Artificial preparation

Camphene is extremely difficult to separate in the solid condition from essential oils, and it may therefore be taken for granted that natural camphene is rarely prepared in the pure condition. The figure given above for the specific rotation is for a sample artificially prepared from pinene hydrochloride. 

A terpene yielding isofenchyl alcohol on hydration, which Wallach considers to be one of the fenchenes, was artificially prepared by converting nopinone into a hydroxy ester by means of bromoacetic ester and zinc-dust. The hydroxy ester is dehydrated by potassium bisulphate, and so yields an unsaturated ester, which on saponification yields an acid from which the terpene results by distillation. This fenchene has the following characters —... 

The above-described compound is known as terpinenol-4 in accordance with recognised nomenclature. A body known as terpinenol-1 is present to a small extent in the artificially prepared commercial terpinenol. This body has the following characters —... 

Methyl Malonate.—This ester is an artificially prepared body, having a fruity odour, somewhat similar to the above-described esters of the fatty acids. It has the formula CH2(C02CHg)2, and boils at 181°. It may be prepared by treating potassium cyan-acetate with methyl alcohol and hydrochloric acid. On saponification with alcoholic potash it yields malonic acid, which melts at 132°, and serves well for the identification of the ester. 

It was first artificially prepared by Tiemann from the glucoside coni-ferin, which occurs in the cambium of various coniferous woods. The constitution of vanUlin is that of methyl protocatechuic aldehyde—... 

Camphor, Cj HjgO, occurs in the wood of the camphor tree Laurus camphora) as dextro-camphor. This is the ordinary camphor of commerce, known as Japan camphor, whilst the less common laevo-camphor is found in the oil of Matricaria parthenium. Camphor can also be obtained by the oxidation of borneol or isoborneol with nitric acid. Camphor may be prepared from turpentine in numerous ways, and there are many patents existing for its artificial preparation. Artificial camphor, however, does not appear to be able to compete commercially with the natural product. Amongst the methods may be enumerated the following —... 

Nitrobenzene, CgH5N02, also known as oil of mirbane, is an artificially prepared benzene derivative, having a coarse, but powerful odour resembling that of oil of almonds. Its coarse odour renders it quite unsuitable for fine perfumery, but it finds considerable employment in the manufacture of cheap soaps, polishes, and other articles where more or less rancid fats are used, as it covers the bad odour of the fat and gives the product a coarse almond perfume. 

There are a number of nitro-compounds known under the name of artificial musk, all of which may conveniently be grouped together here. The natural odorous constituents of musk appear to be, in the main, ketonic compounds free from nitrogen, so that the term artificial musk must be understood to mean artificially prepared bodies, having musklike odours, but not having any direct chemical relationship with natural musk perfume. 

Molecular sieves (zeolites) are artificially prepared aluminosilicates of alXali metals. The most common types for gas chromatography are molecular sieve 5A, a calcium aluminosilicate with an effective pore diameter of 0.5 nm, and molecular sieve 13X, a sodium aluminosilicate with an effective pore diameter of 1 nm. The molecular sieves have a tunnel-liXe pore structure with the pore size being dependent on the geometrical structure of the zeolite and the size of the cation. The pores are essentially microporous as the cross-sectional diameter of the channels is of similar dimensions to those of small molecules. This also contrilsutes to the enormous surface area of these materials. Two features primarily govern retention on molecular sieves. The size of the analyte idiich determines whether it can enter the porous... 

Examples Infrared spectroscopy is employed to compare samples of chloramphenicol palmitate (biologically active form) recovered from chloramphenicol palmitate mixture vis-a-vis an artificially prepared mixture of authentic sample consisting 10 per cent of the inactive polymorph . 

Francium (Fr, [Rn] . 1), name and symbol, after France, the country where it was prepared (Curie Institute in Paris). Discovered (1939) by Marguerite Perey. Very rare in nature, artificially prepared, highly radioactive. 

For many years the reference standard commonly referred to is sulfur from troilite of the Canyon Diablo iron meteorite (CDT). As Beaudoin et al. (1994) have pointed out, CDT is not homogeneous and may display variations in " S up to 0.4%o. Therefore a new reference scale, Vienna-CDT or V-CDT has been introduced by an advisory committee of IAEA in 1993, recommending an artificially prepared Ag2S (IAEA-S-1) with a S Svcdt of —0.3%o as the new international standard reference material. 

