatively, lactam synthesis may be effected from allylic amine substrates, as set forth in equation (2), wherein again the carbon valencies indicated are satisfied by hydrogen or alkyl, cycloalkyl, aryl, alkaryl or aralkyl groupings, each containing up to 12 carbon atoms.

The practice of this invention, as set forth in equation (I) and (2) is illustrated by: I) The preparation of y-butyrolactam from allylamine in the presence of carbon monoxide; 2) The synthesis of y-butyrolactam from allylic halides in the presence of carbon monoxide and ammonia.

3) The synthesis of alkyl-substituted-y-butyrolactams from allylic halides in the presence of carbon monoxide and primary alkylamines.

The lactam products of this reaction are useful generally as organic intermediates. y-Butyrolactam, and its homologues, for example, may be important in the manufacture of polyamides, and as solvents for the separation of aromatic, aliphatic mixtures.

The preparation of lactams from allylic precursors using metal carbon or carbon precursors as catalysts is described in the literature (J. Falbe and F.

Korte, Chem. Ber. 98, 1928 (1965)). Reviews by Falbe ("Carbon Monoxide in Organic Synthesis" by J. Falbe, Chapter IV, (1970)) and others summarize this work, particularly the synthesis of 5-membered ring lactams catalyzed by soluble cobalt catalysts. Unfortunately, many of these metal catalysts of the prior art have the intrinsic disadvantages of requiring stringent reaction conditions, particularly allylic isomerization and polymerization reactions. Furthermore they exhibit poor selectivity to the desired product and require the use of allylic amines as the allylic precursor (equation 2).

This invention is directed to the use of certain homogeneous and heterogeneous rhodium catalysts which exhibit improved performances in the synthesis of 5-membered ring lactams, and their homologues, from allylic precursors. In practice this class of rhodium catalyst allows lactam synthesis under significantly milder conditions of temperature and pressure than has hitherto been possible with other metal carbon catalysts of the prior art, e.g., cobalt carbon catalysts. Furthermore, the rhodium catalysts of this invention allow the formation of lactams in higher yields, with improved selectivities to desired product and higher catalyst turnover numbers than has been practical in the prior art. A further demonstrated advantage of these rhodium catalysts is that used catalyst samples remain active after carbonylation of an allylic substrate is complete. Consequently the used catalyst may be recycled with additional quantities of allylic substrate while demonstrating similar specific carbonylation activity to fresh catalyst material.

The present invention provides a process for preparing a y-lactam by reacting carbon monoxide at an elevated pressure and a temperature of at least 20 C with (i) an allylic amine or (ii) a mixture of an allylic halide, selected from allyl chlorides bromides and iodides, with at least a stoichiometric amount of amine coreactant selected from ammonia and primary amines containing I to 12 carbon atoms, wherein the reaction is carried out in the presence of a rhodium catalyst selected from Chlorobis(ethylene)rhodium(I) dimer Chlorotris(triphenylphosphine)rhodium(i) Chlorocarbonylbis(triphenylphosphine)rho Rhodium tris(acetylacetonate) Rhodium chloride plus triphenylphosphine Rhodium chloride, and said rhodium catalysts bonded to a styrene/divinylbenzene polymer with appended nitrogen or phosphorus donor groups, but excluding the use of rhodium chloride by itself in the reaction of an allylic halide with an amine co-reactant.

In order to further aid in the understanding of this invention, the following additional disclosure is submitted: Process Sequence and Variations.

In general, the components of the carbonylation reaction mixture, including optional inert solvent, allylic substrate, amine coreactant and rhodium catalyst may be added in any sequence as long as good agitation is employed throughout.

The following represent some variation insofar as the mode of catalyst addition is concerned, without departing from the inventive concept. These modifications include: a) The catalyst may be preformed and added preformed to the mixture of the other components to form the reaction mixture. b) A substantial process variation that can be employed is when the catalyst is formed in situ in one or more components of the reaction mixture.

Rhodium Catalyst.

The use of a rhodium catalyst system is essential to the inventive carbonylation process. Either heterogeneous or homogeneous reaction mixtures may be employed in the practice of this invention. In the preferred embodiment, rhodium complex catalysts which are soluble in the reaction mixture give good results. However, lactam synthesis may also be effected with catalyst which are not homogeneously distributed throughout the reaction mixture. Solid catalysts which remain in place during the course of reaction may be employed and suspensions of liquid and solid catalysts in the liquid media may also be employed.

