Patented Oct. 31, 1933 1,933,215 UNITED STATES PATENT‘ OFFICE

PREPARATION OF KEToNEs ‘ ' Clyde 0. Henke, South Milwaukee, Wis., assignor, by mesnc assignments, to E. I. du Pont de, Nemours & Company, a corporation of Del aware No Drawing. Application December 1, 1930 1 Serial No. 499,412 14 Claims. (01. 260-134) This invention relates to a process for pro similar hydrocarbon has been used only as a. ducing ketones. ' ~ solvent for the alcohol. In other words, it was It is an object of this invention to provide a never appreciated in the art that" the benzene process to produce ketone's from secondary al— hydrocarbons could be made to act as oxidizing o‘ cohols in high yields and of exceptional purity. or dehydrogenationagents by becoming hydro 60' Another object of this invention is to pro genated themselves. _ ' _ ' duce ketones from secondary alcohols by treat Thus in U. S. Patent 9951,43’? to Aschan dated ing the latter in liquid phase with unsaturated June 6, 1911, hydrocarbons such as‘xylol, paraf cyclic hydrocarbons in the presence of a hydro fin and petroleum are used as solvents in the to genation catalyst and under temperature and preparation of camphor from a borneol. These 65: pressure conditions normally corresponding to hydrocarbons acted only as solvents in the

the optimum conditions for hydrogenating said process mentioned. ' ' ' unsaturated cyclic hydrocarbons. 'As a result, nowhere in the art has it been A speci?c object of this invention is to pro; pointed out that the reaction could be’ facilitat duce camphor from a borneol in thejpresence ed by providing conditions generally favorable of a hydrogenation catalyst and an unsaturated for hydrogenation such as'theoretical quantities cyclic hydrocarbon acting as a dehydrogenating of reacting agents, the presence of a hydrogena or oxidizing agent. ' _ ' 1 ~ tion catalyst, and use of elevated temperatures

Other and further important objects ‘of this and pressures. ' ‘ ‘ 20 invention will become apparent from the dis I have found that when the aromatic hydro closures in the following description and ap carbon is present in quantities not less than that pended claims. ' amount theoretically equivalent to theamount This invention more specifically deals with, of hydrogen split off from the secondary alcohol, for example, the following types of ketones: and the reaction carried out under pressure, the ' camphor, fenchone, cyclohexanone and acetone. yields of ketone are considerably increased.’ This The corresponding alcohols serving as start-_' e?ect was not to be foreseen on.~the‘ theory that ing materials for theabove named ketones are the aromatic hydrocarbon acts merely as, a

