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Acetic acid +water. Acetylsalicylic acid. Benzoic acid is used for foods while benzoin resin is used in cosmetics, lotions and soaps. Carboxylic acids. Aliphatic carboxylic acids. Formic acid pungent - PowerPoint PPT Presentation
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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