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Lesson 10 B. SUBSTITUTED CARBOXYLIC ACIDS: HALOGEN, KETO AND HYDROXY ACIDS AND THEIR IMPORTANT REACTIONS
Module 3. Carboxylic acids
Lesson 10B
SUBSTITUTED CARBOXYLIC ACIDS: HALOGEN, KETO AND HYDROXY ACIDS AND THEIR IMPORTANT REACTIONS
1. Reactions with alkali (Neutralization)
- Carboxylic acids are recognized by their acidity
- Like conventional acids (HCl, H2S04, HNO3 etc), carboxylic acids (R-COOH) also react with aqueous hydroxides (e.g. NaOH) to form salt and water = used for determination of the acid
- Reaction with aqueous sodium bicarbonate and carbonate forms salt, water and evolve carbon dioxide - effervescence -forms the basis for detection of –COOH group in an organic compound
2R-COOH + Na2CO3 = 2R-COONa + H2O + CO2
R-COOH + NaHCO3 = R-COONa + H2O + CO2
R-COOH + NaHCO3 = R-COONa + H2O + CO2
- When the salt is treated with mineral acid- it is converted back into carboxylic acid
R-COONa + HCl = RCOOH + NaCl
Salt mineral acid carboxylic acid
Salt mineral acid carboxylic acid
- Reducing agent - Lithium aluminum hydride - LiAlH4 -gives excellent yield, but somewhat expensive
- By heating calcium salt of the acid at high temperature
- When a mixture of Caformate and Ca salt of higher acid is heated - aldehyde will form
(HCOO)2Ca + (R-COO)2Ca = 2RCHO + 2CaCO3
aldehyde
- When Ca salt of an acid other than formic acid is heated – ketone will form
- Chlorine reacts with carboxylic acids to form choloro substituted carboxylic acids
Last modified: Thursday, 27 September 2012, 6:34 AM