Terpene, wood

Terpene-based hydrocarbon resins are typically based on natural products such as a-pinene, P-pinene, and ti-limonene [5989-27-5] which are obtained from the wood and citms industries, respectively. These resins, which were originally the preferred tackifiers for natural mbber appHcations, possess similar properties to aHphatic petroleum resins, which were developed later. Terpene-based resins have been available since the mid-1930s and are primarily used in the adhesives industry. 

Pine Oil. This oil is obtained by extraction and fractionation or by steam distillation of the wood of Pinuspalustris Mill, and other species. Most of the oil is produced ia the southeastern United States. The composition of the oil depends on the fractions chosen, but the chief constituents are terpene alcohols, mainly terpiaeol. Piae oil finds use as a germicide ia disiafectants and soaps as an ingredient ia iasecticides, deodorants, poHshes, sweepiag compounds, and catde sprays and as raw material for the manufacture of perfumery-grade terpiaeol [8000-41 -7], anethole [104-46-1], fenchone (137), and camphor (35). 

Wood also contains 3—10% of extraceUulat, low molecular weight constituents, many of which can be extracted from the wood using neutral solvents and therefore ate commonly caUed extractives. These include the food reserves, the fats and their esters in parenchyma ceUs, the terpenes and resin acids in epitheUal ceUs and resin ducts, and phenoUc materials in the heartwood. Resin materials occur in the vessels of some hardwood heartwood. 

By-Products. There are three stages within the pulping operation at which wood-derived chemicals can be recovered as by-products. Turpentine is obtained from the reHef of gases after an initial steaming of chips in the digester. Better yields of turpentine are obtained from batch digesters than from continuous systems. Pines and firs give the best yields. Turpentine is composed principally of unsaturated bicycHc hydrocarbons, of which ca 90% are a- and P-pinenes and 5—12% other terpenes. 

The other class of acrylic compatible tackifiers includes those based on ter-penes. Terpenes are monomers obtained by wood extraction or directly from pine tree sap. To make the polyterpene tackifiers, the monomers have to be polymerized under cationic conditions, typically with Lewis acid catalysis. To adjust properties such as solubility parameter and softening point, other materials such as styrene, phenol, limonene (derived from citrus peels), and others may be copolymerized with the terpenes. 

Gum turpentine is obtained from wounding living trees to get an exudate containing turpentine and rosin. Turpentine is separated from the rosin by continuous steam distillation and further fractionation. Wood turpentine comes from the extraction of stumps of pine trees using naphtha, and subsequent separation of rosin and turpentine by fractional distillation. Tail-oil turpentine is a byproduct of the Kraft sulphate paper manufacture. Terpenes are isolated from the sulphate terpentine and separated from the black digestion liquor. The composition of turpentine oils depends on its source, although a-pinene and p-pinene are the major components. 

Odour. This aspect is important in resins derived from natural sources. Rosins based on wood and gum rosin retain trace quantities of terpenes and have a piney odour. Tall oil rosins retain the typical sour odour of the rosin. Odour can be removed by steam sparging under vacuum before or during esterification of rosins. Addition of odour masks can also be done. 

Polyterpenes. Polyterpenes is one of the first classes of non-polar tack-ifiers to be developed. Terpene monomers are a by-product in the extraction of rosin from wood stumps or tree sap, and from the extraction of oils from citrus fruits. The latter is the dominant source. As such, polyterpene prices generally mirror those of citrus fruits, which fluctuate substantially from one growing season to the next. Terpenes like rosin are cyclic, see Fig. 6, which is partly responsible for their excellent solvent properties. 

Emission of volatile noxious chemicals from wood-based panels during their production can be caused by chemicals inherent to wood itself, like terpenes or free acids, as well as by volatile compounds and residual monomers of the adhesive. The emission of formaldehyde as well as free phenol effluents is a matter of concern. 

The use of nitrogen fertilization results in higher content of N-containing compounds, including free amino acids, and also increases in terpene content in wood plants, whilst starch, total carbohydrates, phenylpropanoids and total carbon-based phytochemicals decreased (Koricheva et al., 1998). Higher levels of nitrogen favoured its uptake and increased the nitrate content of the crop, which is critical for salad vegetables and baby foods. 

Wood contains a small proportion (usually less than 5%) of components which are extractable by organic solvents such as ethanol or dichloromethane. The proportion of these extractives varies in hardwoods and softwoods and also between species. Although many of these substances are removed during the chemical pulping process, some may still be retained in the final sheet of paper. Their chemical composition is very varied, and they include alkanes, fatty alcohols and acids (both saturated and unsaturated), glycerol esters, waxes, resin acids, terpene and phenolic components. The proportion which remains in pulp and paper depends upon the pulping process used. In general, acidic components such as the resin and fatty acids are relatively easily removed by alkali by conversion to their soluble... 

