Properties of ClsTrans Isomers QUESTIONS sasune that equlum

Properties of Cls-Trans Isomers QUESTIONS . sasune that equlumc were aechieved in Part A Which aoid is the stable? 2. Same dliaclds can lose a molecule of water when the two carboxyl groups react to foma oyclic anhydride. Phthalic acld is a diacid that reacts as follows COH hest Maleic acid also can lose a molecule of water and form maleic anhydride. Which structural somer, cis or trans, do you predict it is? Fumaric acid cannot do this. Explain. 3. What do each of he folowing experiments contribule to your knowledge of the structure of each isomer? a The melting point determination. b. The reactions of solutions of each acid with the indicator, thymol blue. c. The reactions of each with sodium carbonate. d. The reactions of each with magnesium 208

Solution

1. Most stable acid would have greatest stabilization of the conjugate anion.

2. phthalic acid forms phthalic anhydride by loss of water molecule.

maleic acid is a cis isomer and thus fcan loose water molecule easily. Its isomer fumaric acid having trans configuration have -COOH on opposite sides and thus cannot loose water to form such an structure.

3. Results of experiment to determine structure

a. melting point helps to determine the cis and trans isomer. Trans-isomers are more stable and thus have higher melting points compared to the cis-isomers.

b. thymol blue is an indicator which tells us if we are dealing with an acidic or a basic solution. the color change confirms where the pH lies for the solution.

c. If free acid is present it would react with a base as sodium carbonate to generate CO2 gas in the system.

d. With magnesium carboxylic acid like the one above reacts to form conjugate base of acid and gives off hydrogen gas.