Thermodynamic Studies on Melting Some α- and β-Derivatives of Naphthalene

1979 ◽  
Vol 32 (1) ◽  
pp. 49 ◽  
Author(s):  
SC Khetarpal ◽  
K Lal ◽  
HL Bhatnagar

Methods for determining volume changes on melting have been briefly reviewed. A new apparatus has been described which is simple in operation, accurate in measurements and is free from some of the major limitations of the apparatuses used earlier. It has been used to determine volume changes on melting of α- and β-derivatives of naphthalene (C10H7X; X = NH2, OH, COOH), as well as coefficients of cubical expansion of the solid compounds (α) and their melts (α'). The application of the apparatus has been extended to determine the densities of the compounds at any temperature both when entrapped air is present (d) and when it is completely absent (d'). An electrical method using a modified glass calorimeter has been employed for the measurement of latent heats of fusion, ΔHf. From the experimentally determined values of ΔVf/Vs,d', α and ΔHf, the molar volume of the solid compound at the melting point (V8), that of the melt at the melting point (V1), the entropy of fusion (ΔSf), the variation of the melting temperature with pressure [(∂T/∂P)v] and the compressibility coefficient of the solid compounds (β) have been calculated and the results discussed.

Alkali thiocyanates are remarkable for their low melting-points (KSCN 175°C; RbSCN 195°C). Mechanisms of melting of the sodium and potassium salts have been investigated by determining ionic conductivities of solid and melt, viscosities of the melts and, in the case of the potassium salt, entropy and volume changes on melting. It seems likely that the low melting-points of alkali thiocyanates arise from the contribution of association complexes in the melt to the entropy of fusion. These increase the entropy of fusion without requiring large heat or volume changes. In such cases melting-points tend to be low in accordance with the equation, T f = H f / S f . Marked homophase premelting is observed in solid KSCN; the experiments show hardly any discontinuity in volume at the melting-point.


1932 ◽  
Vol 7 (3) ◽  
pp. 285-292 ◽  
Author(s):  
J. Ansel Anderson

Khapli wheat leaves contain a very small quantity of a trihydroxydimethoxyflavone, tricin. Marquis yields a trace of the same compound. These two varieties also contain water-soluble coloring matters which are apparently glucosides of tricin or of a closely related compound. Dyeing tests carried out with six other wheat varieties indicate that all contain essentially the same coloring matters.Methylation of tricin and hydrolysis of the resulting O-trimethyltricin yielded 3,4,5-trimethoxybenzoic acid and 2-hydroxy-4,6-dimethoxyacetophenone. It was therefore assumed that tricetin, the pentahydroxyflavone derived from tricin, was 5,7,3′,4′,5′-pentahydroxyflavone. This was synthesized from 3,4,5-trimethoxybenzoic acid and phloracetophenone by the Allan-Robinson method. Mixed melting-point determinations showed that its O-pentamethyl and O-penta-acetyl derivatives are identical with the corresponding derivatives of tricetin. The dyeing properties and color reactions of synthetic and natural tricetin are identical and are in fair agreement with those described by Badhwar, Kang and Ventkataraman (3, p. 1111) who recently reported the synthesis of the same compound.


2020 ◽  
Vol 36 (05) ◽  
pp. 976-979
Author(s):  
Neeta Sinha

The derivatives of 3-ferrocenyl isocoumarin were synthesized by the condensation of substituted homothphalic anhydride with ferrocene using phosphoric acid or anhydrous aluminium chloride as cyclising agent. Substituted homophthalic acid did not condense with ferrocene so homophthalic acids were converted into their anhydride and then allowed to react with ferrocene in the presence of polyphosphoric acid or in the presence of anhydrous aluminium chloride using dichloromethane as the solvent to give 3-ferrocenyl isocoumarins. 7-Methoxy, 6-methyl, 5,7-dihydroxy, 6,7-dimethoxy and 5,7-dimethoxy derivatives of 3-ferrocenyl isocoumarin were synthesized. All the compounds were characterised by melting point determination, elemental and spectral analysis.


1956 ◽  
Vol 34 (9) ◽  
pp. 1243-1248 ◽  
Author(s):  
D. W. Davidson

With isopentane as the dilatometric liquid, CH3OD was examined between 120 °K. and the melting point. There is evidence of two transitions within the solid: one, in the vicinity of 158 °K., appears to be a gradual transition, the other, at 163 °K., a first-order one. The corresponding molar volume changes are 0.04 and 0.43 ml. A further change of volume of 2.67 ml./mole occurs at the melting point. These results are compared with recent dilatometric results for CH3OH and discussed with reference to the available calorimetric data. The molar volume of CH3OD is slightly greater than that of CH3OH in both liquid and solid forms.


In recent years, the practical requirements of the metal industries have made it necessary to study the factors which govern the production of good castings. One of the most important of these factors is the change of volume which accompanies solidification. The experimental methods which have hitherto been used to determine this change have given discordant results, and it has seemed desirable to devise a new method, less liable to error. The new form of volumenometer which is the subject of this paper is intended to eliminate most of the errors inherent in the older methods. It has been applied to the measurement of the volume changes of two eutectic alloys, those of lead and tin and of tin and bismuth, the former of which contracts during solidification, whilst the latter shows a distinct expansion. The results indicate that the method is trustworthy. Previous Methods of Measurement . The older methods, which have been used for the experimental determination of the changes in volume, associated with the change in state of bodies, may be divided into the following classes:— ( a )The coefficients of expansion of the solid and liquid, over limited ranges of temperature, are measured and the volume change occurring at the melting point is found by extrapolation. The coefficient of expansion of the solid is found either by direct measurement of the linear expansion or deduced from measurements derived from some hydrostatic method in which Archimedes’ Principle is employed. The expansion of the liquid melt is inferred from observations on some dilatometric or hydrostatic method.


