Showing papers on "Terpene published in 1983"

Measurement and modeling of the concentrations of terpenes in coniferous forest air

Abstract: In a coniferous forest area northeast of Oslo, Norway, air samples were collected by adsorption on activated carbon and analyzed by gas chromatography with a high resolution glass capillary column and flame ionization detection. During June and August 1980, seven terpenes were identified with a total concentration range of 8.8–70.7 ppbC (parts per billion, as carbon). α-Pinene, terpinene, and p-cymene occurred in the highest concentrations. A one-dimensional vertical grid model of the atmospheric boundary layer with a detailed mechanism for inorganic and organic gas phase chemical turnover was applied to assess the vertical variability of the terpene concentrations as a function of the ozone concentration, the source strength of the terpenes, the time of the day, the upwind air composition, etc. The calculations showed that very little of the terpene emissions remained airborne after 4–8 hours, in contrast to the anthropogenic hydrocarbons. It was found that the anthropogenic fraction of the hydrocarbons may dominate in concentration, even though the natural part of the source is the larger one. Emission of 2000 μg(m2 h)−1 of terpenes was calculated to give ground level concentrations of total terpenes of up to about 25 ppbC, comparable to or less than the measured concentrations. Terpene emission at this rate was shown to suppress the hydroxyl concentration compared to a model case with zero terpene emissions, while the impact on ozone during daytime was negligible.

Two new m-cresol derivatives and a new terpene alcohol from peppermint oil.

Abstract: Two new m-cresol derivatives, 5-methyl-2-(2′-oxo-3′-butyl)-phenol (1) and 5-methyl-2-(3′-oxo-2′-pentyty-phenol (2), together with a terpene alcohol with a tetrahydrofuran structure, 3-(5′,5′-dimethyltetrahydrofuran-2′-yl)-cis-buten-1-ol (3), were isolated and identified in peppermint oil.

Chapter 13 Terpenoids

Abstract: Publisher Summary The terpenes constitute one of the largest and most structurally varied groups of natural products, and they exhibit a tremendous diversity in chromatographic properties, both within and between the various classes. This chapter focuses on the chromatography of relevant higher and lower isoprenalogs. The terpenoid vitamins (A, E, and K) have each been dealt with separately. Phosphorylated terpenes and glycosylated terpenes are described as these derivatives exhibit profound chromatographic differences relative to their parent terpenyl moieties. The chromatographic isolation of mevalonic acid (or mevalonolactone) is often required in the preparation of this isotopically labeled substrate for studies on isoprenoid biosynthesis, and, in the assay of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG CoA reductase), a key regulatory enzyme of the isoprenoid pathway. The enzyme assay generally involves the separation of the product, mevalonic acid (as the derived lactone), from the substrate, HMG CoA (often determined as HMG). Several simple thin layer chromatography (TLC) methods have been devised for this purpose, including chromatography on silica gel with acetone-benzene (1:1) and other developing solvents, or on Super-Cel–CaSO 4 (3:1) or cellulose.

A process for the conversion of terpenes

Abstract: There is disclosed a process for the conversion of terpenes to α-methyl-methylstyrenes and cymenes which comprises contacting at least one terpene, selected from the group comprised of mono- and bi-cyclic unsaturated hydrocarbons having the formula C 10 H 16 ; with an alkali metal hydroxide catalyst on a support at a temperature of 300 to 500°C.