Structure Determination of Tartaric acid
Structure Determination of Tartaric Acid
1. Elemental analysis and molecular weight determination shows that the molecular formula of tartaric acid is C4H6O6.2. Tartaric acid on reduction with HI forms succinic acid which contains four C-atoms joined in straight chain.
3. It does not decolourise Br2 water or alk. KMnO4 solution. Hence it does not contain multiple bond between two C-atoms.
4. Tartaric acid changes the colour of blue litmus to red and also gives brisk effervescence with the saturated solution of NaHCO3 which confirm the presence of acidic group.
5. The presence of two – COOH groups is confirmed by the formation of two series of salts with alkalis and esters on warming with an alcohol in presence of H2SO4.
6. It is fairly stable and it does not evolve CO2 on heating. Hence the two – COOH groups must be attached to two different C-atoms.
7. It gives chloro derivative when treated with PCl5. Hence it has the OH group. The di-ester of tartaric acid on treatment with acetic anhydride or acetyl chloride gives diacetyl derivative. This indicates the presence of two - OH groups in the molecule.
8. Since it is stable acid so, two - OH groups are linked to two separate C-atoms.
From the above facts and evidences the possible structure of tartaric acid may be-