respectively borneol or iso-borneol, fenchyl al diluent. ' - ~ cohol, cyclohexanol and isopropyl alcohol. ,_ The following examples will serve to illustrate 30 I have found that secondary alcohols of the my invention in greater detail but it should be 85 type mentioned above can be readily converted understood that my invention is‘ notlimited to into the corresponding ketones by heating them the same and is susceptible to various modi?ca; in the liquid phase under pressure with an uni tions and variations as will be readily under-1 saturated cyclic hydrocarbon of the type that stood to those skilled‘ in the art. ' " 335 is readily hydrogenated such as, for example, benzene, naphthalene, ‘abietene, or dipentene. Example 90" The process is preferably carried out in the 1000 parts of borneol, 1000 parts of benzene and presence of a hydrogenation catalyst and under 40 parts of a hydrogenation catalyst, for instance temperature and pressure conditions corre nickel, are charged into an autoclave. The lat sponding to the normal hydrogenation condi ter is closed, the air removed therefrom by evacu 95 tions for the respective hydrocarbon. ation or byblowing hydrogen through the auto . Thus, I have found that if a borneol (borneol clave, and the mass is heated to 200° C.-and kept or iso-borneol) is heated to about 200° C. in an at this temperature and under its own pressure autoclave with a quantity of benzene, toluene or for 5 hours while stirring. The reaction mass is other unsaturated cyclic hydrocarbon, at least now cooled and ?ltered to removethe catalyst. 10k) equal to the amount theoretically necessary for The benzene and its hydrogenation products are absorbing all the hydrogen split off from'the now removedby distilling the reaction, mass until alcohol, and in the'presence of a hydrogenation the temperature rises to about 207° C., which cor catalyst such as nickel a reaction results yield responds to the boiling point of camphor. The ing camphor on the one hand‘ in a high state of residue in the still is substantially pure camphor 105 purity and yielding as a by-product hydrogenat and may be used as such. _If desired, however, ed benzene or toluene respectively. Although it it may be subjected to sublimation for the sake has been known to use benzene or a similar hy of further puri?cation. The fractions of benzene drocarbon as a solvent'or diluentin the oxida and hydrogenated benzene carry over with them tion of borneol to ‘camphor, the benzene or some of the camphor, which may be recovered 110 2 1,933,215 from the fractions in any suitable manner, for pressure for 5 hours. Upon fractionation as instance, by redistillation. The total yield of above, acetone is secured. camphor in this process after combining there In a similar manner, cyclohexanol and ben with the camphor recovered from the distillate, zene, cyclohexanol and naphthalene or cyclohex amounts to from 950 to about 958 parts by anol and dipentene may be heated together to 80 weight}. If the initialaborneolz was:pune,.therprod giwerespectively cyclohexanone and hydrogen not is ofexceptionally high purity having a melt ated" benzene, cycl'ohexanone and tetrahydro ing point of about 178° C. ~ ‘ naphthalene, or cyclohexanone and menthane, Instead of borneol in the above example, iso which may be separated from each other by frac 10 borneol may be used, with the same results. tionation as above. 85 Instead of nickel, nickel oxide‘ or‘ a: nickel ,o? benzene or naphthalene, toluene, carbonate-copper carbonate mixture may be abietene, or any other suitable unsaturated cyclic used. The catalytic mass'may' then» beilrstv re hydrocarbon-may be; used. The requisite of the duced with hydrogen unden pressure in the reac hydrocarbon i's-thatx it shall not be in the hydro 15 tion mixture at the reaction temperature, where genated‘ state; in, other words, it must contain 9O upon the procedure is continued as before. This double bonds capable of absorbing hydrogen. step, however, is not always. essentiai‘, for: the. , Another requisiteis that the unsaturated cyclic secondary alcohol itself will reduce part. of. the hydrocarbon be present in proportions at least catalyst, which in turn will promote the, dehydror theoretically equivalent to the quantity of hydro 20 genation of the alcohol and the further reduc gen split off from the alcohol assuming that all 95 tion 0t vthecatalystc until- all. of the latter is in of the, alcohol. will be converted into- ketone. reduced state whereupon, the hydrogenation Large excesses of unsaturated substance may- be at. the hydrocarbon- proceeds as before. The used, andv the yield is thereby generally increased. amounts of catalyst may be varied within. wide For best purposes, anunsaturated hydrocarbon should be selected which after-hydrogenation has 100 In my preferred method, I. use amount of a boiling, point. or boiling’ range: considerably catalyst equal to from. 2 tl0-.6‘%. by weight-of. the above or below the boilingpoint of the‘, ketone inltiai amount of alcohoL. However, considerable formed, thereby facilitating the separation of the variation»I inthis proportion may be. made. Thus, reaction products by fractionation, Furthermore, 1%! and 1.0%- are not extreme proportions. _ where the alcohol to bedehydrogenated has a high 105 It will be; understood of’. course that the reac boiling: point, the hydrocarbon selected should tion mass must be free from catalyzer poisons preferably be of a low boiling point to insure luck as sulfur compounds, For the‘: same reason, the formation of the requisite pressure’ without it will be found; advantageous to- use an unsatu recourse to excessive-temperatures. This pressure rated hydrocarbon which has beempre-puri?ed may vary considerably depending, on the sub 110 to-ridqit of catalyzer poisons in. accordance with stance being hydrogenated. 100. and 300 pounds per square inch are, convenient limits. How kiwwnmethods.The purity of; the.- resultant eamphoi'p depends. . ever, this latter selection of boiling points is not necessarily on the purity of the borneol_com.-_ absolutely essential, since the pressure in the pounds startedwith ‘ It the initial material; is vessel may be arti?cially built up by pumping 115 run, the product can. be- obtained substantially in- hydrogen, or an inert gas such as C02. The temperature in any speci?c case need not 100% pure.