Acetic acid

 

Acetic acid

Chemical formula	CH3COOH
Molar Mass(g/mol)	60
Melting Point(°C)	16-17
Boiling Point(°C)	118-119
Density(g/cc)	1.049
Index of refraction	1.371
Solubility in water(g/L)	misc
Immediate Danger to Life and Health	40ppm (inhaled, 100%)
NFPA 704	2 3 0

Uses

• Generically, as an acid which can be produced fairly easily
• Feedstock for acetic anhydride
• Source acid for all acetate compounds
• Pharm: Ear/nose/throat topical application

Natural occurence

Main Article: Vinegar

Acetic acid does occur naturally as a secondary metabolite of acetobacter as it consumes ethanol.

CH₃CH₂OH + O₂

{acetobacter

→

30°C}

CH₃COOH + H₂OΔH=-490kJ

Hazards

• Bronchial & skin irritant

Character

Molar fractions in liquid and vapor at various temperatures

Temperature (°C)	Mol% water in liquid	Mol% water in vapor
100.8	0.865	0.907
101.7	0.755	0.817
102.4	0.675	0.770
103.5	0.5725	0.678
104.2	0.520	0.635
105.6	0440	0.556
107.7	0.305	0.420

Production

Extraction

from vinegar

distillation

• Distill vinegar, preferably at reduced pressure. The water distills over, leaving a proportional increase in concentration. The water bath is important to prevent the possible degradation or oxidation of any acetic acid vapor.

l/l extraction

1. Combine vinegar with diethyl ether
2. Mix well
3. Allow to separate (>90% in the ether layer)
4. decant off the hydrocarbon layer
5. Distill off the hydrocarbons, leaving acetic acid.

Synthesis

From acetates

via sulfuric acid

1. Gather 7 ubm of calcium acetate
2. Gather 4 ubm of sulfuric acid
3. Combine the acetate and acid, producing a solution of acetic acid and calcium sulfate

   Ca(CH₃COO)₂ + H₂SO₄

   {

   →

   otp}

   2 CH₃COOH(l) + CaSO₄(diss.)

4. Distill the solution, precipitating out the calcium sulfate

   CH₃COOH(l) + CaSO₄(dis)

   {

   →

   120°C}

   CH₃COOH(v) + CaSO₄(s)

via hydrochloric acid

As with sulfuric acid, the same reaction can be done with hydrochloric acid producing the more useful calcium chloride as a byproduct.

Ca(CH₃COO)₂ + 2 HCl → CaCl₂ + 2 CH₃COOH

via sodium bisulfate

1. Gather equimolar amounts of anhydrous sodium acetate and sodium bisulfate
2. Grind and thoroughly mix
3. Dry-distill

   NaCH₃COO(s) + NaHSO₄(s)

   {

   →

   heat}

   Na₂SO₄(s) + CH₃COOH(v)

4. The residue is sodium sulfate
5. The distillate is acetic acid

Purification

• Wash with pentane or hexane - immiscible

Testing

Calculation of percent acetic acid

(density of solution)-1 ========================= 0.049

See Also

• Vinegar