CA1056826A - Preparation of lactams and related intermediates and derivatives thereof - Google Patents

Abstract

ABSTRACT OF THE INVENTION
Lactams alone or in combination with terephthalic acid are prepared in a sequence of steps from the carbonyl halide reaction product of a cycloparaffin and phosgene and ultimately, where desired, carbon monoxide and chlorine, by acylation of benzene or an alkyl-substituted benzene with the carbonyl chloride derivative of the cycloparaffin;
and reduction and nitrosation of the resulting ketone; or, nitrosation alone, in the event the benzene nucleus is alkyl-substituted, to yield the desired lactam and aromatic acid which latter compound may be oxidized to the desired phthalic acid.

I

Description

BACKGROUND OF THE INVENTION:

This invention relates to processes for preparing lac~ams and, where desired, terephthalic acid.
The preparation of the acid halides of cycloparaf~ins by photochloroformylation of the cycloparaffins using phosgene has been known heretofore. Similarly, a number of methods of preparing caprolactam particularly have been disclosed, most conventional of which is that commonly employed commercially and involving the sulfuric lV acid-induced Beckmann rearrangement of cyclohexanone oxime. A discussion of various methods well known to those skilled in the art appears in an article by M.:~
Taverna and M. Chlti, Hydrocarbon Processes, pages 137-145 (November 1970). It has been necessary, however, to prepare cyclohexanone oxime intermediates, for example, by treatment of nitrocyclohexane or it:s salt with hydroxylamine, sulfuric acid, sodium nitrite or b~ treatment of cyclo-hexanonebisulfite com~lexes with niitrous acid or the like in a series of multistep processes which are either

2~ inefficient, relatively, in the use of the in~ermediates involved, begin with relatively expensive starting materials such as phenol, or the formation of undue amounts ~ ;~
of by~product, such as ammonium sulfate, for which there i9 a decreasing market due to a trend toward displacement . .
thereof with higher nitrogen content fertilizers. ~;
I~ has also been suggested, illustratively, that ~-caprolactam be prepared from cyclohexanecarboxylic acid and indeed, i~ is understood, that this method has also been used commercially. In addition, it has been proposed .
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that caprolactam be prepared by nitrosation of a yhenyl, or alkyl-su.bstituted phenyl, cyclohexyl ketone to yield the caprolactam and benzoic acid or alkyl-substituted benzoic acid.
I~actams are used in the production of poly-amides for the manufacture of fibers, films, fabrics, coating compositions and the like. Caprolactam or, more precisely, epsilon caprolactam, or 2-oxohexamethylenimine, is particularly useful when polymerized by a variety of con-ventional methods to provide the polyamide resin, nylon-6, one of the principal textile fibers in use today, or is polymerized with well-known diamines and dicarboxylic acids to form other polyamide resins also useful as fibers, fil-aments, bristles, extrusion and molded products, and the lS like.
If lactams and, particularly, caprolactam could :.
be derived from ketones in which both of the cyclic moieties attached thereto were used to form a lactam or if the cycloalkyl moiety were useful in making caprolactam and, illustratively, the other cyclic moiety useful in making terephthalic acid, which has an established utility in forming polyesters with glycols for use in films, sheets . :
and fibersj and if the ketones in turn were derived ultimately from phosgene, or carbon monoxide and chlorine, together with ryclohèxane or homologous cycloaliphatic compounds, a significant reduction in cost, more efficient - use o petroleum derivatives, and consequently, a sig-nLficant advance in the state of the art would be achLeved.

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-3-SUMMARY OF THE INVENTION:

I~ is, therefore, a general object of ~he invention to provide a novel, ef~icacious and inexpensive process for producing lactams, and particularly, epsilon-caprolactam It is a further objective of the invention to provide a method for producing lactams from inexpensive ~ -starting materials which provide the desired intermediates and final product in significantly high yields.
It is a still further object of this invention to provide a method which is sufficiently flexible to per-mit production o~ the desired lactams and other products, such as terephthalic acid, ultimately from the same initial materials and by varying the process to only a limited degree.
It is an additional object of the invention to produce minimal reactor effluen~; to be able to utilize any effluent resulting in produc~ion of further caprolactam or other desired products; and, in any event, to avoid pro-duction of difficultly marketable by-products.
These and other objects and ad~antages of this invention will becoMe evident ~rom the ollowing des-cription.
- Accordingly, it has now been discovered that lactams containing rom 5 to 8 carbon atoms (5 to 7 carbon atoms in the ring structure), and most desirably epsilon-caprolactam, and if desired terephthalic acid, can be prcpared from the corrèsponding saturated cycloaliphatic hydrocarbons containing 5 to 7, and preferably 6, carbon .