In suitable embodiments of this invention the rhodium complex compound can be used in combination with inert material or contained or deposited on porous supports such as alumina, silica-alumina, activated charcoal, titania, zirconia, zeolites as well as zeolitic molecular seives. A preferred class of inert support for the rhodium catalysts of this invention are inert porous organic polymers.

The active form of the rhodium complex catalyst may be preformed prior to carbonylation, or it may be generated in situ.

A further useful class of rhodium catalysts for the lactam synthesis are used catalyst samples from prior preparations.

The quantity of catalyst employed is not narrowly critical and can vary over a wide range. In general the process of the invention is desirably conducted in the presence of a catalytically effective quantity of the active rhodium species which gives a suitable and reasonable reaction rate. Reaction proceeds when the rhodium concentration is as little as 0.01 mM, and even less. The upper limit is dictated and controlled primarily by economic factors in view of the exceedingly high costs of rhodium metal and its compounds. No particular advantages have been observed in using relatively high concentrations of rhodium catalyst.

Allyl Substrates.

As used throughout this disclosure, this term refers to two related classes of allylic substrate, namely allylic halides and allylic amines, wherein the unsaturation (double bond) in the substrate molecule is only between carbon-to-carbon atoms, and the halide or amine group is attached to the carbon atom one removed from the carbon atom of the double bond.

Suitable allylamine substrates have the general structure (A):

wherein the carbon valencies indicated are satisfied by hydrogen, or alkyl, cycloalkyl, aryl, alkaryl, or aralkyl groupings each containing up to 12 carbon atoms.

Illustrative of allylamines which are suitable precursors for lactam synthesis according to equation (2) include allylamine, 2-methylallylamine, l-amino-2decene, I-amino-3-ethyl-2-hexene, crotyl amine, 2-amino-3-pentene and 2-amino-2- methyl-3-butene.

When an allylic halide is the primary reaction substrate then ammonia or a primary amine must also be present in the carbonylation reaction mix in order for lactam formation to be achieved as depicted in equation (1). Suitable allyl halide substrates have the general structure (B):

wherein the carbon valencies indicated are satisfied by hydrogen, or alkyl, cycloalkyl, aryl, alkaryl, or aralkyl groupings each containing up to 12 carbon atoms.

Illustrative of suitable allyl halide precursors for lactam synthesis according to equation (1) include ally chloride, allyl bromide, ally iodide, 2-methylallyl chloride, l-chloro-2-hexene, crotyl chloride, l-bromo-2-butene, 2-methylallyl iodide, 1chloro-3-ethyl-2-hexene, 3-chloro- 1 -butene, 2-chloro-3-pentene, 1-chloro-2- decene, 3-chlorocyclohexene, and 2-chloro-2-methyl-3-butene.

Amine Coreactant.

An amine coreactant is required whenever the lactam synthesis is from an allylic halide precursor. The amine coreactants are ammonia and primary amines containing one to 12 carbon atoms, including methylamine, ethylamine, n-propylamine, cyclohexylamine, benzylamine n-hexylamine and 2ethylhexylamine.

Iodide Promoter.

Where the allylic halide precursor is an allylic chloride or bromide it is preferable to add an iodide promoter to the reaction mixture consisting of the allylic halide substrate, amine coreactant and rhodium catalyst, prior to carbonylation. Suitable iodide promoters include the alkali and alkaline earth iodides such as lithium iodide, sodium iodide, potassium iodide and calcium diiodide.

Inert Solvent.

The carbonylation process of this invention is most conveniently carried out in the presence of a liquid diluent. Suitable diluents may be inert organic diluents, or they may be reactive diluents, including the aforementioned allylic halides, allylic amines and amine coreactants, or mixtures thereof.

Illustrative of the normally liquid organic diluents which are generally suitable in the practice of this invention include, for example, saturated and aromatic hydrocarbons, e.g. hexane, octane, naphtha, cycloheptane, benzene, toluene, xylenes, or naphthalenes. N-Heterocyclic solvents such as quinoline, isoquinoline, lepidines, or pyridine, are also useful, as well as secondary and tertiary amines such as triethylamine and diethylamine. Nitriles such as acetonitrile and adiponitrile represent another class of suitable solvents for effecting the lactam synthesis.

