Pinenes from Turpentine

Many terpenes are derived from renewable plant oil resources like essential oils. a-Pinene and -pinene from turpentine may be the best known examples, because they represent a very large volume. Turpentine was originally obtained from pine trees by tapping gum oleoresin from the stem of the living trees followed by steam distillation of the crude oleoresin and subsequently separation into rosin and turpentine by distillation. The ratio of a-pinene to -pinene in this turpentine varies considerably and depends a lot on the pine species from 

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Synthesis from a-Pinene. a-Pinene from turpentine oil is selectively hydrogenated to cis-pinane [35], which is oxidized with oxygen in the presence of a radical initiator to give a mixture of ca. 75% cis- and 25% tran -pinane hydroperoxide. The mixture is reduced to the corresponding pinanols either with sodium bisulfite (NaHS03) or a catalyst. The pinanols can be separated by... 

Scheme 13.1 shows the main commercial chemical pathways based on a-pi-nene and -pinene from turpentine. These pathways lead to four important target molecules or groups of molecules. These are the terpineols, menthol, cam-... 

Most menthol is isolated from peppermint oils, especially from crude oil from Mentha arvensis from India. But menthol can also be prepared by chemical synthesis. There are two important commercial processes for the synthesis of menthol. One is based on a renewable resource, /1-pinene from turpentine, and the other on m-cresol from petrochemical origin (Scheme 13.3). 

CAMPHOR The drug from the essential oil, obtained by steam distillation of the wood from Cinnamomum camphora (L.), J.Presl, belonging to the family Lauraceae, a high tree that is cultivated mainly in Taiwan. The production of natural camphor (optically active) has been replaced by synthetic camphor (racemate), which is synthesized from a-pinene (from turpentine oil). 

C, b.p. 156 C. The most important of the terpene hydrocarbons. It is found in most essential oils derived from the Coniferae, and is the main constituent of turpentine oil. Contains two asymmetric carbon atoms. The (- -)-form is easily obtained in a pure state by fractionation of Greek turpentine oil, of which it constitutes 95%. Pinene may be separated from turpentine oil in the form of its crystalline nitrosochloride, CioHigClNO, from which the ( + )-form may be recovered by boiling with aniline in alcoholic solution. When heated under pressure at 250-270 C, a-pinene is converted into dipentene. It can be reduced by hydrogen in the presence of a catalyst to form... 

Uses ndReactions. Some of the principal uses for P-pinene are for manufacturing terpene resins and for thermal isomerization (pyrolysis) to myrcene. The resins are made by Lewis acid (usuaUy AlCl ) polymerization of P-pinene, either as a homopolymer or as a copolymer with other terpenes such as limonene. P-Pinene polymerizes much easier than a-pinene and the resins are usehil in pressure-sensitive adhesives, hot-melt adhesives and coatings, and elastomeric sealants. One of the first syntheses of a new fragrance chemical from turpentine sources used formaldehyde with P-pinene in a Prins reaction to produce the alcohol, Nopol (26) (59). 

Terpin hydrate [2451-01-6] (10), one of the most weU-known expectorants, is isolated from cmde pine rosin left after the distillation of volatile terpene hydrocarbons and alcohols. It is also manufactured from turpentine (a-pinene) by acid-cataly2ed hydration. Terpin hydrate may exist as cis and trans isomers, but only the cis isomer forms a stable, crystalline monohydrate. Terpin hydrate is available in the United States only in prescription products. 

It is obtained from American turpentine as dextro-o-pinene, or from French turpentine as laevo-a-pinene. It is also obtained in a very pure form as dextro-a-pinene from Greek oil of turpentine. Optically inactive o-pinene can be obtained by regeneration from the nitrosochloride. The purest specimens of a-pinene yet obtained have the following characters —... 

By oxidation of d- and Z-pinene of high rotatory power, Barbier and Grignard obtained the optically active forms of pinonic acid. Z-pinene from French turpentine oil (boiling-point 155 to 157 , od - 37 2 157 to 160 , tto - 32 3°) was oxidised with permanganate. From the product of oxidation, which (after elimination of the volatile acids and of nopinic acid) boiled at 189 to 195 under 18 mm. pressure, Z-pinonic acid separated out in long crystalline needles, which, after recrystallisation from a mixture of ether and petroleum ether, melted at 67° to 69 . The acid was easily soluble in water and ether, fairly soluble in chloroform, and almost insoluble in petroleum ether. Its specific rotation is [a]o - 90-5 in chloroform solution. Oximation produced two oximes one, laevo-rotatory, melting-point 128 and the other, dextro-rotatory, melting-point 189° to 191°. 

