Semi-synthetic oils

Semi-synthetic oils are obtained from mixing both types of bases (generally 70 to 80% of mineral oil and 20 to 30% of synthetic oil). 

Semi-synthetic oils contain mineral oils of concentrations varying between io% and 50%. They therefore provide more lubrication than synthetic oils. To enable the mineral oil to blend with water and remain in a finely dispersed state requires the addition of emulsifiers (20-40%). These are often based on petroleum sulphonates, which are produced by the sulphuric-acid treatment of spindle oils to produce white oils and carboxylic acids. 

Synthetic and semi-synthetic oils have been developed from blends of chemicals that are more man-made than natural. They are considered to be high performance products with the ability to meet performance standards and have controllable, stable flow characteristics. They attempt to achieve a careful balance between the... 

Epidemiological studies relevant to the evaluation of di- and triethanolamine and jV-nitrosodiethanolamine involve occupational cohorts exposed to metalworking fluids. Metalworking fluids can be divided into four broad categories straight oils, soluble oils, semi-synthetic and synthetic fluids. 

Semi-synthetic fluids contain smaller amounts of oil than soluble oils (3-30%), along with the same mixture of additives mentioned below for synthetic fluids. They are typically diluted 1 10 to 1 40 for use. This category has not been examined separately in epidemiological studies. One study (Sitllivan et al., 1998) grouped semisynthetic oil exposure with soluble oil exposures. 

Some more modern semi-synthetic metal-working oils are actually O/W microemulsions [193], Such microemulsions may switch readily to O/W macroemulsions when diluted with water at the time of application. Once applied, the surfactants need to adsorb onto metal surfaces with their hydrophobic groups oriented away from the surfaces in order to reduce friction and ensure wetting of the metal by hydrocarbons present in the metal-working liquid or emulsion. Rosen and Daha-nayake [193] list the commonly used surfactants for this application. 

The oils from nutmeg, dill, parsley seed, calamus, crocus, saffron, vanilla beans, sassafras and other plants contain generous amounts of the precursors to the semi-synthetic MDA-like compounds. Recently dried nutmeg is about 15 percent extractable oil. 

MDA, MMDA and the other semi-synthetics are prepared by aminiza-tion of various natural oils, which seems to eliminate nearly all the unpleasant physical effects of the experience for most people. 

A useful synthesis (ref.ll)of patchouli alcohol, an important fragrant constituent of patchouli oil, from (+)-camphor, that onetime important natural product which was employed as a plasticiser for nitrocellulose (itself a semi-synthetic polymer), was complicated by structural revision of the sesquiterpene alcohol. Dihydrocarvone (14) obtained by saturation of the ring double bond in carvone, a major constituent of oil of spearmint has been employed for two very different sesquiterpenes, the ketone campherenone (15) and the alcohol, occidentalol (16). In the first case an enol acetate was converted to a bicyclic intermediate by earlier established methodology and the route emulated a plausible biogenetic sequence giving racemic campherenone (ref.12) as shown. Any chirality in (14) is apparently lost. 

Semi-synthetic meal composed of dextrimaltose, corn oil and ovalbumin. 

The three main groups of compressor lubricants are for (i) gases, (ii) refrigerators and (iii) vacuum pumps. Depending on the application, various classes of lubricating oils are used, including mineral oils of various levels of refinement, semi-synthetic and/or synthetic oils. Some lubricants for gas compressors may contain a wide variety of additives. 

About one tenth of the total amount of vitamin E produced is semi-synthetic, isomerically pure (2R,4 K,8 R)-a-tocopherol (RRR-3) which is used almost exclusively in human applications (mainly pharma). This product, originating from natural sources, is obtained from soya deodorizer distillates (SDD). Vegetable oils refined on a large scale are the major sources of vitamin E compounds [26-28]. The deodorizer distillate, originally a waste stream, contains considerable amounts (up to 10%) of a-, [I-, y- and b-tocopherols (RRR-3 to RRR-6) which are isolated by several separation methods. To increase the value of the vitamin E concentrate of mixed tocopherols obtained from SDD, the lower (I-, y- and d-homologues (RRR-4 to RRR-6, content ca. 90%) have to be transformed subsequently into the biologically more active a-tocopherol (RRR-3, only ca. 5% in the original mixture) by permethylation reactions. Permethylations are performed by chloro-, amino-, or hydroxymethylation reactions to provide functionalized alkylated intermediates, which are reductively converted into RRR-3 (Fig. 3) [29]. 

The range of motor oils providing superior performance in passenger car engines. The range includes fully synthetic, semi-synthetic and mineral oils for different types of engines, age and operation. 

The application of semi-synthetic (R,R,R)-a-tocopherol from natural sources is exclusively restricted to the pharmaceutical, food, and cosmetic industry. The most important natural sources of vitamin E are plant oil and fats. Various processes... 

A number of alkenyiphenols of natural origin are of great importance in the perfume and flavour industries, such as eugenol (1), the principal component of oil of cloves, its semi-synthetic isomerisation product iso-eugenol (2), the phenolic ether, anethole (3) from fennel and oil of aniseed (umbelliferacae), and also of semisynthetic origin from chavicol (4). Their chemistry is not included in the present account which is devoted to less well-known substances. 

The reaction of phenol with natural C q (and C.,5) acyclic hydrocarbons such as the readily available myrcene, ocimene or alloocimene from the replenishable source pine oil, does not seem to have been examined in detail although the semi-synthetic 4- and 2-alkenylphenolic products obtained from it could be... 

Perillartine is the semi-synthetic a-,s> r/-oxime of perillaldehyde, a major constituent of the volatile oil of Perilla frutescens (L.) Britton (Labiatae), and is used in Japan as a replacement for maple syrup or licorice in the sweetening of tobacco (33). Neohesperidin dihydrochalcone, prepared by the sequential alkaline hydrolysis and catalytic reduction of neohesperidin, a flavanone constituent of Citrus aurantium L. (Rutaceae), is permitted for use In chewing gum and certain beverages in Belgium and elsewhere (31). 

The resins used for the manufacture of food and beverage can lacquers may be either natural or synthetic. Resins combined with drying or semi-drying oils form a class of coatings known as oleoresinous. Other coatings for food and beverage cans are obtained using synthetic resins such as phenolics and epoxies, and acrylic, vinyl, and butadiene polymers. For a brief summary as to what type of resins are used for cans, see Table I. 

---