Temperature.

The temperature required for this carbonylation process is a variable dependent upon experimental factors including the allyiic precursor employed, the pressure of carbon monoxide, the concentration and nature of the rhodium catalyst, among other things, and is at least 20"C. Generally an operating temperature range is from 200 to 250"C.

Pressure.

Superatmosphere pressures, generally of at least 10 atm., are required for substantial conversion of allyamines of the corresponding y-butyrolactams at temperatures of 20"C and above using the rhodium catalysts of this invention.

Higher pressures are oftentimes employed, while at pressures less than 10 atm., carbonylation is impractically slow.

Carbon Monoxide Environment Insofar as can be determined, the best selectivities and conversions to lactam can be obtained within a reasonable time frame by using a substantially carbon monoxide atmosphere. However, particularly in continuous operations, the carbon monoxide may be used in conjunction with from 0 to 300/n by volume of one or more inert gases such as nitrogen, argon, and neon without experiencing an unacceptable decrease in yield and conversion.

Reaction Time The time of the reaction will vary from a very short time of a few minutes or less to 24 hours or longer, depending upon the nature of the allylic substrate, the concentration and nature of the rhodium catalyst pressure and temperature.

Shorter reaction times are preferred since they give more economic processes.

Conversion As defined herein, conversion is the efficiency in transforming the allylic substrate to a non-allylic product. Conversion is expressed in mole percent and is calculated by dividing the amount of allylic substrate consumed during carbonylation by the amount of allylic substrate originally charged, and multiplying the quotient by 100.

Yield As defined herein, yield is the efficiency in catalyzing the desired carbonylation reaction relative to other undesired reaction. In this instance the formation of a 5-membered ring lactam or lactam homologue is the desired reaction. Yield is usually expressed as mole percent, and is calculated by dividing the amount of desired lactam formed by the amount of allylic halide or amine charged and multiplying the quotient obtained by 100.

Identification Procedures Where applicable, the carbonylation products of this invention are identified by one or more of the following analytical procedures, gas-liquid chromatography (glc) infrared (ir), nuclear magnetic resonance (nmr) and elemental analyses.

Unless specified all percentages are by weight rather than by volume and all temperatures are in centrigrade rather than fahrenheit.

EXAMPLE 1 Synthesis of y-Butyrolactam from Allylamine Part A To a degassed sample of allylamine (125 mmole) and toluene (75 ml) contained in a glass-lined reactor equipped for pressurizing, heating, cooling and means of agitation is added, under a nitrogen environment, 1.25 mmole of the rhodium salt, chlorocarbonylbis(triphenylphosphine)rhodium. The reactor is sealed, flushed with CO and pressured under carbon monoxide (100 atm) while heating the agitated mixture to 1200C. Pressure is adjusted to 136 atm with CO and the mixture held at temperature for 2 to 12 hours. At the end of this time, carbonylation is terminated by rapid cooling and venting of the reactor. The crude product is filtered, distilled under reduced pressure (1--10 mm Hg) to remove toluene solvent and fractionally distilled to recover the y-butyrolactam.

The crude liquid product is analyzed by GLC. Typical conversion and yield data are as follows: Allylamine conversion 95 mol. V0 y-Butyrolactam yield 67 mol. V0 Liquid recovery 99% Samples of y-butyrolactam were also recovered by preparative glc, and identified by a combination of nmr, ir, mass spec and elemental analyses.

Calcd. for C4H7NO: %C=56.5 %H=8.3 Found: %C=56.6 %H=8.4 ir C=0, 1685 Cm-1, N-H, 3240 Cm-' IHnmr (CDCI3) & 7.25 (s,lH), 3.42 (t,2H), 2.25 (t,2H), 2.13 (m,2H) Part B The synthesis of y-butyrolactam is carried out substantially as described in Part A except the reaction temperature is 80"C, and the reaction time 24 hours. y-Butyrolactam is detected in the liquid product following completion of the carbonylation step.

Part C The synthesis of y-butyrolactam is carried out substantially as described in Part A except the operating pressure of carbon monoxide is 50 atm. Again y-butyrolactam is detected in the liquid product following completion of the carbonylation step.

