Fi-Pinene

Figure 2.8 a- and fi-pinene obtained as by-products from the pulping of wood. 

A variety of alkenes undergo successful amidomercuration, but alkenes of the type R2C CH2 and R2C=CHR fail to react in the anticipated fashion.243-245 While rearrangements have been observed with a- and fi-pinene,243 3,3-dimethyl-1 -butene reacts normally.244... 

Main components Linalyl acetate, linalool, limonene, fi-pinene, y-terpinene. Additives (e.g. carriers, preservatives, antioxidants) NIL Bergaptene less than 20 ppm. 

Kennedy, J. P. and Chou, T. Poly(isobiitylene-co-fi-Pinene) A New Sulfur Vulcanizable, Ozone Resistant Elastomer by-Cationic Isomerization Copolymerization. Vol. 21, pp. 1-39. 

In an analogous way, rac-fi-pinene (18) is transformed into 6.6-dimelhyl-2-methylenebicy-clo[3.1, l]heptan-3-ol [(-)-pinocarveol, 19], 6,6-dimethyl-2-methylenebicyclo[3.1.1]heptan-3-one [(-)-pinocarvone, 20], 6.6-dimethylbicyc o[3.1.1]hept-2-ene-2-methanol [( )-myrtenol. 21]338. 

U. Hener, P. Kreis and A. Mosandl. Enantiomer distribution of a-pinene, fi-pinene and limonene in essential oils and extracts Part 3 oils for alcoholic beverages and seasoning. Flav. Fragr. J., 109-111 (1991). 

Methyl-6-methylen-octen-(2) (II) geht bei der mit Benzophenon, Fluorenon oder 2-Acetyl-naphthalin sensibilisierten Reaktion in das 5,5-Dimethyl-l-vinyl-bicyclo[2.1.1] hexan (III 75 % d.Th.) iiber1. Bei direkter Belichtung in Afcher entstehen nur 3% dieses Produkts und dafiir das 6,6-Dimethyl-2-methylen-bicyclo[3.1.1]heplan (IV fi-Pinen 14-16% d.Th.) und l-l4-Methyl-penten-[3)-yl]-cyclobuten (V 81-83% d.Th.)2 ... 

Synthesis from fi-Pinene. Pyrolysis of / -pinene yields myrcene, which is converted into a mixture of predominantly geranyl, neryl, and linalyl chloride by addition of hydrogen chloride in the presence of small amounts of catalyst, e.g., copper(I) chloride and an organic quaternary ammonium salt [29]. After removal of the catalyst, the mixture is reacted with sodium acetate in the presence of a nitrogen base (e.g., triethylamine) and converted to geranyl acetate, neryl acetate, and a small amount of linalyl acetate [30]. 

Synthesis from fi-Pinene. For a description of this route, see under geraniol. Addition of hydrogen chloride to myrcene (obtained from / -pinene) results in a mixture of geranyl, neryl, and linalyl chlorides. Reaction of this mixture with acetic acid-sodium acetate in the presence of copper(I) chloride gives linalyl acetate in 75-80% yield [37]. Linalool is obtained after saponification. 

Hydroformylation of a- and fi-pinene in the presence of [Rh(SR2)(CO)L]2 complexes [L = PPh3, P(OPh)3, or P(OC H3)3] is rather slow, giving low conversions40. Depending on the reaction times both isomers give mixtures of the expected isomeric aldehydes with partial isomerization of the double bond. No detailed information about the stereochemical course of these conversions is available40. 

Since 0-pinene readily isomerizes to a-pinene and other products in acidic media (20), it was important to examine the possibility of isomerization under our polymerization conditions. Thus a polymerization experiment has been carried out under conditions conducive for isomerization ([M] = 3.5M, [EtAKlj ] = 10-3 M, —70°, for 30 minutes). Conversion was about 6%. After quenching with methanol and workup as described in Section B, the liquid charge was extracted with water (to remove methanol) and subsequently with n-pentane. The composition of the extract was analyzed by G.C. and compared with an original 0-pinene sample. According to gas chromatographic analysis, fi-pinene did not isomerize and the composition of the liquid charge was virtually identical before and after polymerization e.g., 98% /3-pi-nene, 0.9% a-pinene and 1.1% unidentified compounds. 

Ring expansion of a- and fi-pinene. When either a- or jS-pinene, (1) or (2), is heated neat with an initial pressure of 30 psi CO at 160° for 68 hr. with an equimolar amount of iron pentacarbonyl, two ketones, (3) and (4), are obtained, formed by insertion of CO into the cyclobutane ring together with some a-pinene. Both ketones are optically active. The Cotton effects are of nearly the same... 

Composition Pressed L. has a very similar composition to that of lemon oil. Main components are limonene (ca. 50%), fi- pinenes (ca. 10-20%), and Y-terpinene (ca. 10%). The component responsible for the typical odor and taste is citral (3-5%). 

TABLE 10.1. Comparison of Chromatographic Processes for Separation of a and fi Pinenes... 

Essential oils from Pinus halepensis, Pinus brutia, Pinus pinaster, Pinus pinea, and Cedrus atlantica were tested for molluscicidal activity against Bulinus truncatus. The oil from C. atlantica was found the most active (LC 50 = 0.47 ppm). Among their main constituents, a-pinene, fi pinene. 

Figure 22.7 Observed and calculated VCD spectra of (S)-fi-pinene. (a) Observed spectrum, (b)-(e) calculated spectra. Methods of calculation are (b) B3LYP/6-31+C, (c) B3LYP/6-31, (d) HF/6-32+C, (e) HF/4-31C.

A number of linear polymers are soluble in organic solvents that are able to be eliminated rapidly (through evaporation) after the adhesive has been deposited. This is the case, for example, for poly(fi-pinene) (O Fig. 14.5) which, dissolved in methyl ethyl ketone, has for a long time been the basis of universal glues Scotch by 3M). 

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