Terpenes, separation

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... 

Strategy Problem 6 A labelled compound for biosynthetic studies. Mevaloitic acid (TM 418) is an intermediate in the biosynthesis of terpenes and steroids (Tedder, volume 4, p.217 ff). To study exactly what happens to each carbon atom during its transformation into, say, hmonene (418A), we need separate samples of mevalonic acid labelled with in each carbon atom in the molecule. This turns our normal strategy on its head since we must now look for one carbon discoimections. You can use reagents like Na CN, and... 

Chemical iajections iato piae trees have been reported to have stimulatory effects on the natural production of resias and terpenes and may result ia high yields of these valuable chemicals. Combiaed oleoresin—timber production ia mixed stands of piae and timber trees is under development, and it appears that when short-rotation forestry is used, the yields of energy products and timber can be substantially higher than the yields from separate operations. 

Aroma Distillate. Used by the flavor industry, aroma distillates are the product of continuous extraction of the plant material with alcohol at temperatures between ambient and 50°C followed by steam distillation, and, lastly, concentration of the combined hydro—alcohoHc mixture. On cooling, terpenes often separate from the aroma distillate and are removed. 

Fractional vacuum distillation is the method used to separate terpene mixtures into their components. The terpene chemist usually has in the laboratory a range of columns with differing numbers of theoretical stages. Experimental distillation in the laboratory is useful in providing data for manufacturing plants that produce commercial quantities of terpene products. 

Since the acetal exists in equiUbtium with the aldehyde, it is possible for the aldehyde to be released when water is added in a mixed drink, changing the balance and giving a burst of freshness to a mixed drink. Ethyl esters of terpene alcohols in citms oils and other botanicals, plus the ethyl esters of fatty and volatile acids, are formed during prolonged exposure to ethyl alcohol. Certain beverage alcohol products that need to contain milk, eggs, or other protein containing materials must be developed carefully and the added flavors must be considered to prevent the precipitation of the protein and separation of the product. 

Essential Oils. Volatile oils from plants are referred to as essential oils. The oils can be obtained through steam distillation, solvent extraction, or separation of the oils from pressed fmit. They consist of oxygenated compounds, terpenes, and sesquiterpenes. The primary flavor components of essential oils are oxygenated compounds. Terpenes contain some flavors but are often removed from the essential oil because they are easily oxidized (causiag off-flavors or odors) and are iasoluble. Essential oils are prepared from fmits, herbs, roots, and spices. 

Trees, especially conifers, contain tall oils. Tall oil is not isolated dkecfly tall oil fatty acids are isolated from the soaps generated as a by-product of the sulfate pulping process for making paper. Refined tall oil fatty acids are obtained by acidification of the soaps, followed by fractional distillation to separate the fatty acids from the rosin acids and terpene hydrocarbons that also are present in the cmde tall oil fatty acids (see Carboxylic acids Fatty ACIDS FROMTALL OIL). 

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. 

It is the determination of volatile organic compounds produced from natural products that requires separation techniques that allow isolation of stereoisomers. The most commonly determined groups are the terpene and sesquiterpene species present in essential oils, which are used as key indicators of biological factors such as the growth season, geographic location, climate, etc. These species are also released directly into the atmosphere by very many plants and trees, and make a substantial contribution to global biogeochemical cycles. 

Most essential oils appear to be evolved directly in the form of terpenic or non-terpenic compounds separable from the plant tissues in the same form as they exist therein. A considerable number, however, are evolved in the form of complex compounds known as glucosides, in which the essential oil complex is present, but wherein the essential oil itself does not exist in the free state. 

The identification of camphene is best carried out by its conversion into isobomeol under the influence of acetic acid in the presence of sulphuric acid. In order to effect this conversion, 100 grams of the fraction containing the terpene in substantial quantity are mixed with 250 grains of glacial acetic acid and 10 grams of 50 per cent, sulphuric acid. Tne mixture is heated for two to three hours on a water-bath to a temperature of 50° to 60°. At first the liquid separates into two layers, bat soon becomes homogeneous and takes on a pale red colour. Excess of water is added, and the oil which is precipitated, and which contains the isobomeol in the form of its acetate, is well washed with water repeatedly. It is then saponified by heating with alcoholic potash solution on a water-bath. The liquid is then evaporated and extracted with water, and the residue recrystallised from petroleum ether. 

Up to this point no evidence was forthcoming that any oneoffthe fenchenes prepared was pure, as the optical rotation of nearly every specimen was different. Wallach i has, however, more recently prepared fenchene by treating fenchyl-amine with nitrous acid. The resulting terpenes were separated by fractional distillation into two main portions, one of which had the following characters —... 

By systematic fractionation of a large quantity of sabinene obtained from oil of savin, Schimmel Co. separated the crude terpene into the following fractions —... 

Both limonenes yield nitrosochlorides, Cj Hj NOCl, each of which can be separated into two modifications. There are thus four limonene nitrosochlorides they are known as the a- and /3- varieties of the dextro-and Zdew-rotatory forms of the terpenes. The a- and /3- forms, however, yield the same carvoxime on treatment with alcoholic potash. 

Five parts of the terpene, 7 of amyl nitrite, and 12 of glacial acetic acid are mixed and cooled with ice and salt, and a mixture of 6 parts of hydrochloric acid and 6 parts of glacial acetic acid added in small quantities at a time. Five parts of alcohol are then added and the mixture allowed to stand in a freezing mixture for a itime. A mass of crystals separates, which consists of the crude nitrosochlorides. This is filtered off and washed with alcohol. When perfectly dry 100 grams of the crystals are digested with 200 c.c. of chloroform for a few moments and at once filtered. The chloroform dissolves a-nitrosochloride, which is precipitated by the addition of excess of methyl alcohol. The crude compound is filtered off, dried and digested with anhydrous ether for... 

There appear to exist two very closely allied terpenes, which have so similar constitutions and characters that it is almost impossible, if not quite so, to separate them when existing together naturally. The synthetically prepared sylvestrene is, of course a distinct individual, the constitution of which will be dealt with directly. 

Sylvestrene nitrosochloride, CjoHj,. NOCl, is prepared from pure sylvestrene, regenerated from the dihydrochloride in the following manner Four volumes of the terpene are dissolved in six of amyl nitrite and five volumes of strong hydrochloric acid are added, with constant shaking. The heavy oil which separates is shaken with a little ethyl alcohol, when it solidifies, and can be purified by dissolving it in chloroform and precipitating it with petroleum ether. It is finally recrystallised from methyl alcohol, when it melts at 106° to 107°. 

Principal ingredient of eucalyptus oils, isolated after separation of remaining terpenes with sulfuric acid. Reference(s) ... 

Longifolene is a tricyclic sesquiterpene. It is a typical terpene hydrocarbon in terms of the structural complexity. The synthetic challenge lies in construction of the bicyclic ring system. Schemes 13.24 through 13.33 describe nine separate syntheses of longifolene. We wish to particularly emphasize the methods for carbon-carbon bond formation used in these syntheses. There are four stereogenic centers in longifolene,... 

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