Question

On the lab identifying an unknown analgesic by melting temperature, my unknown was acetaminophen. The question is to explain the identification method using data (melting temperature data and the Rf values)

Answer 1

The values of melting point of acetaminophen are in the range of 168-172⁰C. Molar mass (g/mol) 151.16, Its solubility in cold water is 1.43 g / 100 cm³ but it is much more soluble in hot water (5g / 100 cm³) and in ethanol (1.43 g / 100 cm³).

The Rƒ value for acetaminophen is 0.24 [Indian Pharmacopoeia], Rƒ values of standard sample-Paracetamolum Eur. Pharmacopoeia (Rƒ=0.65) [ European Pharmacopoeia]. Probably you may need USP (United States Pharmacopoeia) i do not have that info right now. It is experimentally determined value.

The Rƒ is calculated by dividing the distance the compound traveled from the original position by the distance the solvent travelled from the original position (the solvent front).

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