US2911442A - Production of oxygenated terpenes from alpha-pinene - Google Patents

Description

I PRODUCTION OF OXYGENATED TERPENES I FROM ALPHA-PINENE Joseph P. Bain and Wilbur Y. Gary, Jacksonville, Fla., assignors to The Glidden Company, Cleveland, Ohio, a corporation of Ohio 1 No Drawing. Application April Serial No. 352,291

30, 1 953 1i Claims. (Cl. 250-6315 T The present inventi on relates to the production of oxying a mixture ofe-pinene oxidation products substan-' tially free of secondary by-products which render 'diflrlcnlt the separation and purification of the pineneoxidation products.

j for producing a-pin ene oxide.

Still a further object is ducing optically active oxygenated terpenes Still another object is to provide an improved process '1 Other objects will be apparent to those skilled in the art from the following description of the invention.

It has been foundthat the foregoing objects can be accomplished when the air oxidation mixture is treated with a reducing agent under non-acidic and preferably reported that in the presence of air,'water and sunlight,

a pinene yields sobrerol, Beilstein, 6; 752. Also, a-pinene oxide'has been formed by the oxidation of a-pinene with perbenzoic acid. Oxidation by air orgaseous oxygen is an economically desirable means of oxida tion, but the steam decomposition of the oxidation mixture leaves much to be desired. It causesforinatioh of substantial quantities of'un'desirable products'and'produces,low yields of someof the desirable products;

" It is accordingly an objecti b f: the presentinvention to L products from a-pinene. U Another object. is to provide an improved process for. treating the mixture resulting from, the air-oxidation of a-pinene. H r

A further object is to producecertain hitherto unknown alcohols. 1

An additionalobjectis to provide a new method for the production of verbenol, verbenone and u-pinene oxide.

Still another, object is to providefa process forjproducprovide an improved process for producing oxygenated I a-pinene alkaline conditions. Whentreated in the preferred mannet, the reaction mixture can be fractionally distilled to produce oc-PiIJCIlC oxide, verbenol, verbenone and both the cisand trans-forms of the hitherto unknown alcohol, 3-pinene-2-ol. In addition to the afore-mentioned products, myrtenol and myrtenal can also be isolated.

As indicated, alkaline conditions are preferred for the decomposition of the initialfoxidation products. When excess sodium sulfite is employed, the reaction mixture should tend to remainalkaline due to hydrolysis of this salt of a weak acid. As the sulfite is consumed, the alkalinity induced by hydrolysis decreases so that alkalinity is maintained only. if excess sulfite is present. Thus, in the absence of sulfite the pH decreases, thus permitting, for

. example, hydration of. pinene'o'xide, which is attacked by distilled water. Further,- while perhaps water of pH 7.5 when cold'will not attack the oxide appreciably, that same water when hot would attack it. Further, if the sulfite employed were slightly acidic, it would become much more acidic onfbeingoxidized To avoid these undesirable possibilities, we prefer to add excess alkali, such as soda ash, caustic soda, etc. in small amount, suitably corresponding to 1 to-3% concentration in the aqueous phase. This alkalifurthermore would neutralize any acidity presi eat inthe pe'roxidized 'pinehe under treatment. .By use I verbenone of such a cheap safeguard, it is unnecessary to provide excess sulfite overthat required ton reduction and whose.

only purpose would be to maintain suitable alkalinity.

Thus, while nonacidity is necessary to our invention,

alkalinity is preferred. The reactions may be represented as follows? i VI ve'rbenehe VII pinene oxide to, provide a process for pro-i The, yields of the various products vary somewhat, .depending upon the conditions, but representative yields obtained are as follows, based on oxygenatedproducts:

I It is to be noted that the pinane structure was retained in the products. Thus, when optically active a-pinene is used, the products are optically active.