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:;, atoms in the ring nucleus~ and phos~ene, or carbon monoxide and chlorine, in addition to benzene~ or an alkyl-substituted benzene, in an economically feasible and efficient manner, using a minimum of inheren~ly flexible process steps9 while avoiding production of difficultly marketable by-products.
In one aspec~, there~ore, the invention provides in the process o~
producing a lactam the steps that comprise:
~1) acylating an aryl compound selected from benzene or toluene with a cycloalkyl carbonyl chloride, wherein said cycloalkyl group contains from 5 to 7 carbon atomS, to form the corresponding cycloalkyl carbonyl ketone;
(2) reacting said ketone (i) wherein said aryl moiety is derived from toluene, by nitrosa-tion to form from said ketone the corresponding lactam of the cycloalkyl moiety of said ketone and para-tolyl-carboxylic acid; and o~idizing the lat-ter to form terephthalic acid; or (ii) wherein the aryl moiety is derived from toluene or benzene, by sequentially hydrogenating the carbon-to-carbon double bonds of said aryl moiety and nitrosating the resulting dicycloalkyl ketone to form substantially from each reacted mol thereof, two mols of the corresponding lactam.
In another aspect the invention provides a process for the produc-tion of lactams that comprises the steps o~
(1) subjecting a member selected from (a) a mixture of chlorine and carbon monoxide or (b) phosgene, to ultra-violet irradiation in a solu-tion o~ a cycloalkane containing from 5 to 7 carbon atoms to form the corres-ponding cycloalkyl carbonyl chloride therefrom;
(2) acylating an aryl compound selected from benzene and toluene with said cycloalkyl carbonyl chloride to form the corresponding cycloalkyl aryl ketone; ~ -~3) reacting said ketone ti) wherein said aryl moiety is derived from toluene, by ni~rosa-i~'~: -': ' ~ ~ 4 ~ ~ ~

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, i .. , , .. , . , ,, : . , , -tion, to form from said ketone the corresponding lactam of the cycloalkyl moiety of said Icetone and para-tolyl-carboxylic acid; and oxidizing the lat- -ter to form terephthalic acid; or (ii) wherein the aryl moiety is derived from toluene or benzene, by sequentially hydrogenating the carbon-to-carbon double bonds of said aryl moiety and nitrosating the resul~ing dicycloalkyl ke~one to form substan-tially from each reacted mol thçreof, two mols of the corresponding lac~am.
DES~RIPTION OF THE PREFERRED EMBODIMENTS

The process of this invention is effected by the photoexcitation and decomposition o~ phosgene, or carbon monoxide and chlorine, which is be-lieved to form phosgene as an intermediate, in a solution including a cyclo-paraffin containing from 5 to 7 carbon atoms, that is cyclopentane, cyclohep-tane, and most desirably, cyclohexane, to form the corresponding alicyclic carbonyl chloride.
The formation of the alicyclic carbonyl chloride is accomplished within a range preferably of 15C to 40C and preferably at about 25C. The phosgene is irradiated using ultra-violet light from an at least 100-wat~
source, and up to 10,000 watts or more~ An ultra-violet source of 100 watts to 500 watts, desirably a mercury or tungsten lamp, is effectively employed with continuous sti~ring of the reaction mixture, where a limited amount of product is produced. Up to 10,000 watts and more is considered efficacious in commercial production of these alicyclic carbonyl chlorides. A continu-ous process, as well as a batch process, may be utilized. In the continuous flow me~hod, phosgene is introduced through a fritted disc at the bottom of a water-jacketed reaction vessel, into which phosgene and alicyclic compound are continuously '' '' ' , :, " ,' - 4a ~
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passed and removed after conversion t~ the c~rresponding alicyclic carbonyl chloride. The residence time in the reaction vessel is approximately 3 hours to 24 hours though shorter, or longer, periods are feasible and will depend on a variety of reaction conditions and the volume producPd and rate of reaction sought. The yields of alicyclic carbonyl chloride appear to be substantially quantitative. Hydrochloric acid and carbon monoxide are evolved in the course o the reaction and may be collected, if desired, by conventional means. Conventional labora-~
- tory scale irradiation equipment such as a Hanovia (608A-36) mercury lamp or 3000 A la~ps in a Rayonet reactor may be employed in the photolytic procedures of this invention.
The levels o conversion o the foregoing cycloparaffins to the desired corresponding alicyclic carbonyl chlorides by this irradiation step, where phosgene is employed, is as high as 60 per~ent in the case of cycloheptane and 75 percent to 90 percent, and indeed 95 percent, in those -instances where cyclohexane and cyclopentane are employed as reactant. Phosgene and the cycloparaffins, such as the preferred cyclohexane, are, as indicated generally herein-above, inexpensive star~ing materials, and the yields of desired product secured by the photolytic process of the .
invention are significantly great. Cheaper materials i ~5 yielding lower concentrations of the desired carbonyl chloride may also be utilized by substituting carbon monoxide and chlorine for phosgene in the equipment and process described for photochloroormylation of cyclo-para~fins hereinabove. Where so employed, carbon monoxide ' ~ ' -6~