EXAMPLES 2 to 11 Sythesis of y-Butyrolactam from Allylamine Using Other Rhodium Catalysts Using the same type of apparatus and techniques of Example 1, ybutyrolactam is prepared from allylamine in the presence of a variety of homogeneous and heterogeneous rhodium catalysts. These catalysts include chlorobis(ethylene)rhodium(I) dimer, chlorotris(triphenylphosphine)rhodium(i), chlorocarbonybis(triphenylphosphine)rhodium(I), rhodium tris-(acetylacetonate)rhodium chloride and rhodium chloride in the presence of excess triphenylphosphine. Active heterogeneous rhodium catalyst include rhodium chloride and chlorocarbonylrhodium bonded to styrene-divinylbenzene copolymers with appended diphenylphosphine and N-cyclic groups. Table I, which summarizes the performances of said rhodium catalysts under the specified carbonylation conditions.

Of particular note, it may be seen from the data in Table I that y-butyrolactam is repeatedly synthesized here under conditions that are considerably milder than have been employed previously using the cobalt catalyst of the prior art, (J. Falbe and F. Korte, Chem, Ber. 98, 1928 (1965)). In fact by comparing the yield data in Examples 2 to 4, it may be seen that the chlorobis(ethylene)rhodium(I) dimer actually gives higher yields of y-butyrolactam at the lower carbonylation temperature of 1500C, rather than at the temperatures normally employed in syntheses of the prior art (ca. 2600 C).

Styrene-divinylbenzene polymers are diphenyl phosphinated and treated with the homogeneous rhodium catalyst of Examples 1 to 9, and the resulting catalysts are then evaluated for carbonylation of allyamine under the conditions of Example 1, Part A. In all cases the analytical procedures, confirm the formation of the desired y-butyrolactam product.

TABLE I y-Butyrolactam Synthesis from Allylamine Rhodium Temp. Pressure Time Butyrolactam Example Catalyst ( C) (atm) (hr) Yield (Mel%)a 2 Rh2Cl2[C2H4i4 150 220 12 30 3 ,, 150 136 2 23 4 ,, 260 130 2 6.8 5 Rh(CsH,O2)3b 120 136 12 28 6 RhCl[PPh3]3 50 136 2 40 7 Rh(CO)Cl[PPh3]2 150 136 2 67 8 RhCl3+2PPh3 150 190 2 22 9 RhCI3 150 190 2 35 10 RH(CO)CI/SupportC 150 136 9 2 11 RhCl5upportd 150 136 2 16 "y-Butyrolactam yield based upon allylamine charged, estimated by glc, Solvent, Toluene or Benzene, initial tCH2=CH-CH2NH2]/[Rh] = (1--2)x102, initial [Rh]=1020 mM. bRhodium acetylacetonate rhodium carbonyl chloride on styrene-divinylbenzene copolymer (2% crosslinked) with appended diphenylphosphine groups. dRhodium chloride on styrene-divinylbenzene copolymer (2% crosslinked) with appended

groups.

EXAMPLE 12 Synthesis of y-Butyrolactam from Allylamine with Rhodium Catalyst Recycle To a degassed sample of allylamine (125 mmole) and toluene (75 ml.) contained in a glass-lined reactor equipped for pressurizing, heating, cooling and means of agitation is added, under a nitrogen environment, 1.25 mmole of the rhodium salt, chlorocarbonylbis(triphenylphosphine)rhodium. The reactor is sealed, flushed with CO and pressured under carbon monoxide (100 atm.) while heating the agitated mixture to 1200C. Pressure is adjusted to 136 atm with CO and the mixture held at temperature for 2 hours. At the end of this time, carbonylation is terminated by rapid cooling and venting of the reactor. A small quantity (0.1 ml.) of the crude product is set aside for glc analyses, the remainder is distilled under reduced pressure (1--10 mm Hg) to remove toluene solvent and fractionally distilled to recover the y-butyrolactam.

The residual catalyst solution is recharged to the glass-lined reactor with fresh toluene and allylamine. Carbonylation is carried out as described supra. A third and fourth sample of allylamine are carbonylated likewise using the same catalyst solution. The results are summarized in Table II.

The data serve to confirm that samples of the chlorocarbonylbis (triphenylphosphine)rhodium(I) catalyst are active for y-butyrolactam syntheses from allylamine over at least four cycles.