The oxidation. can be carried out over any suitable temperaturerange. Atlower temperatures, the reaction may be'quite slow, while at temperatures of 80-90 C., there is some decomposition of theoxidation products. We prefer temperatures between 40-60" C., and particularly about 50 C. The durationof the oxidation will vary according to the temperature, oxygen concentration in the oxidizing gas and the particular degree of oxidation desired. Preferably theoxidation is continued to a peroxide value between' about 1000 and about 2000 and the mixture then reduced, since at peroxide values below about 1000 the quantity of pinene per unit of oxidation product to be recovered and reused becomes burdensome, 'whereas peroxide values of over 2000 are more difiicult to obtain economically and without encountering undesirable by-products among the recovered'oxidation products. A pure terpene hydroperoxide has a theoretical peroxide value of about 12,000 as defined by Wheeler; Oil and Soap, 9 8911932), so that an air-oxidized a-pinene of peroxide value of 1500 would contain about 12.5% peroxides.

The peroxidized pinene and reducing agent are reacted until a low peroxide value is reacted, and afterseparation of the reduced organic layer, distillation and crystallization follow to recover unattacked pinene and the individual oxygenated derivatives. l

Any reducing agent capable of absorbing oxygenfrom the air can be used. We havefound sodium sulfite to be quite suitable, but other reducing agents, such as sodium sulfide, ferrous hydroxide, alkaline pyrogallol, pyr'oligneous acid made alkaline, etc. can be used. Any suitable temperatures can be used, preferably not'much above 80-90" C., since if the reduction is carried out with an aqueous system at atmospheric pressure, unnecessary distillation or reflux would occur at somewhat higher temperatures than these, and further, any pinene oxide that would be so volatilized would react with the water condensate unless the vapor and vapor, condensate were kept sufiiciently alkaline, as by means of a suitable .cin. tube) was produced by isomerization of very pure fl-pinene. This pinene contained about 3% camphene which-did not air oxidize and therefore increased in concentration in the recovered pinene recycled to a new oxidation. The a-pinene employed need not be of highest purity but such impurities as'fp-pinene and limonene, for example, will themselves oxidize and such oxidation products will accompany the u-pinene oxidation products in the recovery operation thereby rendering more difficult purification of some of the u-pinene oxidation products. The u-pinene does not require any special pretreatment as, for example, special dehydration beyond volatile base such as ammonia ,or an amine which might be incorporated in the reduction system. Whether any heat need be applied at thereduction step depends on the rate of reaction desired andon'the identity of the reducing agent, whether an aqueous reducing system substantially totally immiscible with the peroxidized pinene is employed and if such a system isemployed then upon the degree of agitation employedaridwhether emulsifiers are present or not. Cooling the reduction system' below ambient temperatures would be expensive and wevhave not found it necessary or desirable to perform 'ther'educ tions at lower than ambientteinperatures.

Good quality commercial a-pinenes are suitable as raw materials. If oxidation products of high optical activity or of a specific optical sign are desired, the tat-pinene used as raw material should be chosen accordingly. Both dextro-pinene and levo-pinene were oxi dized and the oxidation products converted by our methods. Levo-u-pinene of optical rotation, -36.8 10

EXAMPLE 1 Air was passed through u-pinene by means of an air distributor as the pinene was maintained at about 50:5 until the peroxide number rose to about 1000 to 1600. About 100 to 140 hours were required to attain this degree of oxidation when starting the oxidation from zero peroxide value. It was found, however, that gain in peroxide value accelerated throughout the run, and therefore it was convenient in processing large quantities of pinene to withdraw continuously or periodically part of the material as it reached a peroxide value of 1200 to 1600 and replace it with fresh pinene, so that the peroxide value did not fall below about 600 or exceed about 1600. The exit air-pinene vapor mixture was passed through and efficient condenser arranged so that condensed pinene was returned to the oxidation mixture and the air saturated with pinene vapor discharged to the atmosphere wasat about 30. The weight of peroxidized pinene'was about equivalent to that of the starting pinene. Air was not measured carefully, but the oxidation was considered to be proceeding satisfactorily when measurements showed that 15 to 30% of the oxygen available was being fixed by the pinene. Only traces of acids were formed on oxidation, generally less than 0.5% calculated as acetic acid. In order to avoid the possibility of acid affecting the course of the reaction or reacting with the oxidation products, about 1% sodium carbonate was added prior to air blowing in some experiments, but the effect was usually not marked unless the starting pinene was itself slightly acidic.