and chlorine are bubbled through a fritted disc at the bottom of a reactor containing alicyclic component and an inert organic cosolvent, such as, preferably, diethyl ether, acetone, methyl ethyl ketone or other oxygenated hydrocarbon solvent. The cosolvent is employed in a volume up to about twice that of the cycloparaffin presen~.
As noted above, it is believed, although it is not in-tended that this invention should rely on thc correctness of this belief, that phosgene is formed in the course of this photoactivation. The residence time of the reactants in the reaction vessel subject to ultra-violet irradiation is not narrowly critical and may be, for exa~p:Le, about 3 hours or less to 24 hours or more. The yields secured are less than where phosgene, itse:Lf, is photoactivated.
The alicyclic carbonyl chloride, that is cyclo-hexanecarbonyl chloride, cycloheptanecarb~nyl chloride, or ; cyclopentanecarbonyl chloride when so prepared, is, in ; accordance with this invention, then contacted with benzene or toluene in the presence o~ a Fr:iedel-Crafts catalyst, ~0 and most desirably, aluminum chloride, to yield the corresponding alicyclic aroma~ic ketone. Illustratively, where cy lohexanecarbonyl chloride and benzene are`the reactants, the reaction product secured is cyclohexyl phenyl ketone. Similarly~ where cyclopentylcarhonyl chloride or cycloheptylcarbonyl chloride is the reactant, the reaction product resulting from this acylation pro-cedure i cyclopen~yl phenyl ketone or cycloheptyl phenyl ketone, respectively. Where toluene is substituted for benzene, ~he products recovered are substan~ially cyclohexyl .
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para-tolyl ketone, cyclopentyl para-tolyl ke~one, and cycloheptyl para-tolyl ke~one, respectively.
This acylation procedure whereby the alicyclic carbonyl moiety is introduced into the aromatic nucleus is well known and is that described in detail, by way of illustration, by G. Olah, Friedel-Crafts and Related _ Reactions, vol. 1, page 93, Interscience Publishers, 1963.
The amount o catalyst employed is normally in a ratio of about one gram molecular weight, and most desirably slightly in excess thereof, of catalyst to each gram molecular weigh~
of alicyclic carbonyl chloride Obviously, greater or less-er concentrations of catalyst may also be optionally em-ployed although less desirably so in terms of eficiency.
Although anhydrous aluminum chlori.de is preerred, any con-ventional Friedel-Crafts catalysts and particularly the Lewis acid metallic halidesl such~ for example, as boron trifluoride, ferric chloride~ zinc: chloride, double salt aluminum chloride ? boron trichlori.de or boron tribromide ,~
may be employed. The function of the catalyst is to generate the ac~ive substituting agent, the acyl cation. The reaction is normally but optionally carried out in an inert organic solvent such as carbon disulfide or nitrobenzene. These latter solvents are employed in amounts of about 25% to 30%
by weight of the component alicyclic carbonyl chloride present in the reaction mixture. Acylation is usually effected in the presence of a greater quantity o Friedel- ;
Crafts catalyst than that employed in standard alkylation reactions. The acylation reaction is easily controlled to -give monosubstitution, for once an acyl group is attached ~ -to the benzene ring, lt is not normally feasible to ~-. .
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. . . : , . . -ln~roduce a second acyl group into the same aromatic nucleus. If desired to accelerate the reaction, fuming sulfuric acid in small amounts, that is, about 5 to 20 mol percent based on the Friedel-Crafts catalyst employed may be employed in combination with, illustratively, ~he aluminum chloride catalyst, The benzene or toluene is reacted in essentially equimolar proportions with the cyclohexanecarbonyl chloride, cyclopentane carbonyl chloride or cycloheptane carbonyl chloride. Where toluene is treated, acyla~ion occurs in the aromatic ring nucleus para to the attachment of the methyl su~stituent, as indicated above.
The ketone so secured, in accordance with a preferred embodiment of the invention, is subjected to selective reduction; the carbon-to-carbon double bonds of the aromatic nucleus being saturat:ed, using a conventional ; Raney nickel, platinum, palladium or other hydrogenation catalyst, A preferred method of effec~ing the desired hydrogenation involves contacting the ketone, at an elevated tem~erature~ e.g. 150C to 1~0Ct in a hydrogen atmosphere of about 10 to 17 atmospheres with palladium reduced from its oxide, and supported on active carbon, in a serieo of stirred reactors, and in liquid phase for a period sufficient to hydrogenate the carbon-to-carbon double bonds present.
- This step is readily effected since hydrogenation of ketone carbonyl groups is much slower than that of carbon-to carbon double bonds and is well known in ~he relevant art.
Catalyst is recovered as a slurry by centrifuging the re-action liquid stream; and resubmission of the catalyst to , : . ' ;,. :,' , ' "; ' ~ .' .

