US1210681A - Hydrogenizing olefinic terpene derivatives. - Google Patents

Description

are a CARL PAAL, OF LEIPZIG, GERMANY.

HYDROGENIZING OLEFINIC TERPENE DERIVATIVES.

miihleniveg, Leipzi Kingdom of Saxony,v

German Empire, have invented a new and useful Improvement in Hydrogenizing ()lefinic Terpene Derivatives; and I do hereby declare the following to be a full, clear and exact description of the same.

The present process for hydrogenizing olefinic terpene derivatives has the purpose, to obtain from olefinic terpene derivatives containing oxygen-hydrogen, groups (for instance the alcohol-, aldehydeor acidgroup) the corresponding saturated compounds while maintaining the oxygen-hydrogen groups in unchanged state.

The process consists essentially in that the olefinic terpene derivatives in presence of so called adhesion compounds of the platinum metal group are subjected in neutral medium to the action of hydrogen.

I may use as adhesion compounds of the platinum metal group the colloidal metals according to C. Paal (Bari/2km dc!" Deuts/rhen ("hemisclzcn Gesell-s'cimft volume 37 page 124 (1904); "olume 38'page 1398 (1905) German Patent 157172).

More suitable for carrying out the process are the adhesion compounds obtained by precipitating platinum metals on pulverm lent. indifferent substances free of anticatalytic action. which platinum metals are retained by the pulverulent particles on behalf of the adhesion (adsorption) action, (see on such compounds Bem'chfe (.Zcr fhnzzsvrhm'i Uhcmv'sclnm GeseZZscha-ft volume 4 page 1013 (1911); volume 46 page 3060 1913)). By the use of the said platinum metal compounds as catalysts in the action of hydrogen one succeeds to hydrogenize olefinic terpenederivatives without forma-- tion of by-products, The olefinic terpene derivatives in question with one-double carbon linkage can be transformed, by transition into the single-linkage 'form, into the saturated compounds, While those with two double carbon bonds can be converted-by stages into the diand tetra-hydroderivatives, Without any change taking place in the carbine], carboxylic or aldehyde group. In this way, according to the working conditions, geraniol can be transformed into citronellol (dihydrogeraniol) or tetrahydrogeraniol, linalool into dior tetra-hydroh- Specification of Letters Patent.

Patented Jan. 2, 1917.

Application filed July 18, 1914. Serial No. 851,794.

nalool, citral into citronellal (dihydrocitral) or tetrahyrlrocitral, geranic acid into citronellic acid (dihydrogeraniuni-acid) or tetrahydrogeranium acid; while the olefinic terpene derivatives containing only one double linkage, as citronellol, eitronellal and citronellic acid can he transformed into their saturated dihydro-compmmds.

The catalysts especially suitable for my process, containing as large a surface as possible, consisting of the platinum metals or their protohydroxi'ds, may be obtained by being deposited from the aqueous solution of Plltilllllllilltitill salts on finely pulverulent substances having with reference to their finely pulverulent state a large adhering surface. Metals specially adapted to serve as catalyzer carriers are: magnesium, nickel and cobalt, treated, in the form of fine powder, with a solution of a palladiumor platinum salt, the palladium or platinum being precipitated as a thin metallic coating on the powdered metal. Other suitable mate" rials are the finely pulverulent oxids of the said metals, as precipitated magnesium hydroxid, magnesium or calcium carbonate, \vhich react with solutions of salts of palladium or divalent platinum, to form the protohydroxids, Pd(()l'l) and Pt(()H) the latter being deposited, as. a thin adherent stratum, on the powders; and finally inert, finely powdered insoluble substances, such as barium sulfate, kieselguhr, coal, Wood dust, sawdust, cellulose powder and the like can also serve as catalyzer carriers, these being saturated with the palladioor platinosalt solution and then treated with dilute soda. solution, thus precipitating the respective protohydroxids, as thin coatings, on the powders. The relative proportions between catalyzer carrier and catalyzer are preten ably chosen so that the former contain ().5l% of palladium, as such or as protohydroxid, or 12% of platinum, also as metal or protohydroxid.

