Lab # 4 PHS244

Carboxylic acid

Carboxylic acids are organic compounds characterized by the presence of at least one carboxyl group (- COOH) The general formula of a carboxylic acid is R-COOH.

Classified according to substituent bonded to carboxyl group. Aliphatic acid (alkyl group) Aromatic acid (aryl group) Carboxylic acid

Acitic acid Cetric acid Formic acid Tartaric acid Carboxylic acid

Benzoic acid Phthalic acid Carboxylic acid

Acetic Acid is found in vinegar and is responsible for giving it the sour taste. Salicylic acid is used in acne creams, synthesis of aspirin. Also used as a food preservative. Citric Acid is found in most citrus fruits. It gives the tangy taste to lemons, limes, grape fruits and oranges. it is a natural preservative and used in both foods and soft drinks. It is also used in some bathroom and kitchen cleaning solutions. Benzoic acid is very useful in the food industry, personal care industry and in medicine as well, present in various products, including sauces, jams, jellies and candied fruits. in mouthwash, toothpaste, powder, lipstick and facial cleanser. Carboxylic acid uses:

Physical properties Acetic AcidFormic acid liquid State colorless Color Vinegar odorPungent odorodor non-luminous non smoky flame Flammability completely miscible in water solubility red color (acid) Effect on L.P

Citric acidTartaric acid solidSolidState White crystalsWhite powderColor characteristic odor odor non-luminous non smoky flame Flammability completely miscible in water solubility red color (acid) Effect on L.P Physical properties

Benzoic AcidPhthalic Acid solid State Colorless crystals White crystalline powderColor characteristic odor Odor luminous smoky flame Flammability insoluble in water But in NaOH insoluble in water But in NaOH solubility red color (acid) Effect on L.P Physical properties

Salicylic Acid solidState colorless to white crystalsColor odorlessodor luminous smoky flameFlammability insoluble in water But in NaOH solubility red color (acid)Effect on L.P Physical properties

Chemical Tests Specific tests 1. HgCl2 test 2-Reduction test 3-Esterification test I.Formic acid & Acetic acid 1- Fenton’s test 2-Deniges’ test II.Tartaric acid & Citric acid 1-Phthalein test 2- Fluorescence test III.phthalic and benzoic acid 1-Esterification test 2-Formaldehyde test 3-Phthalein test IV.Salicylic acid general test Neutralization test

General test Neutralization test: Procedure: Add 0.5 ml or few mg of carboxylic acid + dil. NH4OH until ammonia odor appear  on hot plate : until ammonia odor disappear  on cold: add one drop of N.Fecl3 Results: Formic acid and acetic acid gives: red blood color. Tartaric acid and citric acid gives: lemon yellow color. Benzoic acid and phthaic acid gives :buff ppt. Salicylic acid (directly without add NH4OH ) gives: violet color. Chemical Tests

Chemical Tests Neutralization test results: Reed blood color (Formic & acetic) Lemon yellow color (Tartaric & citric) Buff ppt (Benzoic & phthalic)

Esterfication Reaction between alcohols and carboxylic acids to make esters. Esters usually have pleasant fruitlike odors.

Esterfication Reaction Esters are produced when carboxylic acids are heated with alcohols in the presence of an acid catalyst. The catalyst is usually is concentrated sulphuric acid (Conc.H2So4 )

Specific tests I. Formic acid & Acetic acid 1. HgCl2 test: Procedure: 1 ml of for. acid or Ace. acid + 1 ml of HgCl2 then warm in water bath for 5 min. Results: Formic acid: white ppt. Acetic acid: no reaction.

Specific test I. Formic acid & Acetic acid 1. HgCl2 test : Formic acidAcetic acid

Specific tests I. Formic acid & Acetic acid 2. Reduction test: Procedure: 1 ml of for. acid or Ace. acid + 1 ml of Na2CO ml KMnO4 Results: - Formic acid: de-colorization violet color of KMnO4 and formation brown ppt. - Acetic acid: no reaction.

Specific tests I.Formic acid & Acetic acid 2- reduction test

Specific tests I. Formic acid & Acetic acid 3- Esterification test: Procedure: 1 ml of ethanol + 1 ml of for. acid or Ace. Acid, 2 drops of conc. H2SO4 then warm in water bath for 5 min. In a backer prepare Na2Co3 solution. Add the content of the test tube into the backer. Results : Formic acid: no reaction Acetic acid: fruity odor

Specific tests II. Tartaric acid & Citric acid 1- Fenton’s test: Procedure: few mg of tar. acid or cit. acid + 1 ml of FeSO4 + 1 ml of H2O ml of 10% NaOH. Results : Tartaric acid: purple or brown ppt. Citric acid: no reaction.

Specific tests II. Tartaric acid & Citric acid 2- Deniges’ test: Procedure: few mg of tar. acid or cit. acid + 1 ml of deniges 1, then warm in water bath for 5 min. After heating, add 1ml of deniges 2. Results : - Tartaric acid: de-colorization without formation of white ppt. - Citric acid: de-colorization and formation white ppt.

Specific tests III.phthalic and benzoic acid 1- Phthalein test: Procedure: few mg of phth. acid or ben. acid + few mg of phenol ml of conc. H2SO4 then fusion with flame. In a baker, add 10 ml of 10% NaOH. Add the content of the test tube into the baker. Results : Phthalic acid: pink color. Benzoic acid: no reaction.

Specific tests III.phthalic and benzoic acid 1- Phthalein test Benzoic acid Phthalic acid

Specific tests III. phthalic and benzoic acid 2. Fluorescence test: Procedure: few mg of phth. acid or ben. acid + few mg of resorcinol ml of conc. H2SO4 then fusion with flame. In a baker, add 10 ml of 10% NaOH. Add the content of the test tube into the baker. Results : -Phthalic acid: reddish green color. Add water, green fluorescent. -Benzoic acid: no reaction

Specific tests IV. Salicylic acid 1- Esterification test: Procedure: few mg of sali. acid + 1 ml of methanol + 2 drops of conc. H2SO4 then warm in water bath for 5 min. In a backer prepare Na2Co3 solution. Add the content of the test tube into the backer Results: Salicylic acid: vicks odor

Specific tests IV. Salicylic acid 2- Formaldehyde test: Procedure: few mg of sali. acid + 1 ml of formaldehyde + 2 drops of conc. H2SO4. Results : Salicylic acid: crimson red color.

Specific tests IV. Salicylic acid 2- Formaldehyde test: Salicylic acid

Specific tests IV. Salicylic acid 3-Phthalein test: Procedure: few mg of sali. acid + few mg of phthalic anhydride ml of conc. H2SO4 then fusion with flame. In a baker, add 10 ml of 10% NaOH. Add the content of the test tube into the baker. Result : Salicylic acid: pink color.

Specific tests IV. Salicylic acid 3-Phthalein test:

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