_9_ the reactor. The product ketone is condensed from the vapor phase before submission to the next step of this reaction sequence. The reduced compounds are dicyclohexyl ketone, cyclopentyl cyclohexyl ketonel or cycloheptyl cyclohexyl ketone resulting from reaction of the corres-ponding alicyclic carbonyl chloride recited above with -benzene and wherein a cyclohexyl group i~ secured by the foregoing hydrogenation of the benzene moiety; or cyclohexyl-4 methylcyclohexyl ketone, cyclopentyl-4-methylcyclohexyl ketone, and cycloheptyl-4-methylcyclo-hexyl ketone, where toluene has been substituted for benzene. ` ;
A ketone such as the foregoing is then, in con-tinuing the practice of the preferred embodiment, reacted, in a manner similar to that described in Italian patent 608,873, issued September 21, 1960. In accordance with this process, a mole of the complet:ely hydrogenated di(ali-cyclic) ketone, such as describet hereinabove, is subjected to nitrosation to yield one mole of epsilon-caprolactam and one le of alicycli~ carboxylic acid, for example, cyclohexylcarboxylic acid, where this moiety is derived from benzene, or 4-methylcyclohexyl-1-carboxylic acid, where toluene has replaced the oregoing benzene. The carboxylic acid is not a by product as described in Italian patent 604,795, issued May 14, 1960, but is labile to the reaction conditions in w~`ich the caprolactam is formed, and forms, upon reaction wi~h the nitrosyl sulfuric acid, a second mole of epsilon caprolactam where derived from henzene, or methyl caprolactam where derived from toluene~
' In addition, nitrosyl sulfuric acid, nitrosyl-chloride, N202, and sodium nitrite in sulfuric acid may also be employed as nitrosating agents.
In a second e~bodiment, where toluene is acylated~
one mole of the alicyclic aryl ketone product is, rather than being hydrogenated, reacted, as in the foregoing SNIA process ~see Italian patent 604,795, issued May 14, 1960), by nitrosation to yield one mole of epsilon-capro-lactam and para-methyl benzoic acid (para-toluic acid); the latter compound being readily converted to terephthalic acid upon mild oxidation using, illustratively, a standard nitric acid procedure, such as described in British pat~nt 655,074 (July 11, 1951) and U.S. patent 2,636,899, or air oxidation techniques.
Where 2 moles of caprolactam are being formed, nîtrosation is effected using desirably two moles, or pre-ferably slightly in excess of two moles, e.g.) up to about 2.5 moles or more, of mono-nitrogen containing nitrosating agen~ such, most desirably, as nitrosyl sulfuric acid,per mole of ketone. Where one mole of caprolactam and one mole of para-~oluic acid are ~o be prepared substantially equi-molar proportions, and most desirably a slight excess, usually not over 1.5 moles~ but optionally up to 2.5 moles or more, of monatomic nitrogen-containing reactant, prefer-ably nitrosyl sulfuric acid, is utilized per mole of reactantketone. Where nitrosyl sulfuric acid is employed, concentrated ; sulfuric acid containing an excess of S03, produced by mix-ing one part by weight of concentrated sulfuric acid and slightly in excess of one part by weigh~ of ole~m, is in- -corporated as solvent t Where diatomic nitrogen-containing compounds are used, e.g., N202, suitable adjustment of ~he foregoing mole ratios is made.
In addition, the caprolactam can be se~arated from the sulfuric acid of the reaction mixture by extraction with an alkylphenol solvent using known techniques. Th~
sulfuric acid remaining is thermally cracked according to this practice destroying the impurities present while forming sulfur dioxide for recycle.
The time of reaction is not narrowly critical in any of the foregoing steps embodying the process of this invention, and in any event, may be adjusted so as to complete the reaction.
The present invention is further illustrated by the following examples:
Example I
This example illustrates the preparation of cyclo-hexylcarbonyl chloride from carbon monoxide and chlorine.
Carbon monoxide and chlorine were bubbled through ~ a fri~tad disc at the bottom of a reactor containing by 20 volume L part cyclohexane to 2 parts of diethyl ether The gases were admitted continuously;at a rate of 80 cubic centimeters per minute. The resulting solution was irra-diated with ultra-viole~ light emit~ed from a 100-watt medium pressureJ Hanovia (60B-A-36) mercury lamp through a quartz filter or a period of 5 hours. The crude reaction mixture was subsequently distilled and cyclohexanecarbonyl chloride recovered therefrom.
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This example illustrates the preparation of cyclohexyl carbonyl chloride from phosgene in a batch process.