()ther suitablecatalysts for hydrogenizing oletinic terpene derivatives with hydrogen are the colloidal adhesion platinum metals prepared according to the Paal process in using sodium protalbinate (Bem'chte rlc'r' Dent-when Chemise/Len G'cscZZsc/mft volume 37, page 124 (1904); volume 38, page 1398 (1905)). The said compounds contain the metals only in a very finely divided state. The last named modification of my process by using the colloidal compounds according to Iaal is more cxpen' sive, than the use of the adhesion compounds on pulverulent substances, I because in the separation of the reaction products the colloid inust be precipitated by acid, in which operation the colloid is transformed into the irreversible gel. The acid may also have a transforming action on the half hydrogenized olel'inic terpene derivatives. Because, however, the hydrogenizing process itself is carried out in a neutral medium and the acid is added only after thefinished reduction, one is able to reduce the transforming action of the acid to a minimum in avoiding the use of a surplus of acid. For these reasons it is even possible to obtain good technical results in using the colloids according to laal,

The use of catalysts in which the. platinum metals have been imparted to as large surface as possible either by adhesion on .pulverulent substances or by transformation in the colloidal state according to the quoted method of laal presents furthermore the advantages that the catalyst can be separated from the reduction product, simply and without loss, by filtration; and also that only very small quantities of the expensive platinum metals are required.

One part of palladium or two parts of platinum will suffice-to reduce a thousandfold quantity of an olefin terpene derivative. The process is also capable of being carried out with still smaller quantities of cataly-zer, though in such case it takes more time, the velocity of the reaction depending on the quantity'of the catalyst, and also. to a smaller extent, on the nature of the terpene derivatives, the doubly unsaturated forms of which are more easily and quickly reduced than those which have only one double carbon linkage. The reduction proceeds at ordinary temperature and atmospheric pressure, though a positive pressure of 2-4 atmospheres of hydrogen has an accelerative effect on the process, without, however. being essential. The liquid olelinic terpene alcohols andaldehydes are also h v-.

drogenized without the application of any diluent, though it has been found advantageous to dilute them with a multiple volume of methylor ethyl alcohol.

In using colloidal platinum metals according to laal aqueous solutions of the same are mixed with the alcoholic solution of the terpene derivative to be hydrogenized. Substances with an anticatalytic ac- 'tion, such as many metals and their compounds, for example lead, zinc. and the like; also carbon disulfid, chloroform, volatile compounds of arsenic and phosphorus, sulfureted hydrogen and mineral acids; must be avoided, Thehydrogen used must also be free from anticatalytie constituents.

One has already proposed to use platinum black in hydrogenizing terpene derivatives (Willstiitter, Bcrz'chte der [)cutschcn Uhcmiscken Gescllsclmftvolume 41, page 1475). In using platinum black one does however not succeed in maintaining the oxygen hydrogen group in unchanged state, whereas hydrocarbons are formed in a high amount. -For other hydrogenizing processes one has used palladium chlorid (American Patent 1063746 Skita) or solid platinum salts (American Patent 1023753 Paal). In this way however it is impossible to hydrogenize the olelinic terpene derivatives, because in the hydrogenizing process acid is liberated which has a decomposing or transforming action on oletinic terpene derivatives.

Ewamplcs.

l. lrof ressi've reduction of oitml, gemm'ol and lint/loot, t0 the correapomlin dihy drocump'oumls-JMr the semi-reduction, 1000 parts of one of the above named, freshly distilled, doubly unsaturatedalcohols or aldehydes are mixed with a 7-8 fold-volume of 9 methylor ethyl alcohol (referred to the volume of the terpene derivative), whereupon '1 partor if the reduction is desired to be effected very quickly, 2 parts-of palladium or alternatively 2 or 4 parts of plati- 9 num, are added in the form of one of the catalyzers mentioned above. Nevertheless, as already stated, the reduction can also be carried on with smaller quantities of palladium or platinum, with a longer expenditure 1 of time. a