Carbon black includes several forms of artificially prepared carbon, such as furnace black, channel black, lamp black, and animal charcoal. It is a finely divided form of carbon consisting of particles of extremely fine size. It is obtained by partial combustion (in 50% required air) of vapors of heavy oil fraction of crude oil in a furnace or by thermal cracking of natural gas. Carbon black is used in many abrasion-resistant rubber products including tire treads and belt covers. It also is used in typewriter ribbons, printing inks, carbon paper, and paint pigments. It also can be an absorber for solar energy and UV radiation. 

The most important use of this compound, the principal ore of mercury, is for making mercury metal and its salts. Another major application is pigment. Artificially prepared scarlet product, vermilion, is used as artists pigment... 

Because of the practical importance of Hdfers discovery, the Academy of Sciences at Paris offered a prize for the best paper (a) on a chemical investigation of borax and sedative salt and the earth of crude East Indian borax (b) on the artificial preparation of borax or sedative salt or on a satisfactory substitute for borax, especially for soldering, and (c) on the discovery of natural sedative salt (boric acid) elsewhere than m the marsh of Monte Rotondo (107). 

In 1947 F. A. Paneth (10) pointed out that there was no justification in considering artificially prepared elements as different from those which occurred naturally. He therefore laid down the rule that the discoverers of such elements had the same right to name them as did the discoverers of any element. Perrier and Segre at once proposed the name technetium,... 

The failure to discover francium earlier is easy to understand when it is remembered that the half-life of the longest lived isotope is only 21 minutes. This gives the element the distinction of being the most unstable to radioactive disintegration of all elements up to number 98 (38). It is also noteworthy that this is the only element in the group discussed in this chapter which was not discovered by artificial preparation in the laboratory. Nevertheless, the rarity of actinium in nature is so great that this element is best prepared artificially when its properties or those of its daughter elements are to be studied. 

Saltpeter plus charcoal yields an alkali salt which hath a taste like that of the Salt of Tartar [potassium carbonate], and they differ but little in virtue.He does not say they are identical, though they would both be impure potassium carbonate. There simply did not exist at this time a clear conception of the idea of chemical substance, defined by material composition. The chief means of identifying an artificially prepared body was by its method of preparation. The inevitable presence of impurities made precise identification by explicit properties uncertain in any case, and here Lemery exhibits proper caution in indicating only the similarity rather than the identity of salt of tartar and the product of charcoal in molten saltpeter. 

The precision of an analytical procedure expresses the closeness of agreement (degree of scatter) between a series of measurements obtained from multiple samples of the same homogeneous sample under prescribed conditions. Precision is usually investigated at three levels repeatability, intermediate precision, and reproducibility. For simple formulation it is important that precision be determined using authentic homogeneous samples. A justification will be required if a homogeneous sample is not possible and artificially prepared samples or sample solutions are used. 

Titrations of artificially prepared mixtures containing phosphate, calcium, citrate, and sometimes proteins have been employed to study the precipitation of calcium phosphate and the inhibitory effect of citrate thereon (Boulet and Rose 1954 Eilers et al 1947 Wiley 1935). The technique is valuable for basic studies because the composition of the system can be controlled. 

Naturally occurring or artificially prepared supercoiled DNA molecules can often be separated by electrophoresis into about ten forms, each differing from the other by one supercoiled turn and by ALA = 1 (Fig. 5-20). The relative amounts of these topological isomers form an approximately Gaussian distribution. The isomers apparently arise as a result of thermal fluctuations in the degree of supercoiling at the time that the circles were enzymatically closed.202... 

PRILLS. Small, round, or adcular aggregates of a material, usually a fertilizer, that are artificially prepared, In tlie explosives field, prills-and-oil consists of 94% coarse, porous ammonium nitrate prills and 6% fuel oil,... 

Experiments in the artificial preparation of titanium dioxide appear to show that rutile is the most stable form and produced at the highest temperature, brookite at a lower temperature, and octahedrite (anatase) at a still lower temperature. 

Wohler is regarded as a pioneer in organic chemistry as a result of his (accidental) synthesizing urea in 1828, which electrified the scientific community. Until 1828, it was believed that organic substances could only be formed under the influence of the vital force in the bodies of animals and plants. Wohler proved by the artificial preparation of urea from inorganic materials that this view was false. Urea synthesis was integral for... 

The surface or interfacial phenomena associated with colloidal systems such as emulsions and foams are often studied by means of experiments on artificially prepared flat surfaces rather than on the colloidal systems themselves. Such methods provide a most useful indirect approach to the various problems involved. 

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