Dipentene turpentine

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... 

By oxidation with permanganate it forms pinonic acid, C,oH,<503, a monobasic acid derived from cyclobutane. With strong sulphuric acid it forms a mixture of limonene, dipentene, terpinolene, terpinene, camphene and p-cymene. Hydrogen chloride reacts with turpentine oil to give CioHijCl, bomyl chloride, artificial camphor . 

Terpenes, specifically monoterpenes, are naturally occurring monomers that are usually obtained as by-products of the paper and citms industries. Monoterpenes that are typically employed in hydrocarbon resins are shown in Figure 2. Optically active tf-limonene is obtained from various natural oils, particularly citms oils (81). a and P-pinenes are obtained from sulfate turpentine produced in the kraft (sulfate) pulping process. Southeastern U.S. sulfate turpentine contains approximately 60—70 wt % a-pinene and 20—25 wt % P-pinene (see Terpenoids). Dipentene, which is a complex mixture of if,/-Hmonene, a- and P-pheUandrene, a- and y-terpinene, and terpinolene, is also obtained from the processing of sulfate Hquor (82). 

A process of polymerization of isomerized a-pinene or turpentine with vinylbenzenes has been disclosed (105). a-Pinene or turpentine is isomerized by flash pyrolysis at 518 5° C in a hot tube reactor to yield a mixture of predominantly dipentene and i7t-alloocimene... 

The principal constitaenta of liussian turpentine are, according to Sohindeltaeiser, fl-pinene, sylvestrene, and dipentene. A little deifro-ti-... 

Turpentine is a mixture of CioHie volatile terpenes (hydrocarbons made of isoprene units). There are actually four different types and methods of making turpentine, including steam distillation of wood. The two pinenes, a and P, are major components of turpentine. Other compounds found in abundant amounts are camphene, dipentene, terpinolene, and A -carene. Although it has been replaced by petroleum hydrocarbons as paint thinners (lower price, less odor), turpentine is still a good solvent and thinner in many specialty applications. The use pattern for turpentine is as follows synthetic... 

The terpenes used were mainly /3-pinene fractions provided by DRT (Soci6td des Derives Rdsiniques et Terpeniques, Vielle-S Girons) and, for certain experiments a turpentine oil containing the main three terpenes a-pinene, /3-pinene, and A -carene. The /3-pinene fractions contained 80-90% /3-pinene, 2% a-pinene, 4-5% myrcene, 2-3% dipentene and 700-1500 ppm S. GC-MS analyses showed that sulfur impurities were composed of alkyl and alkenyl sulfides (mainly dimethyl sulfide), alkyl and alkenyl disulfides (mainly dimethyl disulfide), trisulfides, thiophene and alkylthiophenes (methyl, dimethyl, acetyl and tertiobutyl). 

Impregnation of cobalt and molybdenum (without sodium) increases largely the isomerizing activity of the catalyst the /3-pinene is then completely converted. The catalysts prepared with sodium molybdate and sodium hydroxide (Co-Mo-Na and Na-Co-Mo-Na) have lower isomerizing activities while their HDS activities are significantly increased. As in the case of alumina supported catalysts the sulfided CoMo phase protected by a double layer of alkaline ions on the carbon support gives the best results in HDS of /3-pinene. The behaviour of this catalyst was examined in desulfurization of the turpentine oil (40% a-pinene, 25% /3-pinene, 25% A -carene and 10% camphene + dipentene + myrcene, 1500 ppm S). The results are recorded in Table 6. 

According to Ref 2, camphor oil is a col, natural oil with characteristic odor, d 0.870 -1.040, nD 1.465-1.481 at 20° sol in eth, chlf insol in ale its chief constituents are pinene, camphor, cineol, phellandrene, dipentene, safrol eugenol. Derived by distg the wood of the Cinamonum camphora and separating the oil from solid camphor. Used as substitute for turpentine oil in varnishes, cheap soaps, shoe polishes, etc... 

Turpentine is a volatile oil consisting primarily of terpene hydrocarbons, having the empirical formula C10H,6. These 26 atoms can have many different arrangements, only six of which are present in appreciable amounts in commercial turpentines a-pinene (b.p. 156°C), /3-pinene (b.p. 164°C), camphene (b.p. 159°C), A3-carene (b.p. 170°C), dipentene (b.p. 176°C), and ter-pinoline (b.p. 188°C). The molecular configurations of some of these are shown in Fig. 28.20. 

The solution from the extractors is vacuum-distilled and the solvent recovered. The remaining terpene oils are fractionally re-distilled under vacuum and recovered as turpentine, dipentene, and pine oil. The nonvolatile rosin is of dark color and is upgraded by clarification methods, such as selective absorption of its solution (bed-filtering). 