ThermoWood is not resistant to exterior weathering and the colour will gradually change to the grey that is characteristic of outdoor exposed wood. In addition, exposure in exterior conditions results in the formation of small cracks on the surface of uncoated wood. Unpigmented or low-build stain coatings do not protect the surface of the wood, but solvent-borne alkyds and water-borne acrylic paints have been found to exhibit better performance than on unmodified wood. VOC emissions from the heat-treated wood are lower compared to unmodified wood and the compositions of the emissions differ. The level of emissions is lower when the wood is treated at a higher temperature. Emissions of terpenes are reduced to very low levels, and the VOC content is dominated by furfural, hexanal and acetic acid (treated at 180 °C), and by acetic acid (treated at 230 °C). ThermoWood passes ecotoxicity tests. 

Staccioli G, Mellerio G, Alberti MB, Investigation on terpene-related hydrocarbons from a Pliocenic fossil wood, Holzforschung 47 339—342, 1993. 

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... 

Balsam turpentine oil is obtained from the resins of living trees of suitable Pinus species by distillation at atmospheric pressure and temperatures up to 180°C, or by other fractionation methods, which do not change the terpene composition of the resins. Wood turpentine oils, on the other hand, are generally obtained by steam distillation of chopped tree trunks, dead wood, or of resin extracted from this wood. Sulfate turpentine oil is produced as waste in the manufacture of cellulose by the sulfate process and is also a wood turpentine. Pine oil is another wood turpentine oil that is obtained by dry distillation of suitable pine and fir trees, followed by fractionation. However, the term pine oil is nowadays used for a product which is manufactured by hydration of turpentine oil (a-pinene). The resulting product is a mixture of monoterpenes containing o-terpineol as the main component. In addition to many other technical purposes, it is used to a large extent in cheap perfumes for technical applications. 

The most important and frequently used terpene esters in flavours are the acetates of nerol, geraniol, citronellol, linalool and isoborneol [12], As discussed before, all these terpene alcohols are available both from renewable resources and from petrochemical origin. Acetic acid can be obtained from renewable resources by pyrolysis of wood as wood vinegar, and also by synthesis from petrochemical origin. 

Bone charcoal or activated wood charcoal is a convenient accelerator, combination occurring instantly. If the vessel in which the reaction is carried out is cooled to 30° C., the sulphuryl chloride is condensed and may be drained away as rapidly as it is formed.8 The terpene... 

Turpentine oils extracted from pine resins are now marginal sources of terpenes pinenes, carene and some other monoterpenes are essentially obtained from the paper oils produced in the KRAFT process. Nevertheless this process is based on a treatment of wood chips in sodium sulfide, which leaves significant fractions of sulfur compounds in the paper oils. For the use of terpenes, these sulfur compounds must be eliminated. The process requires ... 

The odor of a freshly crushed mint leaf, like many plant odors, is due to the presence in the plant of volatile C10 and Ci5 compounds, which are called terpenes. Isolation of these substances from the various parts of plants, even from the wood in some cases, by steam distillation or ether extraction gives what are known as essential oils. These are widely used in perfumery, as food flavorings and medicines, and as solvents. Among the typical essential oils are those obtained from cloves, roses, lavender, citronella, eucalyptus, peppermint, camphor, sandalwood, cedar, and turpentine. Such substances are of interest to us here because, as was pointed out by Wallach in 1887 and reemphasized by Ruzicka in 1935, the components of the essential oils can be regarded as derived from isoprene ... 

The odor of wood is mostly caused by the terpenes contained in the resin. Differences in the composition of several kinds of resin have been investigated (Moyler and Clery, 1997). There is also some data available on the emissions of treated wood, wood products and furniture (Baumann, Batterman and Zhang, 1999 Risholm-Sundmann et al., 1998 Salthammer, 1999a Salthammer, Schwarz and Fuhrmann, 1999). Besides terpenes like a-pinene, P-pinene, A3-carene, longi-folene, P-phellandrene, camphene, myrcene, carvone, limonene, caryophyllene,... 

Bedard W. D., Tilden P. E., Wood D. L., Silverstein R. M., Brownlee R. G. and Rodin J. O. (1969) Western pine beetle field response to its sex pheromone and a synergistic host terpene, myrcene. Science 164, 1284-1285. 

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