Pinene hydrochloride is prepared in the usual manner from turpentine, and this is allowed to react with acetate of silver. Isobornyl acatate is formed, which is hydrolysed, and the isoborneol oxidised to camphor. Acetate of lead is also used, as is also acetate of zinc. 

Until the work of Zavarin and Snajberk (1973a), the only chemical information available on the bristlecone pines was the report by Haagen-Smit et al. (1950) that the major component of P. longaeva (at that time referred to as P. aristata) turpentine was a-pinene and, interestingly, that the optical rotation of a-pinene from P. longaeva and southern specimens of P. balfouriana was dextro rotatory (h-26.12° and +23.72°, respectively), whereas that of northern specimens of P. balfouriana was levo rotatory (-10.23°). 

Several unsaturated cyclic hydrocarbons, having the general formula C]qHj5, occur in certain fragrant natural oils that are distilled from plant materials. These hydrocarbons are called terpenes and include pinene (in turpentine) and limonene (in lemon and orange oils). 

The three main platform molecules employed in terpene chemistry are a-pinene and / -pinene, which are extracted from turpentine oil (350000 t a-1) a co-product of paper pulp industry, and limonene extracted from citrus oil (30000 t a-1). 

Walter Reed-Wistar and Charles River male adult rats were exposed to oral doses of turpentine or to turpentine vapors, which consisted of a- and p-pinene. These exposures were followed by oral administration of heptachlor epoxide or of one of three pesticides, paraoxon, heptachlor, or parathion, or by an intraperitoneal injection of hexobarbital. The studies revealed that pretreatment with turpentine reduced hexobarbital sleeping time, reduced the parathion LDso, and increased the heptachlor LDso. The paraoxon and heptachlor epoxide LOo values were unchanged. a-Pinene and P-pinene vaporized from turpentine had no effect on either hexobarbital sleeping time or parathion, paraoxon, or heptachlor epoxide mortality but did increase the heptachlor LDso (Sperling et al. 1972). The authors speculated that increases in hepatic microsomal enzyme activity are responsible for these differences. 

Pine oil is a mixture of terpine-derived alcohols. It can be extracted from pine but is also synthetically made from turpentine, especially the a-pinene fraction, by reaction with aqueous acid. It is used in many household cleaners as a bactericide, odorant, and solvent. The major constituents of pine oil are shown here. 

The reasons to use raw materials from renewable resources can be various. When a natural flavour ingredient has to be prepared, a natural raw material is essential, and natural raw materials are renewable, because they come from plants, animals or fermentation. For nature-identical flavour ingredients, a renewable raw material can be a good choice from a chemical point of view and quite often also from a cost point of view if turpentine is readily available in a country with limited or no petrochemical resources, -pinene from the renewable source is cheaper than chemically synthesised -pinene. A manufacturer chooses only for sustainable production if it is remunerative and at least as attractive as other options. 

Camphor is of considerable importance technically, being used in the manufacture of celluloid and medicinal products. It is manufactured industrially from a-pinene, obtained from turpentine, by several processes (66-107) which differ mainly in detail. Synthetic camphor is usually obtained as the racemic modification. The formation of camphor involves the Wagner-Meerwein rearrangements, e.g. ... 

In all examples of the palladium-catalyzed telomerization discussed up till now, the nucleophile (telogen) can be considered renewable. The taxogens used (butadiene, isoprene), however, are still obtained from petrochemical resources, although butadiene could, in principle, also be obtained from renewable resources via the Lebedev process that converts (bio)-ethanol into 1,3-butadiene. Limited attention has been given in this respect to the great family of terpenes, as they provide direct access to renewable dienes for telomerization. In particular, those terpenes industrially available, which are derived mostly from turpentine, form an attractive group of substrates. Behr et al. recently used the renewable 1,3-diene myrcene in the telomerization with diethylamine, for instance [18]. The monoterpene myrcene is easily obtained from (3-pinene, sourced from the crude resin of pines, by pyrolysis, and is currently already used in many different applications. 

