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Determination of Melting Point of Metal Complexes Of 1, 2-Dihydroxyanthraquinone-based Azo Ompound by Open Capillary Method (CAT#: STEM-PPA-0084-YJL)

Introduction

Azo compounds are the largest and most versatile class of organic colorants. Currently they account for more than 50% of the total number of colored compounds manufactured and have received much attention in both academic and applied research. They are designed to impart their color either as dyes or pigments on an array of substrates in the decorative and /or protective capacity. The technical properties of azo compounds are enhanced in the presence of metal ions which form chelates with these colored compounds. This is due the fact that azo metal complexes have been reported to be more light stable, possess interesting electronic features that allow for easier control of wavelength by selection of the appropriate substituent groups and exhibit better thermal stability; when compared to the azo compounds themselves. Chromium and Copper complexes are reportedly stable in weak acids and alkalis




Principle

Melting point is a characteristic property of solid crystalline substance. It is the temperature at which the solid phase changes to the liquid phase. This phenomenon occurs when the substance is heated.
In all major pharmacopoeias the open capillary method is described to determine the melting point (slip point) for fats, fatty acids, paraffin, and waxes. In a glass capillary tube open at both ends (1), 10 mm of sample is introduced (2), chilled to a given temperature and immersed into a water bath (3/4). The melting point with open capillary, also known as slip point or slip melting point, is the temperature at which the substance begins to rise in the capillary due to the effect of the increasing temperature and buoyancy.

Applications

Chemical industry; Cosmetic/pharmaceutical industry

Procedure

1. Prepare the substance.
2. Affix one of the capillaries to a thermometer.
3. Place the thermometer with an affixed capillary into a glass.
4. Increase the temperature.

Materials

• Sample Type: crystalline compounds