Pure state

C, b.p. 156 C. The most important of the terpene hydrocarbons. It is found in most essential oils derived from the Coniferae, and is the main constituent of turpentine oil. Contains two asymmetric carbon atoms. The (- -)-form is easily obtained in a pure state by fractionation of Greek turpentine oil, of which it constitutes 95%. Pinene may be separated from turpentine oil in the form of its crystalline nitrosochloride, CioHigClNO, from which the ( + )-form may be recovered by boiling with aniline in alcoholic solution. When heated under pressure at 250-270 C, a-pinene is converted into dipentene. It can be reduced by hydrogen in the presence of a catalyst to form... 

A measure of the purity or cohereuce of a system is given by jpf = 1 for a pure state and S. for a mixed state the greater the degree of mixture the lower will be the purity. A general expression for the... 

Tr(p ). For an initially thennal state the radius < 1, while for a pure state = 1. The object of cooling is to manipulate the density matrix onto spheres of increasingly larger radius. 

Amorphous boron has not been obtained in the pure state. Crystalline boron is a black powder, extremely hard, with a metallic appearance but with very low electrical conductivity. 

Enzymes are proteins of high molecular weight, several of which have been isolated in a pure State consequently their precise nature is in some instances still obscure. They form solutions in water and in dilute salt solutions, and are precipitated when such solutions are saturated with ammonium sulphate. 

The isolation of enzymes in a pure state is frequently a matter of great difficulty owing to their instability, their low concentrations in plant and animal tissues, and also to their colloidal nature. The methods employed depend upon the physical and chemical nature of the enzyme in question. In the following experiments, no attempt has been made to isolate enzymes in a high slate of purity. 

Alternatively, dissolve 0-5 g. of the tertiary amine and 0-5 ml. of methyl iodide in 5 ml. of dry ether or benzene, and allow the mixture to stand for several hours. The methiodide precipitates, usually in a fairly pure state. Filter, wash with a little of the solvent, and recrystallise as above. 

Hydrocarbons and di-esters, otherwise rather inaccessible in a pure state, are conveniently prepared by electrol3rtic (anodic) synthesis. Thus simple couphng... 

Some neutral compounds (e.g., methyl alcohol) cannot be salted out with potassium carbonate distillation of the saturated aqueous potassium carbonate solution frequently yields the organic compound in a comparatively pure state, or at least in sufllciently concentrated a form to enable certain derivatives to be prepared. 

Normal hydrogen at room temperature contains 25% of the para form and 75% of the ortho form. The ortho form cannot be prepared in the pure state. Since the two forms differ in energy, the physical properties also differ. The melting and boiling points of parahydrogen are about O.loC lower than those of normal hydrogen. 

The element is a gray-white metalloid. In its pure state, the element is crystalline and brittle, retaining its luster in air at room temperature. It is a very important semiconductor material. Zone-refining techniques have led to production of crystalline germanium for semiconductor use with an impurity of only one part in lOio. 

For example, a thiazole-cyclohexane solution at 25 C is less viscous than the ideal system, and the deviation from ideality can be explained assuming that in solution there is a breakage between the existing association of the thiazole molecules in pure state (157). 

The advantage of this definition is that it does not depend on measuting the tangent of the response curve, although the variation ia the value of the blending octane number is greater. Typically, BONs are measured at an 80/20 mixture. This technique is also usehil when trying to measure the octane of a compound such as butane or methanol that is difficult or impossible to measure ia its pure state. 

Hydrogen atoms can be produced in significant quantities in the gas phase by the action of radiation on or by extreme heating of H2 (3000 K). Although hydrogen atoms are very reactive, these atoms can persist in the pure state for significant periods of time because of the inabiUty to recombine without a third body to absorb the energy of bond formation. 

Mercurous Nitrate. Mercurous nitrate [10415-75-5] Hg2N20 or Hg2(N02)2, is a white monoclinic crystalline compound that is not very soluble in water but hydrolyzes to form a basic, yellow hydrate. This material is, however, soluble in cold, dilute nitric acid, and a solution is used as starting material for other water-insoluble mercurous salts. Mercurous nitrate is difficult to obtain in the pure state directly because some mercuric nitrate formation is almost unavoidable. When mercury is dissolved in hot dilute nitric acid, technical mercurous nitrate crystallizes on cooling. The use of excess mercury is helpful in reducing mercuric content, but an additional separation step is necessary. More concentrated nitric acid solutions should be avoided because these oxidize the mercurous to mercuric salt. Reagent-grade material is obtained by recrystaUization from dilute nitric acid in the presence of excess mercury. 

Nickel sulfide, NiS, can be prepared by the fusion of nickel powder with molten sulfur or by precipitation usiag hydrogen sulfide treatment of a buffered solution of a nickel(II) salt. The behavior of nickel sulfides ia the pure state and ia mixtures with other sulfides is of iaterest ia the recovery of nickel from ores, ia the high temperature sulfide corrosion of nickel alloys, and ia the behavior of nickel-containing catalysts. 

Peroxosulfiiric Acids and Their Salts. Two kiads of peroxosulfiiric acid are known peroxomonosulfuric and peroxodisulfuric acids. Neither is available commercially ia the pure state. The name Caro s acid is commonly used as a synonym for peroxomonosulfuric acid, but is better reserved for the equiUbrium mixture with sulfuric acid. 

Potassium superoxide is produced commercially by spraying molten potassium iato an air stream, which may be enriched with oxygen. Excess air is used to dissipate the heat of reaction and to maintain the temperature at ca 300°C. It can also be prepared ia a highly pure state by oxidizing potassium metal that is dissolved ia Hquid ammonia at —50° C. 

Alkyl hydroperoxides can be Hquids or soHds. Those having low molecular weight are soluble in water and are explosive in the pure state. As the molecular weight increases, ie, as the active oxygen content is reduced, water solubiUty and the violence of decomposition decrease. Alkyl hydroperoxides are stronger acids than the corresponding alcohols and have acidities similar to those of phenols, Alkyl hydroperoxides can be purified through their alkali metal salts (28). 

Other Phosphorus—Nitrogen Compounds. Of the binary phosphoms—nitrogen compounds, only triphosphoms pentanitride [12136-91 -3] 3 5 been obtained in a pure state. It can be prepared by treatment of P S q with ammonia and subsequent heating of the intermediate... 

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