Dipentene. Dipentene is present in the higher-boiling fractions of wood turpentine. It is used in paints and varnishes and as a penetrating and softening agent in rubber reclamation. 

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. 

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... 

Complex volatile hquids derived from flowers, stems, and leaves, and often the entire plant. They contain terpenes (pinene, dipentene, etc.) and are used chiefly for perfumery and flavorings. Usually resinous products are admixed with them. Turpentine is a highly resinous essential oil. 

Materials. Trans-stilbene (Fluka AG) and (+)-a-pinene (Aldrich Chemical Company) were used as received C -stilbene and perisobutyric acid (PIBAC) were prepared as described in [19], (-)-Caryophyllene (>99%) and eugenol (95%) were isolated from the oil of Eugenia caryopyllata by vacuum rectification. (+)-3-Carene (95%) and dipentene [( )-limonene, 95%] were prepared by rectification of the Pinus sylvestris turpentine. 

Terebene. A mixture of dipentene and other hydrocarbons obtained by shaking oil of turpentine with successive quantities of sulfuric acid Howard, Pharm. J. 103, 76 (1919). 

For thousands of years, turpentine has been obtained from conifers by a process known as tapping. A cut is made in the bark which prompts the tree to exude an oil which can be drained off into vessels attached to the tree. Turpentine thus obtained is referred to as gum turpentine. Nowadays, another form of turpentine is available in large quantities as a by-product of paper manufacture. When softwood (pine, fir, spruce) is converted into pulp in the Kraft paper process, the water insoluble liquids which were present in it are freed and can be removed by physical separation from the process water. This material is known as crude sulfate turpentine (CST). Fractional distillation of CST gives a number of products as shown in Table 9.2. (Dipentene is the name given to racemic limonene.) The residue from the distillation is known as tall oil and contains diterpenes such as abietic acid. 

Terpene tor- pen [ISV terp- (fir. Gr Terpen-tin turpentine, fir. ML terhentina) + -ene] (1873) n. A class of unsaturated organic compounds having the empirical formula C10H16 occurring in most essential oils and oleoresinous plants. Structurally, the unimportant terpenes and their derivatives are classified as monocyclic (dipentene), bicyclic (pinene), and acyclic (myrcene). 

Terpenes once commonly used are turpentine, dipentene and pine oil (p. 38). Turpentine varies with grade, but is principally a-pinene dipentene is mainly limonene while pine oils are mixtures, chiefly of terpene alcohols. Turpentine was once the main solvent for house paints, but has now been completely replaced by white spirit. Dipentene can be used as an anti-skinning agent (Chapter 10). 

Dipentene corresponds to a racemic mixture of D-limonene and L-limonene. Dipentene can be prepared from wood turpentine or by synthesis. It is used as a solvent for waxes, rosin and gums, in printing inks, perfumes, rubber compounds, paints, enamells, and lacquers. As an irritant and sensitizer, dipentene has caused contact dermatitis mainly in painters, polishers and varnishers. 

At that time, hydrocarbons occurring in essential oils with the molecular formula C,oH g were known, which had been named by Kekule terpenes because of their occurrence in turpentine oil. Constituents with the molecular formulas CigHigO and C,oH,gO were also known at that time under the generic name camphor and were obviously related to terpenes. The prototype of this group was camphor itself, which was known since antiquity. In 1891, Wallach characterized the terpenes pinene, camphene, limonene, dipentene, phellandrene, terpinolene, fenchene, and sylvestrene, which has later been recognized to be an artifact. 

As an essential oil, pine oil is also obtained by the steam distillation of needles, twigs, and cones from a variety of pine species (Figure 3B.2). Smaller amounts of limonene (dipentene) are industrially recovered as a by-product from the hydration of turpentine. Oil of Turpentine is a good solvent for many resins, waxes, fats, sulfur, phosphorus, and natural rubber. As a solvent for paints and varnishes, specifications, requirements, and test methods are standardized by DIN 53 248. Turpentine is used in traditional oil... 

These resins are generally grouped into three main categories depending on the source of the raw material (1,203,204). The indene-coumarone resins are coal tar based. Aliphatic, aromatic, and dicyclopentadiene resins are made from distillate fractions of cracked petroleum. Polyterpene resins are produced using monomers isolated from turpentine oil (a- or jS-pinene) or etheral oils of lemon, orange, mandarin, or caraway (d,Z-limonene or dipentene and d-limonene). 

Terebene, a mixture of dipentene and other hydrocarbons prepared from turpentine oil by treatment with concentrated sulphuric acid, is used chiefly in medicated soaps. Its specific gravity at 15° C. is 0 862-0 868 the oil is frequently slightly dextro- or Isevo-rotatory the refractive index at 20° 0., 1 470-1 478. ... 

---