Limit Limonene

Health and Safety. FEMA has examined cinnamaldehyde and estabhshed its GRAS status (No. 2286). The material has been used in some fragrance compositions, but RJEM (34) has noted its potential for sensiti2ation and limited the use in perfumes for skin contact at 1% in the formula. Eugenol and limonene have been used in conjunction with cinnamaldehyde as quenchers to neutrali2e the irritation reaction that some individuals have toward this aldehyde. 

D-limonene (Florida Chemicals). A compound of optically active terpene (CioHie) derived as an extract from orange and lemon oils limited data shows veiy low viscosity at low temperatures—only one centipoise at —50°C natural substance having questionable stabihty, Theiminol D-12 (Mon.santo). A synthetic hydrocarbon clear liquid ... 

Figure 10.4 Temperature profiles for three classes of analytes monoterpenes (limonene) sesquiterpenes [(3 caryophyllene, caryophyllene oxide (caryo. oxide)] and diterpenes [cem brene A, isoincensole acetate (iso. acetate)]. PDMS fibre, sampling time 40 min. Reproduced from S. Hamm, E. Lesellier, J. Bleton, A. Tchapla, J. Chromatogr., A, 1018, 73 83. Copyright 2003 Elsevier Limited...

Selenium dioxide is also an oxygen donor to alkenes. In this case, however, the initial reaction of the double bond is with the selenium center followed by two pericyclic steps. After hydrolysis of the organo-selenium intermediate, the result is a hydroxylation at the allylic carbon position65. Thus, limonene (2) yields racemic p-mentha-l,8(9)-dien-4-ol66. The high toxicity of selenium intermediates and prevalence of many rearrangements has limited the widespread use of the reagent in synthesis. 

Limonene and perillic acid remarkably reduced the lung metatastatic tumour nodule formation by 65 and 67%, respectively however, perillyl alcohol was considerably more potent than limonene against breast cancer [284, 302], rat mammary cancer and pancreatic tumours [288]. Phase 1 studies of d-limo-nene [303, 304] and phase I and phase II [305-311] studies of perillyl alcohol revealed dose-limiting toxicities nausea, vomiting, anorexia, unpleasant taste and eructation, and thus a maximum tolerated dose for perillyl alcohol was determined [305]. 

A time-weighted average (TWA) or other occupational exposure limit is unavailable for D-limonene. The Workplace Environmental Exposure Level (WEEL) for limonene (terpenes) is 30 ppm as an 8 h TWA. 

Lee et al. reported on the prevalence of pulmonary and upper respiratory tract symptoms experienced by pressmen exposed to low levels of aliphatic hydrocarbons, limonene, glycol ethers, isopropyl alcohol, and mineral oil. The airborne levels of these solvents were below the permissible exposure limits. 23 No explanation was offered to account for the observed results. 

Composition According to ISO [19], the oil contains 86-95% E-anethole, up to 1.0% Z-anethole and up to 6.0% methyl chavicol. Eoeniculin can occur up to 3.0%, anisic aldehyde is limited to 0.5%. Further constituents are monoterpenes like a-pinene, a-phellandrene, limonene, linalool and a-terpineol. Besides P-caryophyllene, two further sesquiterpenes are typical trace components for Chinese star anise oil, namely E-and Z-a-bergamotene. 

Composition 30-55% (-)-menthol, 14-32% (-)-menthone, 1.5-10% (-i-)-iso menthone, 2.8-10% menthyl acetate, 3.5-14% 1,8-cineole, 1-9% menthofuran, up to 4% pule-gone [220], as well as 3-octanol, trans-sabinene hydrate, piperitone, viridrflorol, mono- and sesquiterpene hydrocarbons. For further constituents see [221, 222, 223[. On the differentiation between peppermint oils and the detection of dementholised commint oil as a major adulterant see the results of Lawrence et al. [224], The ratio of 1,8-cineole limonene (min. 2) was even implemented in the European Pharmacopoeia. The latter also limits the isopulegol content for Mentha piperita oil to 0.2%. 

D-Limonene Another class of low-temperature HTF is based on naturally derived terpenes such as D-limonene. U.S. Patent 3,597,355 describes o-limo-nene as being particularly preferred among all the monocycloterpenes because of its characteristic properties such as low viscosity at low temperatures. D-Limonene is the major component in the oil of citrus fruit and is present in trace quantities in orange juice. It is recovered in commercial quantities by distilling orange oil obtained from citrus peels. Being derived from the citrus industry, o-limonene is considered a safe and environmentally friendly HTF, and hence it is preferred in many food and pharmaceutical processes. However, the melting point of D-limonene is about —78°C. Below this temperature, it becomes a thick white gel like substance that is impossible to pump. Therefore, the use of o-limonene is limited to... 

---