Benzoic acid is used for foods while benzoin resin is used in cosmetics, lotions and soaps

Acetylsalicylic acid

Acetic acid +water

Carboxylic acids

Aliphatic carboxylic acidsFormic acid

pungent true liqid mobilyAcetic acid

colorless vinegar

Tartaric acid solid crystalline Citric acid

yellowish white odorless

Aromatic carboxylic acids

Benzoic acid

solid crystalline, yellowish white odorless

Salicylic acid

Phthalic acid solid flaky ,yellowish white

odorless

Ignition test

Aliphatic C.A: inflammable ,non luminous and no smokyAromatic C.A: inflammable , luminous and smoky

Appearance change:

formic and acetic acid volatilization tartaric acid swelling up and charring* citric acid melting and formation yellow resin*blackening benzoic, salicylic, phthalic acid melting

Color flame:No change with all

Odor:Formic ,acetic acid : no changeTartaric, citric acid: burnt sugar odor.Benzoic ,phthalic acid: irritant odor (suffocating).Salicylic acid: phenolic odor .

Residue:No residue with all except Tartaric acid : black residue. Citric acid: yellow stain.

Acid base test

Acidity test:Na2CO3 solution(conc) + acid → warm → effervescent Strong effervescent that means acid.Weak effervescent that means acidic.

Conc. Hcl test: when substance soluble in 10% NaOH that means acid .if add HcL in same test tube→ reprecipted again

Conc. HCL

Acidity test

L.P H2O acids

Reppt. effervescent

Change blue to

red

Miscible Formic Acetic

Change blue to

red

soluble tartariccitric

Not doneInsoluble

in H2O ,dil HCL but soluble

in 10%NaO

H

benzoicphthalicsalicylic

All strong acid

Preliminary test

Soda lime test:Formic and acetic acid: not done for solid only.Tartaric and citric acid: burnt sugar odor on hot.Benzoic and phthalic acid: benzene odor on hot.Salicylic acid: phenolic odor on hot.

30%NaOH:The same result of soda lime

FeCL3:No reaction with all.

Conc. H2SO4:Formic and acetic acid: effervescent due to CO2 evolution on cold.Tartaric acid : effervescent and heavy charring on hot.Citric acid: effervescent and yellow stain after long time it blackening.benzoic, phthalic and salicylic acids: no reaction

General test

Neutral FeCL3:

1 ml of acids +2ml NH4OH→ heat until complete disapperance of ammonia odor then wait 2-3 min. to cooling then add 2-3 dps of neutral FeCL3→

formic ,acetic acids: blood red color give brown if heat it.Tartaric, citric acids: lemon yellow color.Benzoic, phthalic acids: buff ppt.Salicylic acid: no need to use NH4OH just salicylic +H2O +neutralFeCL3 to give violet color.

Differentiation tests

Acetic acid Formic acid- Turbidity or whit

ppt. (Hg2CL2)HgCL2: HgCL2+acid (wait 5 min)

- Disappear violet color, form brown ppt. (manganus oxide

Alkaline Kmno4: acid + Na2CO3 sol. +KMNO4

Fruity or ripe apple odor

- Esterfication :

ethOH +acid + Conc. H2SO4 heat then pour it onto H2O

Citric acid Tartaric acidEff. And yellow stain Eff. And charring Conc. H2SO4: (hot)Discoloration of violet color anf form white ppt.

- Denges: acid+ H2O+ denges reagent boiling (without cooling) + KMNO4

Phthalic acid Benzoic acidUnstable pink color - Phthaline test:

Phenol+ acid +Conc. H2SO4 heat then pour it onto 10% NaOH

Reddish brown color give green flourescence if dilute it with water

- Flourescence;Acid + resercinol+ Conc. H2SO4 heat then pour it onto 10% NaOH

Salicylic acid

Esterfication:methanol+ saliucylic acid+ Conc H2SO4heat then pour it onto 10 ml of H2O → vicks odor of winter green oil due to methyl salicylate formation.

Formaldehyde:Formaldehyde+ salicylic acid + Conc. H2SO4→ crimson red color on the wall.

Phthaline test:Salicylic acid + phthalic unhydride +Conc. H2SO4 heat then pour it onto 10 ml of 10% NaOH→ unstable pink color

IR location

COOH stretching band at 1710 cm-1