beta-Pinene

Description

Beta-pinene is a component of turpentine. Concentrations vary depending on the source and seem to be high er in European (Portuguese) than in Asian (Indonesian) turpentines.

Description

β-Pinene, a bicyclic monoterpene, is the second-most abundant constituent of the resins produced by pine trees and other conifers. The most abundant is its isomer α-pinene1, the Molecule of the Week for May 14, 2012. Both pinenes exist in nature as their (+)- and (–)-enantiomers. The images show the (+)-enantiomer of β-pinene.
The pinenes are the chief ingredients of turpentine2, a solvent that was in widespread use as a diluent and cleaner when oil-based paints were in their heyday. It is also used in varnishes and as a raw material for synthesizing useful organic compounds.
Turpentine was mentioned in the chemical literature as early as 1875 in US Patent 162,394, in which Archibald K. Lee of Galveston, TX, used it in an improved process to dissolve “asphaltum”, a soluble form of asphalt. In 1893, Walter E. Rohner of New York City was awarded US 498,961 for its use in a “wood-polishing compound”.
β-Pinene itself was first identified in 1896 by noted German chemist Adolf von Baeyer in an extensive paper on the origins of terpenes. Baeyer, who also developed syntheses of indigo, phenolphthalein, and fluorescein, was awarded the 1905 Nobel Prize in Chemistry.
Much more information about β-pinene can be found in ScienceDirect’s information page on the molecule.
1. CAS Reg. No. 80-56-8. 2. CAS Reg. No. 9005-90-7.

Chemical properties

liquid

Chemical properties

β-Pinene occurs in many essential oils. Optically active and racemic β-pinenes are present in turpentine oils, although in smaller quantities than αα-pinene. (+)-β-Pinene, (1R,5R)-6,6-dimethyl-2-methylenebicyclo(3.1.1)heptane,; (?)-β-Pinene, (1S,5S)-6,6-dimethyl-2-methylenebicyclo(3.1.1)heptane,. β-Pinene is similar to α-pinene in its reactions. Pyrolytic cleavage to myrcene, the startingmaterial for acyclic terpenes, is used on an industrial scale.Addition of formaldehyde results in the formation of nopol; nopyl acetate is used as a fragrance material. β-Pinene is produced in large quantities by distillation of turpentine oils. It is used as a fragrance material in household perfumery.However,most β-pinene is used in the production of myrcene.

Chemical properties

β-Pinene has a characteristic turpentine odor with a dry, woody or resinous aroma.

Occurrence

Usually occurring together with α-pinene but in smaller amounts; the d- and l-forms are reported found in the essential oils of various Artemisae and several Cupressaceae, in coriander and cumin; the l-form is a constituent of several citrus oils. β-Pinene is reported found in over 190 natural products including apple, apricot, many citrus juices and peel oils, bilberry, cranberry, lingonberry, blackberry, currants, guava, raspberry, strawberry, basil, carrot, celery, cooked potato, bell pepper, tomato, anise seed oil, cinnamon, cassia leaf, clove, cumin, ginger, Mentha oils, nutmeg, mace, pepper, parsley, thyme, Swiss and cheddar cheese, cream, fatty fish, fried chicken, beef fat, hop oil, rum, bourbon whiskey, tea, roasted filberts, pecans, oats, soybean, plum, mushroom, sweet and wild marjoram, starfruit, mango, tamarind, cardamom, coriander, gin, rice, litchi, calamus, dill, lovage, caraway seed, buckwheat, laurel, fennel, kiwifruit, myrtle leaf and berry, rosemary, buchu oil, Bourbon vanilla, Spanish and clary sage, nectarine, crayfish, clam, cape gooseberry, anise hyssop, angelica root oil, Roman and German chamomile oil, eucalyptus oil, bullock’s heart and mastic gum leaf and fruit oil.

Definition

ChEBI: An isomer of pinene with an exocyclic double bond. It is a component of essential oils from many plants.

Preparation

Isolated from American turpentine; also by conversion from α-pinene; as an intermediate extremely important for the manufacture of citral, citronellol, hydroxycitronellal, geraniol, citronellal, linalool, ionones, methylionones and menthol.

Aroma threshold values

Detection: 140 ppb. Aroma characteristics at 10%: cooling, woody, piney and turpentine-like with a fresh minty, eucalyptus and camphoraceous note with a spicy peppery and nutmeg nuance.

Taste threshold values

Taste characteristics at 15 to 100 ppm: fresh, piney and woody, terpy and resinous with a slight minty, spicy and camphoraceous nuance.

Contact allergens

Beta-pinene is a component of turpentine. Concentrations vary with the source and seem higher in European (Portuguese) than in Asian (Indonesian) turpentine.

Safety Profile

Mddly toxic by ingestion. A skin irritant. Flammable liquid. When heated to decomposition it emits acrid smoke and irritating fumes.