Palladium protohydroxid or platinum protohydroxid deposited on finely powdered calcium carbonate, has been found specially effective, used either direct or after careful 1 reduction with, hydrogen in the cold. The mixture is next placed in a closed vessel, taking care to prevent contact with any anticatalytic metals; and the amount of 1o hydrogen required for the semi-reduction is. intrmluced, at the ordinary temperature and with constant process is stopped at once. The reduction is still more rapid when performed in an autoclave provided with stirring mechanism and 1 a pressure gage, the vessel being evacuated, to remove the air, when chargedwith t he catalyzer-aml the substance to be reduced, whereupon hydrogen is admitted under a positive pressiu'e of 2-4 atmospheres, the 1 stirrers are set in operation, and'the reduction is stopped when the fall in pressure, in-

dicated by the gage, shows that the calculated quantity of hydrogen for performing the semi-reduction, has beenconsumed. The 1 semi-reduction of the doubly unsatlu'ated geranic acid, C,.,H,',,O to dihydrogeranic acid C H O (inactive citronellicacid) is I ellected in the manner already described, With the slight modification that, inorder to 1 stirring, whereupon the. 7

- hydrolinalool,

prevent esterification, use is made of either the freshly distilled, undiluted acid, or else of the said diluted with a multiple volume/ of aqueous alcohol, with palladium protohydroxid. ld(()l l) or platinum protohydroxid, lt(()l-I) as catalyzer, which, however, in view of the fact that the acid acts.

on calcium carbonate, are precipitated, not on this latter substance, but on a chemically inert catalyzer carrier, for example barium sulfate. the precipitated Id(()H) or I t(()ll) being reduced with hydrogen before use. I"d(()I'l) or l.t(()ll) precipitated on calcium carbonate can, however, also be used, after previous reduction to metal by hydrogen, provided the ,qeranic acid be employed in the form of an aqueous solution of its alkali salt. The reaction products are isolated in known lnanner. For the purpose of purification they are distilled in a partial vacuum. In this way there is obtained from citral (C II KX), dihydrocitral inactive citronellal ((l dl fi) boiling point at 10 mm.=79.81; D ZZ= 0.8535. Geraniol (C II O) furnishes dilrvdrogcraniol inactive citronellol ((,,,l"l. boiling point at 10 mm.::)9; D'Z=0.8488; melting point of the dihydrogeraniol-pyroracemate-scmi-carbazonc 112-l13 (Bouveault, 7mm. (ic'ntr. Blazft, 1904, II, 440, In. 1). 112). Linalool ((H H O) furnishes dihydrolinalool ((I,,H,,,O) boiling point at 15mm.:0-3-92l DZ=0.8579. Phcnylurcthane of the dim. p. 60. Geranic acid Il O furnishes dihydrogeranic acid l H O (inactive citronellic acid) b. p. 9 mm.=139131: D 2: =O.927f7.

11. Complete "reduction of the olcfim'c tar- 71mm alcohols and aZdekydcs.IVlu-.n the complete'reduction of the olefinic terpene alcohols and aldehydes is in question, the employment of previously calculated quantities of hydrogen is superfluous, because the process ceases when the carbon double linl ages in the molecules of the olefinic terpene derivatives have passed into the simple form. Under the working conditions stated, no further reduction takes place. The work is carried on in the way detailed in Exainple I. The complete reduction of the doubly unsaturated geranic acid C H O and the simply unsaturated citronellic acid C H 0 to the completely saturated, inactive telra-' hydrogeranic acid C H O (inactive dihydrocitroncllic acid) or to the optically active dihydrocitronellic acid, (Q,.,,H is also effected in the manner given in Example I, with the difference that the hydrogen is allowed to act until saturation is complete. By filtering them off from the catalyzer, which can then be used over agaim'the reduction products are obtained in quant ative amount. They are isolated in known &

manner, and purified by distillation in a partial vacuum. In this way, eitral, (1 11 0, and dihydrocitral (citronellal) (3 11 0, furnish tetrahydrocitral U II O, b. p. 16 mm.=8788; D}Z=O.83l. Geraniol, C l-l fi, and dihydro-geraniol (l,,,ll. furnish tetrahydro-geraniol, C I-I 0 bfp. 18 mm. =1l2-1l3"; D=O.S329. Linalool, C H O, and dihydro-linalool, U II O, furnish tetrahydro-linalool, C H O: b. p. 153 mm.=-89; l)=0.8327; (001F078. (lefranic acid, (,,,I'l,,,() furnishes tetrahvdrogeranic acid (J H O b. p. 10 mm.:1 l3- 134; D;=0.8$)9. Citronellic acid furnishes dihydrocitron'cllic acid. Q' H Q. (optically active tetrahydro-geranic acid): b. p. 9 mm. =133; (a) ,19 +4.58; DZZ=O.S95.

