Answer to Question #95523 in Organic Chemistry for Okoro Wenebi

Question

1: Discuss Malic acid, state it's methods of preparation,physical and chemical properties and it's importance

Answer 1

 (S)-malate is an intermediate, formed by the addition of an -OH group on the si face of fumarate. It can also be formed from pyruvate via anaplerotic reactions.Malate is also synthesized by the carboxylation of phosphoenolpyruvate in the guard cells of plant leaves.

Properties:

• Chemical formula C₄H₆O₅
• Molar mass 134.087 g·mol⁻¹
• Density 1.609 g⋅cm⁻³
• Melting point 130 °C
• Solubility in water 558 g/L (at 20 °C)
• pK_a1 = 3.40 pK_a2 = 5.20

Self-condensation of malic acid with fuming sulfuric acid gives the pyrone coumalic acid. Malic acid was important in the discovery of the Walden inversion and the Walden cycle, in which (−)-malic acid first is converted into (+)-chlorosuccinic acid by action of phosphorus pentachloride. Wet silver oxide then converts the chlorine compound to (+)-malic acid, which then reacts with PCl₅ to the (−)-chlorosuccinic acid. The cycle is completed when silver oxide takes this compound back to (−)-malic acid.