Terpenes are obtained either by processing wood in the kraft process in paper production or by collecting resins and turpentine from conifers. The scale of produced terpenoids in comparison with fats and oils is small. Applications for terpenes are in pure form as solvents, as odorous substances, or in dyes. Most terpenoids contain double bonds which are readily available to perform chemical reactions. A widespread component of turpentine is a-pinene, from which many fragrances are produced. A further often-used resource is myrcene, which is obtained by pyrolysis of (3-pinene. Myrcene is an important base chemical to produce, for example, the fragrances nerol and geraniol [7]. 

Polyterpene resins are related to the oldest reported polymerization, as they were first observed in 1789 by Bishop Watson by treatment of turpentine with sulfuric acid [92]. Commercial polyterpene resins are synthesized by cationic polymerization of /3- and a-pinenes extracted from turpentine, of rf,/-limonene (dipentene) derived from kraft-paper manufacture, and of d-limonene extracted from citrus peels as a by-product of juice industry [1,80,82,93]. The batch or continuous processes are similar for the three monomers. The solution polymerization is generally performed in mixed xylenes or high boiling aromatic solvent, at 30-55° C, with AlCl3-adventi-tious water initiation. The purified feedstream (72-95% purity, depending on monomer) is mixed in the reactor with solvent and powdered A1C13 (2—4 wt% with respect to monomer), and then stirred for 30-60 min. After completion of the reaction, the catalyst is deactivated by hydrolysis, and evolved HC1 is eliminated by alkaline aqueous washes. The organic solution is then dried, and the solvent is separated from the resin by distillation. 

These reactions, in principle, are those used in the commercial synthesis of camphor and show the relationship of the intermediate products. The details of the methods actually used are various and may be found by consulting larger books. The pinene is obtained from turpentine, the turpentine itself being used directly. The production of synthetic camphor from this source has been developed very much during recent years. 

The most widespread use of limonene has been as a raw material for the manufacture of adhesives, such as the glue on labels and envelopes. Terpene monomers used for resin production are pinene, dipentene from turpentine and rf-limonene. Waterless hand cleaners produced from d-limonene were among the first to replace solvents such as mineral spirits. Although ri-limoncnc is more expensive than mineral spirits and kerosene, the former is used because of the pleasant citrus aroma and its claimed biodegradability (Coleman, 1975 Kutty et al., 1994). Many flavor chemicals... 

Among these molecules, only a few have been the subject of extensive studies related to their polymerization, namely those which can be readily isolated in appreciable amounts from turpentine a-pinene, P-pinene, limonene and, to a lesser extent, myrcene [5]. 

Isobomeol to Camphor. Nitric add has been widely used in the production of synthetic camphor from turpentine. The commonly accepted general practice for this manufacture (the one adapted by Gubehnann fw use in this country) involves the following steps (1) distillation of turpentine to obtain pinene, (2) saturation with HCl gas to obtain bomyl chloride, (3) hydrolyzing this to obtain camphene, (4) esterifying camphene to isobomyl acetate, (5) saponification to isobomeol, and (6) oxidation to camphor. 

Classification Unsat. alicyclic hydrocarbon Definition Volatile essential oil obtained by distillation and rectification from turpentine, an oleoresin obtained from Pinusspp., contg. pinene and diterpene Formula C,oH,6... 

CAS 8006-64-2 (steam distilled) 8052-14-0 9005-90-7 977022-00-6 (rectified) EINECS/ELINCS 232-350-7 232-688-5 UN 1299 (DOT) 1300 (DOT) FEMA 3088 Synonyms Gum turpentine Pine balsam Pine gum Purified gum spirits Spirits of turpentine Spirit of turpentine Terebenthine Turpentine gum Turpentine oil Turpentine oil, rectified Turpentine oil, rectifier Turpentine, purified Turpentine, rectified Turpentine, steam distilled Wood turpentine Classification Unsat. alicyclic hydrocarbon Definition Volatile essential oil obtained by distillation and rectification from turpentine, an oleoresin obtained from Pinus spp., contg. pinene and diterpene Formula CioHi6... 

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