"; The peroxidized pinene was reduced by agitation with an excess of concentrated aqueous sodium sulfite solution at about to The time required to decrease the peroxide value to about 10 was about two hours.

The reduced product was then fractionated at about mm. pressure-to remove unreacted pinene, now somewhat'richer-in camphene which was present in the commercial pinene in amounts of the order of 1 or 2% and which did not oxidize appreciably. This unreacted crude pinene amounted to 70 to 80% of the charge when the pinene had been oxidizedto a peroxide value of about 1200, and was of quality'suit'able' for further oxidation. Theipressure was then reduced to 10 mm. and the frac- 90% ofithe oxygenated products were volatile under I l l v i i these conditions, and boiled overthe range 65 to 110. Fractions were regrouped according to composition as determined by analysis by infrared, methods, and further purification was accomplished by refractionation, or where applicable, crystallization was employed. The purity of all productsreported here is estimated to exceed 98%, as judged by infrared data on consecutive samples from efiicient fractionation and crystallizations.

(A) Pinene oxide (VII) boiled at 69 at 1-0 mm., 011 0.960, N 1.4668, and was readily purified by fractionation. When produced from l-ot-pinene, 04 3 6.8 cm. tube), the pinene oxide showed [M 106, and when produced from pinene of 1x +19.6 (10 cm. tube), the pinene oxide showed [al +57". These data are in good agreement with those of Prilezhaev, J. Russ, Phys. Soc. 61, 4-45-65 (1929), who first produced the product by perbenzoic acid oxidation of pinene and who reported B.P. 103-104 at 50 mm., d 0.9675, N 1.4715, and [0:1 97.8. The pinene oxide was further identified by hydration to sobrerol.

(B) Trans-3-pinene-2-ol (VIIIa). Fractions containing some transbut mainly cis-3-pinene-2-ol were cooled and centrifuged to remove most of the cis-form, and the resulting mother liquor was refractionated to obtain fairly pure transmaterial which was further purified by partial freezing and centrifuging. It was isolated in pure form only from the oxidation ofl-ot-pinene, B.P. 76 at 10 mm., freezing point 44 [0:1 :3 +24.4 (36% in heptane), N 1.4730, @1 0.9429.

Upon hydrogenation over platinum oxide at 30-60 pounds pressure, the theoretical quantity of hydrogen was absorbed corresponding to one double bond. The hydrogenated product after recrystallization from hexane showed [111 5.84 (18.2% in ether), and freezing point 57". A concentrated benzene solution of the hydrogenated product shaken with 35% sulfuric acid at about 30 for seven hours deposited crystals of cis-terpin hydrate, M.P. 116-l17. These properties are in good agreement with those reported by Wallach, Ann, 356, 239 (1907) for the pinane-Z-ol obtained by reaction. of nopinone with methyl magnesium iodide.

Upon shaking 10 grams of the trans-tertiary alcohol with ml. of 2.5% sulfuric acid at 50 for 30 minutes, the resulting product'was found to contain 70% verbenol of the same configuration as obtained in this work by direct oxidation of pinene, and no unreacted tertiary alcohol remained. I r f Since this lower boiling 3-pinene-2 ol possesses a lower refractive index and density than the higher boiling form; it has been assigned the trans-configuration, and the cis? configuration is' assignedto the higher boiling isomer.

(C) Cis-3-pinene-2-o1 was purified by fractionation, partial freezing of the richest fractions, and centrifuging. The'p urified product boiled at 83 at 10 mm., 314 0.9477, N 1.4776, freezing point 46, .cap. M.P.*-48-49 C.- From l-pinene oxidation the product. showed +'1'30.1 (2.7 grams diluted to 10 ml. with heptane).

{The optically pure forms of this alcohol are less soluble than the racernic form, and therefore. it was possible to isolate the levo form by repeated crystallization of the partly racemic alcohol produced by,oxidation of d-apiriene of +19.6 (10 cm. tube). The thus purified 1e o form showed [pt] 1 32.0 (2.47 grams diluted to 10 ml. with heptane).

