Rast molecular weight determination

Closely related to magnoline is the alkaloid dauricine which has been found in Menispermum dauricum DC. by Kondo and Narita (3), and later by Manske (4) in the subterranean stems and roots of a woody liana, Menispermum canadense L., widely distributed throughout North America. It is a phenolic yellow resinous base soluble in most organic solvents. On the basis of the Rast molecular weight determination the Japanese workers... 

Pilocereine, an alkaloid occurring in several giant cacti, was assigned formula CLVII in 1957. This assignment was founded on elemental analyses, molecular weight determination (Rast), and the identification of the products obtained by reductive fission of the alkaloid, 0-methyl-pilocereine, and 0-ethylpilocereine (111). 

Molecular weights (determined by the Rast method) are also found to depend on the cooling schedule, and data have been reported in this area [19]. 

Rast method analy chem The melting-point depression method often used for the determination of the molecular weight of organic compounds. rast. meth-od rate constant physchem Numerical constant in a rate-of-reaction equation for example, = feCaACbBCcC, where and Cc are reactant concentrations, k is the... 

The Analytical section has been subjected to some changes. An electrically heated combustion furnace, some new methods of analysis, and the method of Rast for the determination of molecular weights, are also described. Chapter XLIV. on tests for some common organic substances has been completely rewritten. 

The Italian authors (141) determined the molecular weights (Rast) of their products and by chemical analysis (Kuhn) the amount of CH3 C groups in the molecule. Since 1,3-polymerized propenylbenzene would not contain pendant CH3 groups, it is now possible to calculate from their data the contribution of 1,3 polymerization for the case of anethole. Table 1 shows Secci and Memeli s data and the effect of temperature on the mechanism. Apparently 1,2 polymerization is increasing as the temperature is lowered. 

Sometimes camphor is used as the solvent (Rast method) because of its high constant ( 38). However, it is very prone to form solid solutions which vitiate this method of determining molecular weights, since it is based on the assumption that the first solid to be deposited will be the pure solvent. The use of camphor and related solvents is therefore not recommended. The possibility of obtaining solid solutions should be recognized in all cases, for this is one of the main limitations to the use of this method. 

Rast method. The melting-point depression method often used for the determination of the molecular weight of organic compounds. 

Immediate allergies can be examined by skin-prick tests, scratch tests, or use tests, and by determination of specific IgE antibodies in the patient s serum (Kanerva et al. 1991 Tarvainen and Kanerva 1999). Low-molecular-weight chemicals can be conjugated with HSA (Howe et al. 1983) before they are used in skin-prick tests or RAST examinations (Ceska and Lundkvist 1972). 

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