Author(s):  
Ganesh S. Andhale ◽  
Giles D. ◽  
Amit K. Das ◽  
Basavraj Metikurki ◽  
Gurubasavrajswamy PM

In the present study we have synthesized ester prodrugs (Pa-i) of Metoprolol (I) by using pthalic anhydride and derivatives of succinic and maleic anhydride. Different codrugs (COa-i) were synthesized from prodrugs of metoprolol. All the codrugs were characterized by melting point, FTIR, NMR and Mass Spectroscopy. The chemical hydrolysis of COa-i were investigated at the pH 1.2, 6.8 and 7.4. Presence of maleate, methyl maleate, dimethyl maleate and succinate group as linker were found to possess good hydrolysis when compared to that of other substitutes. Among the synthesized codrugs, COf is found to be the best one among the series


2018 ◽  
Vol 22 (2) ◽  
pp. 267-271
Author(s):  
V.G. Paliy ◽  
I.G. Paliy ◽  
A.O. Dudar ◽  
D.V. Paliy ◽  
A. V. Kulyk

Successful research by scientists of new synthetic substances of various chemical groups contributes to the broadening of the arsenal of antimicrobial drugs for the prevention and treatment of purulent-inflammatory diseases. Antimicrobial drugs, as a rule, suppress pathogenic, invasive, adhesive properties and reduce the resistance of microorganisms to antibiotics in pathogens of supportive inflammatory diseases; significantly increase the effectiveness of treatment of diseases of infectious origin. The purpose of the study was to study the physicochemical, antimicrobial properties of derivatives of menthol, phenol and quinoline. The results of the study of physicochemical, antimicrobial properties of six chemical compounds of menthol, quinoline, and phenol derivatives using the principle of complex research, in which physicochemical, microbiological methods were used, are presented. There was shown that quaternary ammonium compounds of the menthol derivatives were alike white powders with a molecular weight of 581–693, a melting point of 990 to 1850° C. The chemicals are soluble in water, ethanol. Quinoline preparations have a molecular weight of 687; 756, melting point 178–2000°C; dissolved in ethanol. Compounds of phenol had a molecular weight of 111, 112, a melting point of 1020, 1100°C was soluble in ethanol. It has been established that synthesized substances possess a wide spectrum of antimicrobial action on Gram-positive, Gram-negative bacteria, Candida albicans. In antibiotic resistant strains of Staphylococci no markers of resistance to drugs containing in the molecule menthol, phenol, quinoline were found. In complex physical and chemical systems, it was important to study the coefficient of surface tension of solutions of drugs, which was an important objective physical indicator of the molecular state of various drugs. Distilled water was used as a control. Experiments were performed according to a well-known technique. According to the results of the study, in the control the surface tension of water was it was found to be 55,70 dn/cm2. In an experiment with 0,1% solution of decamethoxin; the drug number 2 was 40,80 dn/cm2 and 38,20 dn/cm2. In derivatives of quinoline (DN, drug № 4), was 39,60 dn/cm2 and 34,50 dn/cm2. Solutions of phenol (preparations №5; №6) were characterized by surface tension 32,40–43,50 dn/cm2. Surface tension of solutions of preparations depended on their chemical structure. The antimicrobial properties of the preparations were determined on the museum and clinical strains of microorganisms, which had typical tynctorial, morphological, and cultural characteristics. For a complete biological characterization in strains of Staphylococci, the formation of coagulase enzymes, lecithovitellase, hemolysins, and mannitol fermentation in anaerobic conditions were studied. At 12 museum and clinical strains of bacteria, bacteriostatic and bactericidal effects of six drugs, which are derivatives of menthol (DK, №2), quinoline (DN, №4), phenol (preparations №5, №6), have been detected. Derivatives of menthol acted bactericidal to Staphylococci at doses of 0,48-3,9 μg/ml; Quinoline derivatives in the range of 7,8–15,6 μg/ml; derivatives of phenol 31,25–62,5 μg/ml, respectively. Staphylococci were highly resistant to phenol derivatives (31,25–62,5 μg/ml). Gram-negative bacteria exhibited high resistance to quinoline and phenol derivatives (250–500 μg/ml). Summing up the results of determining the antimicrobial action of antiseptics derivatives of menthol, quinoline, it should be emphasized that the drugs have high activity in relation to Staphylococci (0,24–7,8 μg/ml). Phenol derivatives have low bacteriostatic and bactericidal effects on Gram-negative bacteria (125–500 μg/ml), which limits their use in medicine.


Melting parameters are reviewed for the nitrates of Li, Na, K, Rb, Cs and Ag, and are com­pared with values for the corresponding halides. Previously published information has been supplemented by experiments on the viscosity of molten AgNO 3 , and on the dilatometry and electrical conductivity of AgNO 3 in the solid and melt. It is suggested that the low melting points of group I nitrates, compared with the corre­sponding halides, is due to the formation of association complexes in the nitrate melts. This process could contribute a term to the overall entropy of fusion S f without greatly increasing the heat of fusion H f . Since T f = H f / S f , this would explain the unusually low melting points. The small volume changes of fusion of nitrates, where measured, and the abnormal activation energies for the viscosities of molten nitrates, support the suggested mechanism of melting.


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