TABLE II Synthesis of y-Butyrolactam from Allylamine with Rhodium Catalyst Recycle Allylic Temp Pressure Time Primary Lactam Product Reagent Rhodium Catalyst ("C) (atm) (hr) Identity Yield (Mol%) Allylamine Rh(CO)Cl(PPh3)2 150 136 2 y-Butyrolactam 67 Recycle ,, ,, ,, ,, 59 Recycle ,, ,, ,, , 40 Recycle ,, ,, ,, , 47 EXAMPLE 13 Synthesis of N-Substituted-y-Butyrolactam from Allyl Halides Part A To a degassed sample of ally chloride (125 mmole) and acetonitrile (75 ml) contained in a glass-lined reactor equipped with pressurizing, heating, cooling and means of agitation is added, under a nitrogen environment, 1.25 mmole (0.58 gm) of rhodium tris(acetylacetonate) and 4.2 gm of potassium iodide. The reactor is scaled, flushed with CO, and 8 gm of methylamine (258 mmole) is pressured in from a side ampule. The pressure is adjusted with CO to 100 atm while the agitated mixture is heated to 1200C. The pressure is further adjusted to 135 atm with CO and the mixture held at temperature for 8 hrs. At this time the carbonylation is terminated by rapid cooling and venting of the reactor. A small portion (0.1 ml) of crude product is set aside for analysis, the remainder is fractionally distilled under reduced pressure (1--10 mm Hg) to recover the solvent and N-methyl-ybutyrolactam product.

Following the fractional distillation of the crude product, the residual liquid is recharged to the pressure reactor with fresh acetonitrile solvent (75 ml), allyl chloride (125 mmole) and methylamine (8 gm, 258 mmole). Carbonylation is carried out as described supra. A third sample of ally chloride is carbonylated in a similar manner. The results including the lactam yield data, are summarized in Table III.

It is evident from the data summarized in this table that the rhodium acetylacetonate catalyst remains active after carbonylation and product recovery, and may be used to carbonylate additional quantities of allyl chloride to N-methyly-butyrolactam.

Part B The synthesis of Part A is repeated except that cobalt octacarbonyl is substituted for rhodium tris(acetylacetonate) on a mmole per mmole basis and the carbonylation is operated for 6 hrs at 2500 C. It is evident from the run data, summarized in Table III, that the N-methyl-y-butyrolactam is prepared from allyl chloride and methylamine using the soluble rhodium catalyst in greater than ten times the yield achieved with cobalt octacarbonyl, even where the temperature employed is higher for the cobalt case.

Part C The synthesis of Part A is repeated except that ally bromide is substituted for allyl chloride on a mmole-per-mmole basis. Analysis indicates that the desired Nmethyl-y-butyrolactam is present.

TABLE III Synthesis of N-Substituted-γ-Butyrolactam from Allyl Halide Reaction Reaction N-Methyl-γ-Butyrolactam Reactant Charge Rhodium Catalyst Temp( C) Time(hr) Yield(Mole %) Allyl Chloride+Methylamine Rh(C5H7O3)3+KI 120 8 27 " " Recycle " 8 30 " " " " 8 32 " " " " 12 7.5 Allyl Chloride+Methylamine Co2(CO)8 250 6 2.0 (for Comparison) EXAMPLE 14 Synthesis of y-Butyrolactam from Allyl Chloride Part A To a degassed sample of allyl chloride (125 mmole) and acetonitrile (75 ml) contained in a glass-lined reactor similar to Example I is added, under nitrogen, 1.25 mmole (0.58 gm) of rhodium tris(acetylacetonate) and 4.2 gm of potassium iodide. The reactor is sealed, flushed with CO, and 10 gm of ammonia (587 mmole) is pressured in from a side ampule. The pressure is adjusted with CO to 20 atm while the agitated mixture is heated to 1200C. The pressure is further adjusted to 100 atm with CO and the mixture held at temperature for 8 hours. At this time the carbonylation is terminated by rapid cooling and venting the reactor. A small portion (0.1 ml) of crude liquid product is set aside for analysis, the remainder is fractionally distilled under reduced pressure (1--10 mm Hg) to recover the solvent and y-butyrolactam product.