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Phosgene (13.6 grams) is condensed and passed directly into a reactor containing 140 milliliters (116.4 grams) of cyclohexane and a magn~tic stirrer and the solution is then irradiated for 3.5 hours using a 100-watt, medium pressure, Hanovia (608A-36) mercury lamp with a quartz probe. The photolysis of the phosgene is conducted with stirrin~ and the reaction contents are maintained at about 25C by a water jacket. The reaction product mixture becomes darker with increased photochemical treatment over an increased period o time. The product mixture is se-quentially stripped of unreacted phosgene and cyclohexane.
The residue is then vacuum distilled for analysis; and the monoacid chloride, cyclohexanecarbonyl chloride, is re-covered therefro~ in a yield of at least 35 percent. An additional ten percent of polysubstituted cyclohexane acid chloride was also formed by the re,action.
Ex mple III
.
This example illustrates the preparation of cyclohexane carbonyl chloride from phosgene in a contin-20 ~ uous process, Phosgene is bubbled through a fritted disc at the bo~tom of a standard reactor vessel suitable for photochemical reactions filled with cyclohexane and the resulting solu~ion irradiated in the manner of Example I
to yield cyclohexanecarbon~l chloride.
Example IV
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This example urther illustrates the preparation of cyclohexanecarbonyl chloride according to the practice o the invention in which the ratio o reactants i5 varied.
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The procedure of Example II is repeated in three runs in which the reactants, the period of time during which irradiation occurs and the yields secured are as recited in Table I: -Table I

Run 1 2 3 :

cyclohexane ~moles) 1.3 1.2 1.2 phosgene 0.13 0.52 0.16 hours 3.75 11.75 7.0 10 percentage of cyclohexane carbonyl chloride 40 35 25 percent of other reaction products 12 7.4 26.2 E ample V ~;

This example ~urther illustrates ~he preparation o a plurality of cycloalkane carbonyl chlorides according to ~he prac~ice of the invention in which further variation in the ratio of reactants is effected, The procedure of Example II is repeated in four runs in which the reactants~ the reaction period and yields are as described in Table II.