Equal parts of dextroand levoforms were mixed to produce a,sam'pleof'the racemic product, freezing point 20,M.P, 19.5-20.-5. 1

Upon hydrogenation. of the levo-form,'one mole of hydrogen was absorbed, and the product, after recrystallization from hexane, melted at 7677, [M -24.7 (.3118 grams diluted to 10 ml. with methanol). Hydration of this product with 35% sulfuric acid yielded 'cis-terpin hydrate, M.P. 116-117". These data arev in goodragreemerit with those of Lipp, Ber., 56 2098 (1923), for the pinane-2-ol produced by permanganate oxidation of pinane.

When d-cis-3-pinane-2-ol was stirred with an equal volume of 1% sulfuric acid for lminute, the temperature rose to and infrared analysis showed the product to be 86% verbenol of the same configuration as that obtained in the course of this work by air oxidation of pinene. "On fractionation, the best cuts as judged by infrared analysis boiled-at 95.5 at 10 mm. and showed N 1.4898, 11 -162.8 (10 cm. tube), [111 -169.0. Simonsen gives -168.75. Melting point was 22.5

Oxidation of l-cis-3-pinene-2-ol (from d-pinene) with Beckmans chromic acid mixture produced an 80% yield of verbenone [M +269, the highest optical rotation for this compound encountered in the course of this work.

(D) Myrtenal (V) from l-pinene was isolated by repeated fractionation, having B.P. 91 at 10 mm., {x1 -14.3 N 1.5010, 41 0.9812. The extinction coeflicient, a, of the purest sample was 65.5 at its wavelength of maximum absorption, k 240 m in iso-octane. Further identification was made by conversion to the semicarbazone, M.P. 224.

'(E) Verbenol ('III). The product isolated from the l -ot-pinene boiled at 96 at 10 mm., 11 1.4889, [111 --151 (10 cm. tube). It was separated from small quantities of accompanying verbenone by partial crystallization and centrifuging, and then showed M.P. 22, d., 0.965, N 1.4894, 0 -157 (10 cm. tube), data in fair agreement with those recorded for trans-verbenol, There was no evidence of the presence of cis-verbenol among the oxidation products.

(F) Verbenone (11) could not be isolated by fractionation from the verbenol or myrtenol-rich fractions in a state of purity. Oxidation of mixed verbenol-verbenone fractions from l-u-pinene with Beckmans chromic acid yielded pure verbenone, B.P. 97 at 10 mm., N 1.4935, M.P. 10.2, 03 0.971, 1 246.4 (10 cm. tube). The extinction coefficient, at, was 51.6 at the wavelength of maximum absorption, A -240 ma.

When prepared in the samemanner from u-pinene, a +19.6 (10 cm. tube), verbenone showed M.P. 1, +129 10 crn. tube). I

(G) Myrtenol. IV) was-isolated as crude verbenonemyrtenol fractions, from whichmyrtenol could not be isolated satisfactorily by repeated fractionation or by extraction of verbenone by sodium bisulfite. It was found,

however, that such fractions could be first esterified with a slight excess of acetic anhydride, and then fractionated to yield pure verbenone and pure myrtenyl acetate. The

I benol derived from the l-o -pinene yielded a low-boiling myrtenyl acetate derived from l-pinene boiled at 105- 106 at 10 and possessed 11 0.9810, N 1.4700, 46 (10 cm. tube). 'Saponification: of the acetate yielded pure myrtenol, B.P. 102 atlO mm., d 0.974,

N 1.4942, -48.7 (10 cm. tube). These data are in good agreement with those of Schmidt, C.A., 37- 4716 (19 43) for l-myrtenol prepared by oxidation' of fl-a-pinene. i i