In comparison with the previously known processes mentioned above, and with that of German Patent 230724, the process exhibits the following technical advantages: (1.) Only very small quantities of the expensive palladium or platinum, acting as the hydrogen carrier are required; The reduction product can be separated from the catalyzer in the simplest manner, by filtration, not even a trace of the catalyzer is lost, and the latter is fit for use over againwithout further treatment: (3.) In the case of doubly unsaturated compounds the reduction may be partial (scmi-) or complete, as desired; (4.) The process goes on quantatatively at the ordinary temperature, without the formation of by-products; The reduction occurs in a perfectly neutral solution so that the transpositions and condensations to which the olefinic terpene derivativcs are liable under the influence of alkalies or acids cannot take Place.

I claim 1. The process for preparingsaturated aliphatic terpene derivatives containing oxygen-hydrogen groups which consists in mixing olefinic terpene derivatives containing oxygen-hydrogen groups with adhesion compounds of the platinum metal group free of acid and introducinghydrogen at ordinary temperature in a, neutral medium intothe said mixture.

2. The process for preparinn' saturated aliphatic terpene derivatives containlng oxygen-hydrogen groups which consistsln mixing olefinic terpcne derivat ves conta ning oxygen-hydrogen groups with adhesion compounds of the platinum metal group free of acid and introducing hydrogen at ordinary temperature under higher than atmospheric pressure in a neutral meduun into t1. said mixture.

Z-L'The process for preparing saturated aliphatic terpene derivatives containing ox gen-hydrogen groups which consists 1n dissolving olefinic terpene derivatives con taining oxygen-hydrogen groups in organic aliphatic terpene derivatives containing oxygen-hydrogen groups which consists in mixing olefinic terpene derivatives containing oxygen-hydrogen groups with substances of the platinum metal group free of acid previously deposited on ditferent pulverulent substances and introducing hydrogen at ordinary temperature intothe said mixture.

The process for preparing half saturated aliphatic ter 'iene-derivatives containing oxygen-hydrogen groups which consists in mixing olefinic terpene derivatives containing oxygen-hydrogen groups and twodouble linkages of carbon with adhesion compounds of the platinum metal group free of acid and introducing hydrogen only in sufficient amount for hydrogenizing one double linkage of carbon at ordinary temperature in a neutral mediuminto the said mixture? 6. The process for preparing half saturated aliphatic terpene derivatives containing oxygen'hydrogen groups which consists in mixing olefinic terpene derivatives containing oxygen-hydrogen groups and two double linkages of carbon with adhesion compoundsof the platinum metal group.

free of acid and introducing hydrogen only in sufiicient amount for hydrogenizing one double linkage of carbon at ordinary temperature under higher than atmospheric pressure in a neutral medium into the said mixture.

7. The process for preparing half saturated aliphaticterpene derivatives containing oxygen-hydrogen groups which consists in dissolving olefinic terpene derivatives containing oxygen-hydrogen groups and two double linkages of carbon in organic solvents, mixing the said solution with adhesion compounds of the platinum metal group free of acid and introducing hydrogen only in sufficient amount for hydrogenizing one double linkage of carbon at ordinary telnperature under higher than atmospheric pressure in a neutral medium into the said mixture.

8. The process for preparing half saturated aliphatic terpene derivatives containing oxygen-hydrogen groups which consists in dissolving olefinic terpene derivatives containing oxygen-hydrogen groupsand two double linkages of carbon in organic solvents, mixing the said solution with substances of the platinum metal group free of acid previously deposited on indifferent pulverulent substances and introducing hydrogen only in sufficient amount for hydrogenizing one double linkage of carb'in at ordinary temperature under higher than atmospheric pressure into the said mixture.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

CARL PAAL. Witnesses:

RUDOLPH FRICKER, ALICE DUNGER.