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Table II
Run 1 2 3 Hydro- cyclo- cyclo- cyclo- cyclo-carbon hexane heptane pentane pen~ane Amount of hydrocarbon, grams: 230 117 245 104 moles: 2.7 1.2 2.06 105 Phosgene, grams: 15.6 13.7 11,4 18.0 moles: .15 .12 .11 .18 Hours: 5.5 9.5 4.5 5 Phosgene, con~ersion (%)25-30 40 45 20-25 alicyclic carbonyl chloride, yield 90-95 60 90 90 Example VI
This example illustrates the acylation o toluene wi~h cyclohexanecarbonyl chloride l:o orm ~yclohexyl para-tolyl ketone.
The reaction is carried out in a 250 milliliter (ml) flask, provided with a magnetic stirrer and drying tu~e. Introduced into the flask initially were 8.0 grams ; (~.055 mole) o cyclohexyl carbonyl chloride and 150 ml of toIuene (previously distilled over lithium aluminum hydride) and mixed thoroughly prior to addition slowly to the solu-. ~ .
tion o 8.6 grams (0.065 mole~ of anhydrous aluminum .
; 30 chloride. The solution turned yellow with the evolu~ion ~ -of gas.
The flask was closed off using the drying tube .: ~o vent the gas. The drying tube was then replacad by a ';' ~ ~:
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reflux condenser and the drying tube was then inserted above the condenser. Stirring of the reaction mixture was initiated with generation of heat. The reaction flask was then flushed with ni~rogen and heat applied to the reaction solution. A slow purge of nitrogen was per-mitted to pass through the flask and the reaction vessel was so maintained with heating for a period of about twenty hours. Fifty milliliters of ice water was added to the flask when the heat was removed resulting in the forma-tion of layers. The foregoing layers were separated in a separatory funnel and the aqueous layer thereafter washed once with anhydrous ether. Anhydrous magnesium sulfate was added to the organic layer. After sitting for 2.5 hours the magnesium sulfate was filtered off. The solution remaining was then placed on a rotary vacuum to effect removal of toluene and ether. The remaining liquid was sub~ected to vacuum distillation. The tendency of the recovered product to solidify was overeome after successive addition to and evaporation- from the solid of petroleum etherl and thereaf~er methanol and water with sequential coolin& to room temperature and below.
Crystalline cyclohexyl para-tolyl ketone having `
a melting point of 64.5 Centigrade (C) to 67C was re- ~ -covered in a total amount by weight of 6.80 grams.
This example illustrates the acylation of benzene with cyclohexanecarbonyl chloride ~o form cyclohexyl phenyl ketone. ~
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The reaction is carried out in a 250 ml. three-neck flask to which benzene (150 ml) stored over a molec-ular sieve and distilled from calcium hydride was intro-duced directly.
A drying tube was the only vent means supplied to the flask, The flask was then closed and placed in a dry box. Cyclohexyl carbonyl chloride (about 5 to 5.5 grams) was next added to ~he benzene follcwed by 9,0 grams of an-hydrous aluminum chloride causing the solution to turn yellow with evolution of gas. The flask was closed off with ~he dry-ing tube and under a hood ~ reflux condenser was attached with the drying tube af~ixed to the top of the condenser and a bubbler attached to the drying tube. The system was flushed wi~h nitrogen and,the reaction mixture stirred causing the re-action to give off a little heat. The ga~s evolved from the reaction mixture was acidic, Vigorous bubbling of the reaction was observed for a periocl o~ about five minwtes.
A slow purge of nitrogen was then undertaken. ~fter about three to four hours heat was applied to reflux and after ,~
2.5 additiona~ hours the reaction mixture was permitted to cool ~o room temperature and 50 ml of ice water added.
Some heating was noted, The solution was separated into an aqueous and organic layer and placed in a separatory funnel f~r recovery individually of the two layers. The -aqueous, layer was wa~hed once with e~her. Anhydrous ammonium sul~ate was added to the organic layer which was then permitted to sit overnight. The organic layer was ;, . filtered ~nd washed with ether, The solution was then' placed on a rotary vacuum to remove the excess or un- , reacted benzene and ether, The liquid remaining was then subjected to vacuum distillation. The residue remaining after distillation consti~utes ~he desired produc~, cyclo-hexyl phenyl ketone, in an amount by weight of 7.5 grams.
Exam~le VIII
This example illustrates the selective reduction of cyclohexyl phenyl ketone.
Cyclohexyl phenyl ketone is passed through a closed vessel in which a hydrogen atmosphere of about 10 to 17 atmospheres obtains. The vessel is heated to a temperature of from 150 degrees centigrade (C) to 190C.
Palladium, reduced from its oxide, is disposed on a support of active charcoal within the vessel and the ketone brought into contact therewith by circulation of the atmosphere therein for a period sufficient to effect hydrogenation of the carbon-to-car~on double bonds of the benzene moiety to yield dicyclohexyl ketone.
xample IX
This example illustrates the selective reduction of cyclohexyl-para-tolyl ketone.
,20 The procedure of Example VIII is repeated sub-stituting cyclohexyl-para-tolyl ketone for cyclohexyl --. ., -phenyl ketone. The product recovered is cyclohexyl-4-methyl-cyclohexyl ketone.
Exam~ X
This example illustrates the nitrosatlon o~
dicyclohexyl ketone to produce epsilon caprolactam.
Into a 100 cubic centimeter (cc) round-bottom flask is introduced 18.6 grams ~0.1 mol) of dicyclohexyl ketone dissolved in 15 grams of concentrated sulfuric acid.
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The ketone îs treated with a mixture of 21.4 grams (0.192 mol) of purified ni~rosylsulfuric acid, 26 grams of sul-furic acid and 25 grams of oleum (60 percent) ror a molar ratio of nitrosylsulfuric acid to ketone of 2:1.04 res-pectively, The final temperature of the reac~ion mixture after the introduction of the nitrosa~ing mixture is 65~C.
The reaction mixture is poured onto ice, where-upon substantial quantities of unidentified resinous product separate out. The mixture is then shaken with ether and without separating out the layers, which tend to form at ~his point, the mixture is filtered to remove undissolved resin. The recov~red liquors are thereafter ~-neutralized with approximately 40 percent caustic soda, sequentially, a 10 percent sodium carbonate solutîon which I5 is ~hen extracted with chloroform and evaporated to yield 8.09 grams of impure, crude caprolactam a~d 1.7 grams of ~-unreacted ketone.
Ex ~ X~

