Purifying or Extraction of Carboxylic Acids ether RCOOH other (1)remove ether phase phase organics R-COOH other (1)remove H2O phase (2)acidify with HCI(aq) (pure) organics (2)add dilute NaOH RCOO (3)add fresh ether (or NaHCO3) Na+ H2O salts, H CI etc. Na OH phase 0 0 R-C-OH NaOH (aq) R-C-0-Na+ HCl (aq) R—C-OH soluble in ether,but not in H2O soluble in H2O,but not in ether soluble in ether,but not in H2O A carboxylic acid is more soluble in the organic phase, but its salt is more soluble in the aqueous phase. Acid-base extractions can move the acid from the ether phase into the aqueous phase and back into the ether phase,leaving impurities behind
Purifying or Extraction of Carboxylic Acids ◼A carboxylic acid is more soluble in the organic phase, but its salt is more soluble in the aqueous phase. ◼Acid–base extractions can move the acid from the ether phase into the aqueous phase and back into the ether phase, leaving impurities behind
自水标特试对 A mixture of CH2OH COOH and Benzyl alcohol Benzoic acid Dissolve in diethyl ether Mix with 0.IM NaOH Ether layer containing benzyl alcohol Water layer containing sodium benzoate Distill ether Acidify with 0.1M HCI and filter solid CHOH COOH Benzyl alcohol Benzoic acid bp 205C mp 122C
Some Important Acids Acetic acid is in vinegar and other foods, used industrially as solvent,catalyst,and reagent for synthesis. Fatty acids from fats and oils. Benzoic acid in drugs,preservatives. Adipic acid used to make nylon 66. 二 Phthalic acid used to make polyesters. 邻苯二甲酸
Some Important Acids ◼Acetic acid is in vinegar and other foods, used industrially as solvent, catalyst, and reagent for synthesis. ◼Fatty acids from fats and oils. ◼Benzoic acid in drugs, preservatives. ◼Adipic acid used to make nylon 66. ◼Phthalic acid used to make polyesters. 邻苯二甲酸 己二酸
Sec 2 PREPARATIONS OF CARBOXYLIC ACIDS Functional group transformations oPrimary alcohols and aldehydes are converted to carboxylic acids by oxidation. oAcid chlorides,acid anhydrides,esters,and amides can be hydrolyzed to their parent carboxylic acids Bond cleavage Cleavage of an alkene with hot KMnO4 produces a carboxylic acid if there is a hydrogen on the double- bonded carbon. Cleavage of an alkyne with ozone or hot permanganate. C-C bond formation Grignard Carboxylation oalkylating diethyl malonate
Sec 2 PREPARATIONS OF CARBOXYLIC ACIDS ◼Functional group transformations ⚫Primary alcohols and aldehydes are converted to carboxylic acids by oxidation. ⚫Acid chlorides, acid anhydrides, esters, and amides can be hydrolyzed to their parent carboxylic acids ◼Bond cleavage ⚫Cleavage of an alkene with hot KMnO4 produces a carboxylic acid if there is a hydrogen on the doublebonded carbon. ⚫Cleavage of an alkyne with ozone or hot permanganate. ◼C-C bond formation ⚫Grignard Carboxylation ⚫alkylating diethyl malonate
RXNs of Carboxylic Acids:An Overview Carboxylic acids transfer a proton to a base to give anions,which are good nucleophiles in SN2 reactions Like ketones,carboxylic acids undergo addition of nucleophiles to the carbonyl group In addition,carboxylic acids undergo other reactions characteristic of neither alcohols nor ketones OH Deprotonation Reduction OH 2004 Tho n/Brooks Cole Alpha substitution Nucleophilic acyl substitution Carboxylic acid
RXNs of Carboxylic Acids: An Overview ◼Carboxylic acids transfer a proton to a base to give anions, which are good nucleophiles in SN2 reactions ◼Like ketones, carboxylic acids undergo addition of nucleophiles to the carbonyl group ◼In addition, carboxylic acids undergo other reactions characteristic of neither alcohols nor ketones