(H) Verbenene (VI). Refractionation of crude verfraction on several occasions. Refractionation of this material yielded pure verbenene, B.P. 92 at mm., 42 at 10 mm., N 1.4975, 11 0.881, +84.4 (10 cm. tube).. .These data are in good agreement with those reported by Blumann and Zeitschel, Ber., 54, 887 1921), for verbenene verbenol r verbenene was also produced by dehydration of pure verbenol with acids, and the product showed the same physical properties, including ultraviolet andinfrared absorption spectra. These facts, plus the fact that it could not be detected in the mixture resulting fronithe reduction step, indicate; that the verbenene was formed during the distillation-1 per square inch pressure and room temperature with a produced by dehydration of' .7 platinum oxide catalyst yielded a mixture of 26% a-pinene and 50% fl-pinene.

In Table I are given suflicient of the characteristic absorption bands in the infrared region for the various products to'pr'ovide identification.

Table I Infrared absorptionbands characteristic of pinene derivatives expressed as frequency in reciprocal centimeters: Transverbenol: 726,772, 823, 853; 898, 926, 933, 99s, 1026, 1139.

' Myrtenal: 699, 780, 801, 889, 910, 966, 1043, 1129, 1170,

EXAMPLE 2 a-Pinene was air oxidized substantially as described in Example 1 to a peroxide value of 1500. A 4300 cc. aliquot of the air oxidation mixture was. stirred with 2 liters of saturated sodium sulfite solution, warmed slowly to 85 C. and held there for 2 hours and 35 minutes, at which time the peroxide valuewas 62. The reaction was stopped at this point andthe oil layer, weighing 3753 grams, was then fractionated. The bulk of the unreacted a-pinene was removed at 100 mm. absolute pressure, after which most of the oxygenated products were fractionated at mm. Near the end of the distillation the pressure was reduced to 1-2 mm. to remove the last of the oxygenated products. The analytical results obtained from examination of the products resulting from the treatment are shown in Table II.

.EXAMPLE 3 Table II [oxygenated products recovered aspercent of oxygenated distillate.

Shown in parenthesis are percent of product recovered based on weight of crude air oxidized pinene of peroxide value about 1500.]

' Oxidation-product Example 2 Example 3 a-Pinene-oxlde. .2..- 15.4 3.23) 26.2 i 6.11) 3-Pinene-2-ols 12.1 2. 54) 25.0 5. 84) Verbenol 21.8 4. 58) 31.4 7.3 Verbenone-.- 12.1 2.54) 8.0 1.8 Pinocarveol 4.1(086) a-Oampholenaldehyd 3.3 0.69) Myrten 5 4 1. 26) Myrtenal ,0;2 0.04) Carveol 3.3 0.69) Not identified 27.7 5.91) 4.0 0. 91) Distillation residue 8.75) 2. 64) Recovered a-pinene (69.00) (68. 00)

Total 100.0 (98.83) 100.0 (93.97)

The difference between 100% and the total recorded in parentheses represents loss of product. in decomposing the peroxidized pinene and is due to handling loss, loss of product to the aqueous phase, etc.

EXAMPLE 4 7 5000 cc. of -air oxidized u-pinen e, peroxide number 1230, was stirred together with 5000 cc. ofpyroligneous acid made alkaline with sodium hydroxide. The temperature of the mixture rose to 71 C. without external heat.

The mixture wasthenwarmed t'o'90" C. for Z'hours with Percent a-Pi'nene oxide 7 25.4 3-pinene-2-ol 25.9 Verbenol 37.3

Other compounds, including Verbenone, myrtenol and myrtenal 11.3

air oxidized pinene, this Referred to the original becomes:

Percent a-Pinene oxide 3.72 3-pinene-2-ol 3.80} 9 29 Verbenol 5.49 Verbenone Trace Minor Compounds 1.65 Residue 2.45