This example illustrates the nitrosation of dicyclohexyl ketone to produce epsilon-caprolactam.
Employing the procedure of Example X, one mole of dicyclohexyl ketone is reacted with about 2.5 moles of nitrous acid in 89 percent sulfuric acid and the mixture heated at about 60C for three and one-half hburs. There is formed substantially two mols of epsilon-caprolac~am.
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.
This example illustrates the nitrosation of cyclohexyl-4-methylcyclohexyl ketone.

The process o:E Example X is repea~ed substituting cyclohexyl-4-methylcyclohe~yl ketone for the dicyclohexyl ketone therein, The product recovered is substantially one mol of caprolactam and one mol of gamma-methyl caprolactam.
Example XIII
This example illustrates the preparation of epsilon-caprolactam and para-toluic acid, About fîfteen grams of cyclohexyl para-tolyl ketone having a melting point of 66C to 67C are added slowly during the course of one hour to approximately 42.6 grams of oleum having an S03 content of 23 percent, wi~h agitation and with cooling, in such a manner that the tem-perature does not exceed 30C to 35C. Thereupon7 3,7 grams of sodium nitrite are added to the mixture, at all times with constant agitation, and gradually over the course of another hour, the temperature being maintained at :
38C to 40C, When everything has passed into solution, the solution is poured onto ice. The resulting mixture is ex~racted three time~ with about S0 cc of ether. Upon combining the extracts separated from the water, there is obtained an e~her raction and, separately, an aqueous solution, By extractin~ the ethereal solution with 75 cc of 10% sodium carbonate solution and acidifying the aqueous solution contai.ning the carbonate with hydrochloric acid, . .
there are obtained about 5,65 grams of ~rude para-toluic ; acid w~ic~, when recrystallized and dried, yields approx-imately 5,1 grams of pure para-toluic acid. The remaining ether ls dried and evaporated. A residue of about 7,5 grams of material occurs which, after elimination of oily - ' '' ' "

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impurities which have formed, yields about 7,5 grams of unreacted cyclohexyl para-tolyl ketone having a melting point of 66C to 67C.
The ori~inal aqueous solution~ obtained by separation of the ether extract men~ioned above, is neutralized by ~he addition of 58 cc of a 40% sodium hydroxide solution and thereupon by successive addition of a few drops of a 10% solution of sodium carbonate.
The resulting solution is then extracted six times with about 20 cc of chloroform each time. From the chloroform extracts, combined and dri~d, ther~ are obtained, after elimination of the solvent, about 4.7 grams of caprolactam of a melting point of 65-69C~
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This example illustrates the preparation of epsilon-caprolactam and terephthali.c acid.
. Employing the procedure of Example XIII, a mixture of cyclohexyl para-tolyl ketone (2.0 grams) having a melting point of 66C to 6-7~ and sodium nitrite (1.4 ~.
2a grams). in 89 percent sulfuric acid is heated at 60C for 3.5 hours to yield epsilon-caprolactam and para-toluic acid~ The latter acid is recovered from the reaction product mixture and thereafter oxidized using nitric acid ~100 percent) in a weight ratio to reactant para-~oluic acid of about 2.4 to 1 respectively. The yield of tereph-thalic acid based on reactant para toluic acid is about 85 .~: -percent, Much of the nitrlc acid is readily recovered for ~urther use, It will be evident that the terms and expressions .. ~.
which have been employed are used as terms o~ descriptio~ .

