Zone Melting and Differential Thermal Analysis of Some Organic Compounds

Abstract

Techniques of zone melting were applied to systems of organic compounds using a simple apparatus which allowed the passage of 18 molten zones through the sample during a single run.Spectrophotometric analysis indicated that the methyl violet concentration in naphthalene could be lowered to 1 p.p.m. by a single passage through the 18-zone column. Similarly, combustion of samples followed by counting of the CO2 in an ionization chamber showed that the concentration of carbon-14labeled naphthalene in benzoic acid could be lowered to less than one part per 10 million using this zone refiner.

Zone Melting of Organic Compounds

“…If a labeled impurity is added to the system, one must establish the relationship between the added impurities and the unknown impurities present. Thus zone melting a material free of one labeled impurity in no way establishes the absolute proof of removal of other impurities from the system (74,113,144,159,198,237). Electrical conductivity measurements have been used to determine trace quantities of known metal impurities.…”

“…10. Experimental Segregation Data for Organic Compounds Few measurements of concentration profiles of zone melted organic materials have been made (12,113,144,193,236,270,273). The few results (113,144,236,270,273) on binary eutectic-forming organic systems may be summarized as follows.…”

“…Experimental Segregation Data for Organic Compounds Few measurements of concentration profiles of zone melted organic materials have been made (12,113,144,193,236,270,273). The few results (113,144,236,270,273) on binary eutectic-forming organic systems may be summarized as follows. Although the over-all separation can be correlated on the basis of the boundarylayer treatment, the concentration profiles are vastly different from any of those expected for a eutectic-forming mixture.…”

Differential Thermal Analysis

“…Subsequent applications (52) resulted in determination of heats of fusion and degree of crystallinity of polyamides. PHASE EQUILIBRIA DTA was employed to obtain the solid-liquid phase diagram for a dipamide-sebacamide copolymer (52) and the phenanthrene-anthracene system (44) In the last investigation, Joncich and Bailey (44) pointed out the sensitivity of the technique to determination of effectiveness of zone refining of some organic compounds. Some of the other systems that have been investigated, employing DTA as a principal method, are: alkali metal chloridescobalt(II) chloride (54); plutonium trichloride with sodium and lithium chlorides ( 14), and potassium chloride (11); rubidium oxide-niobium pentoxide (83); lithium oxide-vanadium pentoxide (56); alkali metal chlorides-titanium dichloride (27); gallium-tellurium (73);…”

Interactions Between Pharmaceutical Compounds by Thermal Methods

“…Measurements of dissociation constants using the glass electrode have been reported but agreement with constants obtained by other means is poor (9). Kolling et al (10,11) utilized the glasscalomel cell for determining dissociation constants for various bases and salts using a comparative potentiometric method. This procedure does not, however, involve the explicit measurement of solvated hydrogen ion activity.…”