Following the fractional distillation of the crude product, the residual liquid is recharged to the pressure reactor with fresh acetonitrile solvent (75 ml), allyl chloride (125 mmole) and ammonia (10 gm, 587 mmole). Carbonylation is again carried out as described supra.

Part B (for Comparison) The synthesis of Part A is repeated but substituting cobalt stearate for rhodium tris(acetylacetonate) on a mmole-per-mmole basis. No y-butyrolactam is detected by glc in the crude product solution.

Part C (for Comparison) The synthesis of Part A is repeated but substituting cobalt octacarbonyl for rhodium tris(acetylacetonate) on a mmole-per-mmole basis. No y-butyrolactam is detected.

EXAMPLE 15 Synthesis of N-Methyl-y-Butyrolactam from Allyl Iodide Using the procedure and equipment of Example 13, allyl iodide (125 mmole) and acetonitrile (75 ml) and rhodium tris(acetylacetonate) (1.25 mmole) are charged to the reactor, flushed with CO and 8 gm of methylamine injected from the side ampule. The pressure is raised with CO to 50 atm while the agitated mixture is heated to 120"C. after 8 hrs the carbonylation is terminated by rapid cooling, and venting the reactor. Analysis of the crude liquid product by glc shows the presence of N-methyl-y-butyrolactam.

As the numerous examples and preceding discussion have documented, the novel rhodium carbonylation catalysts of this invention are a significant improvement over the disclosed catalysts of the prior art, particularly regarding the yield of y-lactams and their homologues, the relatively mild conditions of carbonylation employed, and the proven activity of the used rhodium catalyst samples upon recycle.

A further advantage of the instant invention is that in some respects the process offers flexibility, that is, numerous modifications and changes can be made in the choice of catalyst and allylic substrate without departing from the inventive concept. The metes and bounds can best be determined by reading the claims which follow in light of the preceding specification.

Claims (12)

WHAT WE CLAIM IS:

1. A process for preparing a y-lactam by reacting carbon monoxide at an elevated pressure and a temperature of at least 200C with (i) an allylic amine or (ii) a mixture of an allylic halide, selected from allyl chlorides, bromides and iodides, with at least a stoichiometric amount of amine coreactant selected from ammonia and primary amines containing 1 to 12 carbon atoms, wherein the reaction is carried out in the presence of a rhodium catalyst selected from Chlorobis(ethylene)rhodium(I) dimer Chlorotris(triphenylphosphine)rhodium(I) Chorocarbonylbis(triphenylphosphine)rhodium(I) Rhodium tris(acetylacetonate) Rhodium chloride plus triphenylphosphine Rhodium chloride, and said rhodium catalyst bonded to a styrene/divinylbenzene polymer with appended nitrogen or phosphorus donor groups, but excluding the use of rhodium chloride by itself in the reaction of an allylic halide with an amine co-reactant.

2. A process as claimed in claim 1 wherein the temperature is between 20 and 250"C.

3. A process as claimed in claim 1 or 2 wherein the allylic halide is an allylic chloride or bromide, and reaction with carbon monoxide is carried out in the presence of an alkali or alkaline earth metal iodide promoter.

4. A process as claimed in claim 3 wherein the alkali-metal iodide promoter is lithium iodide, sodium iodide or potassium iodide.

5. A process as claimed in any preceding claim wherein the primary amine coreactant is methylamine, ethylamine or 2-ethylhexylamine.

6. A process as claimed in any preceding claim wherein the allylic halide is allyl chloride, 2-methylallyl chloride, crotyl chloride, allyl bromide, or allyl iodide.

7. A process as claimed in claim 1 or 2 wherein the allylic amine is allylamine, 2-methylallylamine or crotylamine.

8. A process as claimed in any preceding claim wherein the rhodium catalyst is bonded to a styrene/divinylbenzene polymer with appended diphenylphosphine donor groups.

9. A process as claimed in any preceding claim wherein lactam synthesis is carried out in the presence of an inert solvent.

10. A process as claimed in claim 9 wherein the inert solvent is an aromatic hydrocarbon, aliphatic hydrocarbon or aliphatic nitrile.

11. A process as claimed in claim 1 and substantially as hereinbefore described with reference to any of the Examples.

12. y-Lactams when prepared by a process as claimed in any of the preceding claims.