EXAMPLE 5 Twenty-two hundred and forty milliliters of a-pinene which had bcen oxidized to a peroxide number of 1600 was added to a stirred ferrous hydroxide slurry produced by mixing a solution of 707 grams FeSO -7H O in 2 liters of water with 283 grams NaOi-I in 849 grams water. Upon adding the peroxidized turpentine to the dirty greenish reducing mixture a color change to brown-red began immediately and the temperature of the mass rose to 55 C. in a short time. The slurry becamesomewhat stiffer as the ferrous hydroxide was converted to ferric hydroxide. At the end of an hour and a half of stirring, the slightly exothermic reduction was about over and the temperature had decreased to 50 C. After standing overnight, the thick slurry was centrifuged and filtered to remove the solid ferric hydroxide and the oil layer of the filtrate which now had a peroxide value of only 9 was fractionated at mm. pressure at a low reflux ratio to recover high quality unchanged pinene. When the bulk of the pinene had been recovered, the reflux ratio was increased and the absolute pressure was decreased to 10 mm. for further distillation to recover fractions enriched in the pinene oxidation products. Analysis by infrared methods of the fractions which together with the residue weighed 441 grams showed that the products boiling above pinene consisted of:

1 Total of the two forms.

While the foregoing examples show the use of air as the oxidizing medium, any oxygen-containing gas, including pure oxygen, can be used to produce the oxidation mixture. Preferably, good contact between the oxidizing gas and the pinene is maintained and this may be provided by the use of gas distributor devices, 'by counter current flow, or other means. 7

The examples also all show alkaline conditions, and

this is a preferred condition. However, in some experiments, only about the calculated amount of sulfite was employed to accomplish reduction and in thesecases, optimum'results were not obtained. Apparently, one reason for this was because the pH of the aqueous phase decreased sufficiently during the conversion of sulfite to sulfate that the most sensitive components of the. oxidation mass, suchas pinene oxide, were attacked by the water. This undesirable result was not. encountered when sulfite was present in great excess or where a small amount of free alkali was present throughout the reduction step. Thus, in the broadest concept of the invention, neutral conditions are contemplated for the reduction. There are definite 'advantagesin maintaining alkaline conditions throughoutthe course of the reduction.

In general, it has not been found particularly advantageous to concentratethe peroxides by separation of pinene from peroxidized pinene prior to reduction of the peroxides. If such separation of pinene from peroxides and other oxygenated components of the initial oxidation mixture priorto reduction is desired, this result can be accomplished byemploying such methods as stripping off the pinene, or part of it, at low temperatures and pressures in .vacuo. Alternatively, the peroxidized pinene may be contacted with a solvent substantially immiscible with pinene but miscible with pinene oxidation products. Such a selective solvent is methanol, preferably containing a few percent water. Other suitable polar extraction solvents include ethanol, isopropanol, dioxane, acetone and mixtures of these, propylene glycol, etc., which may suitably contain some water or not depending on the exact nature of the selective extraction desired.

. The examples contain certain illustrations of purification of products by chemical means. It will, of course, be obvious to those skilled in the art that other means than those specifically mentioned can be employed for purification and/or separation of the various products. Thus, alcohol-carbonyl containing mixtures can be purified as to cheer morerof the constituents by treatment with reagents for the carbonyl group, such as hydroxylamine, semicarbazide, phenylcarbazide, Girards reagent, methyl alcohol, glycols, etc., and the reaction products then separated from unreacted material. Similarly, in addition to esterification, reagents for alcohol groups, such as boric acid, can be employed to effect either initial separations or purification of enriched fractions. The relative simplicity of the reduction mixture, as compared to those produced by the prior art, makes these methods feasible, the particular choice depending upon the circumstances and the possible value of the reaction products themselves.

As shown by the foregoing, the process of the present invention results in substantially increased yields of volatile oxygenated products which are readily recovered by distillation and crystallization. There is a minimum formation of undesirable secondary products, such as pinocamphone, pinocanveol, pinocarvone, carveol and aoampholene aldehyde. Thus when another aliquot of the oxidation mixture used in Examples 2 and 3 was decomposed by steam, the total percent by weight of pinocarveol, u-campholene aldehyde and carveol, based on the oxygenated distillate was 25.2%, as compared to the 10.7% of Example 2.

