Acetic acid

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Acetic acid
Acetic acid struct.png
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
NFPA704.png
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[1]
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
  • The eutectic point is -27°C / 71.6% (mol/mol) / 88.3% (kg/kg).

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

Storage

Disposal

See Also

References

  1. SEBASTIANI, E.; LACQUANITI, L. (1967) "Acetic acid-water system thermodynamical correlation of vapor-liquid equilibrium data"
    Chemical Engineering Science 22; pp1155-l162. Pergamon Press Ltd.