soaps Acetylsalicylic acid Acetic acid water Carboxylic acids Aliphatic carboxylic acids Formic acid pungent true ID: 225468
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Slide1
Benzoic acid is used for foods while benzoin resin is used in cosmetics, lotions and
soaps
Acetylsalicylic acid
Acetic acid +waterSlide2
Carboxylic acids
Aliphatic carboxylic acidsFormic acid pungent
true liqid mobilyAcetic acid colorless
vinegar
Tartaric acid solid crystalline Citric acid yellowish white odorlessSlide3
Aromatic carboxylic acids
Benzoic acid solid crystalline,
yellowish white odorlessSalicylic acid
Phthalic
acid solid flaky ,yellowish white odorlessSlide4
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 Slide5
Color flame:No change with allOdor:
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.Slide6
Acid base testAcidity 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
Slide7
Conc. HCLAcidity test
L.PH2O
acidsReppt
.
effervescentChange blue to red
Miscible
Formic
Acetic
Change blue to red
soluble
tartaric
citric
Not done
Insoluble in H2O ,
dil
HCL but soluble in 10%NaOH
benzoic
phthalic
salicylic
All strong acidSlide8
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.Slide9
30%NaOH:The same result of soda lime FeCL
3:No reaction with all.Conc. H
2SO4: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 reactionSlide10
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.Slide11
Differentiation tests
Acetic acid
Formic acid-Turbidity or whit ppt. (Hg2CL2)HgCL2:
HgCL2+acid (wait 5 min)-
Disappear violet color, form brown ppt. (manganus oxideAlkaline Kmno4: acid + Na2CO3 sol. +KMNO4
Fruity
or ripe apple odor
-
Esterfication
:
ethOH
+acid + Conc. H2SO4 heat then pour it onto H2OSlide12
Citric acid
Tartaric acidEff. And yellow stain
Eff. And charringConc. H2SO4: (hot)
Discoloration of violet color anf form white ppt.
-Denges: acid+ H2O+ denges reagent boiling (without cooling) + KMNO4
Phthalic
acid
Benzoic acid
Unstable
pink color
-
Phthaline
test:
Phenol+ acid +Conc. H2SO4 heat then pour it onto 10%
NaOHReddish brown color give green flourescence if dilute it with water
-Flourescence;Acid +
resercinol
+ Conc. H2SO4 heat then pour it onto 10%
NaOHSlide13
Salicylic acidEsterfication:
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 Slide14
IR locationCOOH stretching band at 1710 cm-1