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and not of limitation, There is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof and it is recognized that various modifications are possible within the scope of the invention claroed, ., ~
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Claims

The embodiments of the invention in which an exclusive property of privilege is claimed are defined as follows:
1.
In the process of producing a lactam the steps that comprise:
(1) acylating an aryl compound selected from benzene or toluene with a cycloalkyl carbonyl chloride, wherein said cycloalkyl group contains from 5 to 7 carbon atoms, to form the corresponding cycloalkyl carbonyl ketone;
(2) reacting said ketone (i) wherein said aryl moiety is derived from toluene, by nitrosation to form from said ketone the corresponding lactam of the cycloalkyl moiety of said ketone and para-tolyl-carboxylic acid; and oxidizing the latter to form terephthalic acid; or (ii) wherein the aryl moiety is derived from toluene or benzene, by sequentially hydrogenating the carbon-to-carbon double bonds of said aryl moiety and nitrosating the resulting dicycloalkyl ketone to form substantially from each reacted mol thereof, two mols of the corresponding lactam, 2.
A process for the production of lactams that comprises the steps of (1) subjecting a member selected from (a) a mixture of chlorine and carbon monoxide or (b) phosgene, to ultra-violet irradiation in a solution of a cycloalkane containing from 5 to 7 carbon atoms to form the correspond-ing cycloalkyl carbonyl chloride therefrom;

(2) acylating an aryl compound selected from benzene and toluene with said cycloalkyl carbonyl chloride to form the corresponding cycloalkyl aryl ketone;
(3) reacting said ketone (i) wherein said aryl moiety is derived from toluene, by nitrosation to form from said ketone the corresponding lactam of the cycloalkyl moiety of said ketone and para-tolyl-carboxylic acid; and oxidizing the latter to form terephthalic acid; or (ii) wherein the aryl moiety is derived from toluene or benzene, by sequentially hydrogenating the carbon-to-carbon double bonds of said aryl moiety and nitrosating the resulting dicycloalkyl ketone to form sub-stantially from each reacted mol thereof, two mols of the corresponding lactam.
3.
The process of claim 1 wherein said cycloalkane is cyclohexane.
4.
The process of claim 1 wherein said cycloalkane is cyclopentane.
5.
The process of claim 1 wherein said cycloalkane is cycloheptane.
6.
The process of claim 1 wherein said acylation occurs in the presence of a Friedel-Crafts catalyst.
7.
The process of claim 6 wherein said Friedel-Crafts catalyst is aluminum chloride.

The process of claim 1 wherein said aryl com-pound is benzene.
9.
The process of claim 1 wherein said aryl com-ponent is toluene.
10.
The process that comprises subjecting the carbon-to-carbon double bonds of a cycloalkyl aryl ketone wherein said cycloalkyl radical contains from 5 to 7 carbon atoms in its ring structure and said aryl radical is a phenyl or tolyl moiety, to hydrogenation and sequentially nitrosating the resulting dicylo-alkyl ketone to form substantially two mols of lactam from each mol of reacted ketone.
11.
The process of claim 10 wherein the cycloalkyl moiety of said cycloalkyl aryl ketone is cyclohexane.
12.
The process of claim 10 wherein the cycloalkyl moiety of said cycloalkyl aryl ketone is cycloheptane.
13.
The process of claim 10 wherein the cycloalkyl moiety of said cycloalkyl aryl ketone is cyclopentane.
14.
The process of claim 10 wherein the aryl moiety of said cycloalkyl aryl ketone is phenyl.
15.
The process of claim 10 wherein the aryl moiety of said cycloalkyl aryl ketone is tolyl.

16.
The process of claim 10 wherein said cycloalkyl aryl ketone is cyclohexyl phenyl ketone.
17.
The process of claim 10 wherein said cycloalkyl aryl ketone is cyclohexyl para-tolyl ketone.