The process also results in the production of both the cisand trans-forms of 3-pinene-2-ol, which has not heretofore been described. This alcohol can be easily isomerized to verbenol in substantial yields. Verbenone can also be converted to verbenol. Since verbenol is also produced directly by the process in substantial quantities,

high yields of verbenol are obtainable from the oxidation products. Verbenol has been found to possess disinfectant properties. Thus, anemulsion of 80% of verbenol with 20% of green soap, 50% solids, was found when tested by the method of U.S.D.A. Cir. 198 (1931), when employed with Salmonella typhosa at 20 C., to

possess a phenol coeflicient of 5.5. This is comparable to the results produced when steam distilled pine oil is converted to a similar composition. 1 It is also to be noted that there is a substantial yield of pinene oxide produced, which product was not preyiously found among those produced when steam distilla: tion was employed to decompose the peroxides formed during the oxidation. Pinene oxide can be hydrated to sobrerol, and this then converted to carvone, which can in turn be converted to carveol by known procedures. While steam decomposition of the peroxides produces some sobrerol, the reaction is not easily controlled, and it is distinctly advantageous to treat the pinene-oxide under conditions specifically designed for the particular reaction desired. Moreover, steam decomposition of the oxidation products results in high yields of resinous materials and relatively small yields of volatile products.

I The process of the present invention also enables one to produce optically active materials, and in the case of the 3-pinene-2-ols to produce optically pure material, since in such a mixture the optically pure forms are less soluble than the racemic form.

As indicated, any reducing agent for peroxides can be used, provided the reduction is carried out under nonacidic, preferably alkaline, conditions. The temperature of the reduction is not critical and temperatures from 30 to 100 C. have been found suitable. It will, of course, be appreciated that temperatures suificiently high to cause appreciable pyrolysis of components of the mixture should be avoided for best yields and recovery of unreacted pinene.

The acid isomerization of the 3-pinene-2-ols described herein is more fully described and claimed in the COPEIld,

. ing application of Bain et al., Serial No. 368,210, filed July 15, 1953, now Patent No. 2,818,435, and the oxidation of theS-pinene-Z-ols to verbenone is more fully described in our copending application Serial No. 352,292, filed: April 30, 1953, now Patent No. 2,767,215. i Having described the invention, what isclaimed is: 1. The process for producing 3-pinene-2' ol and pinene oxide which comprises oxidizing u-pinene with gaseous oxygen under substantially anhydrous conditions to produce a mixture of oxidation products containing hydroperoxides and pinene oxide and decomposing the hydroperoxides in said mixture by treating the mixture of oxidation products with a reducing agent for peroxides under aqueous alkaline conditions, the amount of alkaline material being suflicient to maintain the alkaline condition throughout the reduction treatment, whereby there is produced a mixture containing 3-pinene-2-ol and pinene oxide.

2. The process for producing 3-pinene-2-o1 and pinene oxide which comprises oxidizing a-pinene with gaseous oxygen under substantially anhydrous conditions to produce a mixture of oxidation products containing hydroperoxides and pinene oxide, decomposing the hydroperoxides in said mixture by treating the mixture of oxidation products with a reducing agent for hydroperoxides underaqueous alkaline conditions, the amount of alkaline material being suflicient to maintain the alkaline condition throughout the reduction treatment, whereby there is produced a mixture containing 3-pinene-2-ol and pinene oxide, and fractionally distilling the reduction mixture to recover oxygenated products therefrom.

3. The process for producing 3-pinene-2-ol and pinene oxide which comprises oxidizing u-pinene with gaseous oxygen under substantially anhydrous conditions to produce a mixture of oxidation products containing hydroperoxides and pinene oxide, decomposing the hydroperoxides in said mixture by treating the mixture of oxidation products with areducing agent for hydroperoxides under aqueous alkaline conditions, the amount of alkaline material being sufiicient to maintain the alkaline condition throughout the reduction treatment, whereby there is produced a mixture containing 3-pinene-2-ol and pinene v1-1 oxide, and recovering.,3-pinene-2-ol by fractional distillation of the reduction mixture. v V

4. The process for producing 3-pinene-2-ol and pinene oxide which comprises oxidizing 'u-pinene with gaseous oxygen under substantially anhydrous conditionsto produce a mixture of oxidation products containing hydroperoxides and pinene oxide, decomposing thehydroperoxides in said mixture by treating the mixture of oxidation products with a reducing agent for hydroperoxides under aqueous alkaline conditions, the amount of alkaline material being sufficient-to maintain the alkaline condition throughout the reduction treatment, whereby there is produced a mixture containing 3-pinene-2-ol and pinene oxide, and recovering pinene oxide by fractional distillation of the reduction mixture.