‘ _ ' 1 be: maintained at a precise- point, but may vary g ‘ Example 2 7 within substantial limits. Thus, while I have mo, parts of borneol, 650- parts of benzene and indicated;20.0° C. or 225° C. as the preferred tem 120 ‘I8 partsot catalyst are treated in the. same man perature in the examples, the same may vary from ner as in Example 1. .Theyield of: camphor is ‘175, to. 250? C. during the reaction without se substantially the same as in Example 1. riously affecting, the results. In the’ claims below; it should be. understood > I’ IV ‘7 Example 3' _ that the term “a borneol’fis meant to cover and 125 . mi-Taaméiave is. charged with 650. parts of include both borneol and isoborneol. bomeoL- lwpartsof. benzene and 39 parts. of Y I. ware that numerous. details of the process niakek, The rest of the procedure is substantially may be varied through a wide range without the same as in Example 1 and the yield is sub departing from the principles of this invention, stantially the same. and I, therefore, vdo not purpose. limiting the 13.0 patent granted hereon otherwise than necessi Example 4 tated by the prior art. 1000 parts of fenchyl. alcohol, 1M0 partsoi' I claim as my invention: > benzene and‘ 40 parts of a mixed nickel catalyst 1. The process of converting a secondary al cohol into the corresponding ketone which com 135 emrprlsinggnickel‘ and copper. carbonates are prises heating the secondary alcohol under pres charged into an autoclave. After reducing the sure in the liquid phase with an unsaturated cyclic catalyst'vwith hydrogen as explained above, the hydrocarbon in the presence of a hydrogenation mass is heated at 225°‘ ,C'. for 5 hours catalyst, 05 under pressure; The reaction mass is fraction 2. ‘The process of convertinga secondary alco 140 sted to remove'the benzene and its hydrogena hol into the corresponding ketone, which com tion ‘products and a high ‘yield ‘(about 97% of prises heating the secondary alcohol under pres theory) of substantially pure fenchone is secured. sure in the liquid phase with an unsaturated Example 5 cyclic hydrocarbon and a hydrogenation catalyst, 7.0 the» unsaturated cyclic hydrocarbon being pres 145 ‘An autoclave is charged. with 400 parts of'iso ent, in a proportion not less than that theoret propyl alcohol, 160!) parts of naphthalene and 40 ically required for. complete reaction with all parts of a mixed nickel catalyst as used in Ex of the hydrogen eliminated from the alcohol. ample 4. After reducing the'catalyst', the reac 3. The process of converting a terpene second n. 01 tion mass is heated at 225°‘ 0. under its own ary alcohol into the corresponding ketone, which ' 1,933,215 3 comprises heating the alcohol under pressure in 10. The process of producing camphor in high the liquid phase with an aromatic hydrocarbon yields, which comprises heating with a hydro capable of being hydrogenated, in the presence of genation catalyst, a borneol in the liquid phase a hydrogenation catalyst. in a closed vessel in the presence of an unsatu 4. The process of converting a terpene sec rated cyclic hydrocarbon which after hydro ondary alcohol into the corresponding ketone, genation has a boiling point considerably remote which comprises heating the alcohol under pres from that of the camphor formed. sure in the liquid phase with an aromatic hydro '11. The process of converting a secondary carbon in the presence of a hydrogenation cata alcohol into the corresponding ketone which 10 lyst, the quantity of aromatic hydrocarbon being comprises heating the secondary alcohol in the 85 not less than that theoretically required for com liquid phase with an unsaturated cyclic hydro plete reaction with all of the hydrogen liberated carbon and a hydrogenation catalyst at a pres during the reaction. sure su?icient for hydrogenation of the unsatu 5. The process of converting a terpene second rated cyclic hydrocarbon under the conditions of 15 ary alcohol into the corresponding ketone, which reaction, the unsaturated cyclic hydrocarbon be 90 comprises heating the alcohol under pressure in ing present in a proportion in substantial excess the liquid phase with an aromatic hydrocarbon of that theoretically required for complete re which is a member of the group consisting of action with all of the hydrogen eliminated from benzene and homologues of benzene, and in the the secondary alcohol. ' presence of a hydrogenation catalyst, the amount 12. The process of producing camphor which 95 of aromatic hydrocarbon being equal to at least comprises heating a borneol, in the liquid phase, one-third the molecular quantity of the sec with benzene and a hydrogenation catalyst at ondary alcohol. a pressure su?icient for hydrogenation of the 6. A process of making camphor, which com benzene under the conditions of reaction, the ' prises heating a borneol in‘ the liquid phase in a benzene being present in a proportion in substan 100 closed vessel in the presence of an aromatic hy tial excess of that theoretically required for com drocarbon which is a member of the group con plete reaction with all of the hydrogen eliminated sisting of benzene and homologues of benzene from the borneol, and in the presence of a hydrogenation catalyst, 13. The process of producing camphor which the amount of aromatic hydrocarbon being equal ‘comprises heating a borneol, in the liquid phase, to at least one-third the molecular quantity of with benzene and a hydrogenation catalyst at borneol compound started with. a pressure su?icient for hydrogenation of the 7. The process of producing camphor in high benzene under the conditions of reaction, the yields, which comprises heating in the liquid amount of benzene being equal to about three phase one mole of a borneol with at least one-> to about six times the molecular quantity .the 110 third of a mole of benzene in the presence of a oretically required for complete reaction with all nickel catalyst in a closed vessel at about200° C. of the hydrogen ‘eliminated. from the borneol. 8. The process of producing camphor, which 14. The process of producing camphor which comprises heating in the liquid phase and under comprises heating isoborneol, in the liquid phase, , pressure one mole of a borneol with at least one with benzene and a hydrogenation catalyst con 115 third of a moleof benzene in the presence of a taining nickel at a temperature of about 200° C., hydrogenating catalyst. under a pressure of about 100 to 300 pounds per 9. The process of converting a secondary al square inch, the amount of benzene being equal cohol into the corresponding ketone which com to about three to about six times the molecular _, prises heating the secondary alcohol under pres quantity theoretically required for, complete re 120 sure in the liquid phase in- the presence of a action with all of the hydrogen eliminated from hydrogenation catalyst with an unsaturated cy the isoborneol. clic hydrocarbon which after hydrogenation has CLYDE O. HENKE. a boiling point remote from that of the ketone formed. ' 125

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