5. The process for producing 3-pinene-2-ol and pinene oxide Which comprises oxidizing a-pinene with gaseous oxygen under substantially anhydrous conditions to produce a mixture of oxidation products containing hydroperoxides and pinene oxide, decomposing the hydroperoxides in said mixture by treating the mixture of oxidation products with a reducing agent for hydroperoxides under aqueous alkaline conditions, the amount of alkaline material being sufficient to maintain the alkaline condition throughout the reduction treatment, whereby there is produced a mixture containing 3-pinene-2 ol and pinene oxide, and recovering the 3-pinene-2-ol and pinene oxide by fractionaldistillation of the reduction mixture.

6. The process for producing 3-pinene-2-ol and pinene oxide which comprises oxidizing u-pinene with gaseous oxygen under substantially anhydrous conditions to produce a mixture of oxidation products containinghydroperoxides and pinene oxide, decomposing the hydroperoxides in said mixture by treating the mixture of oxidation products with a reducing agent for hydroperoxides under aqueous alkaline conditions, the amount of alkaline material being sufficient to maintain the alkaline condition throughout the reduction treatment, whereby there is 'produced-amixture containing 3-pinene-2-ol and pinene oxide, and recovering fromthe reduction mixture frac- 1'2 tions of successively increasingboilingpoint enriched in pinene oxide, 'trans-3-pinene-2-ol, cis-3-pinene -2-ol, myrtenal, verbenol, verbenone and rnyrtenol, respectively.

7. The process of claim 2 in which a fraction enriched in verbenol is recovered.

8. The process of claim 7 in which a recovered fraction enriched in verbenol but containing some'verbenone is subjected to partial crystallization and separation of the crystallized material from the mother liquor.

9. The process of claim 2 in which a fraction enriched in verbenone is recovered. v

10. The process of claim 2 in which the a-pine'ne is optically active. 4

11. The process of claim 1 in which the oxidation is carried to a peroxide value of between about 1000 and about 2000.

References Cited in the file of this patent UNITED STATES PATENTS 2,302,467 Palmer et al. Nov. 17, 19:42 2,376,369 Lister May 22, 1945 2,392,413 Rummelsburg Jan. 8, 1946 2,484,841 Lorand Oct. 18, 1949' 2,535,345 Bishop et a1 Dec. 26, 1950 2,632,774 Conner et al. Mar. 24, 1953 2,735,870

Fisher et al Feb. 21, 1956 OTHER REFERENCES I 1 pp. 4-8. p

Claims (1)

1. THE PROCESS FOR PRODUCING 3-PINENE-2OL AND PINENE OXIDE WHICH COMPRISES OXIDIZING A-PINENE WITH GASEOUS OXYGEN UNDER SUBSTANIALLY ANHYDROUS CONDITIONS TO PRODUCE A MIXTURE OF OXIDATION PRODUCTS CONTAINING HYDROPEROXIDES AND PINENE OXIDE AND DECOMPRISING THE HYDROPEROXIDES IN SAID MIXTURE BY TREATING THE MIXTURE OF OXIDATION PRODUCTS WITH A REDUCING AGENT FOR PEROXIDES UNDER AQUEOUS ALKALINE CONDITION, THE AMOUNT OF ALKALINE MATERIAL BEING SUFFICIENT TO MAINTAIN THE ALKALINE CONDITION THROUGHOUT THE REDUCTION TREATMENT, WHEREBY THERE IS PRODUCED A MIXTURE CONTAINING 3-PINENE-2OL AND PINENE OXIDE.