Acetate is the
ester that an organic group replaces a hydrogen atom in -OH group of acetic acid
through reaction (typically condensation) with alcohols. Condensation is the
reaction in which two molecules having -OH groups are joined with eliminating a
water molecule from their -OH groups. They are produced by esterification reaction from acetic acid and the corresponding alcohol in the presence of strong acids like sulfuric acid. This reaction is reversible and acetate
can be hydrolyzed back into
alcohol and acetic acid in the presence of strong bases or strong acid, especially at elevated temperature.
The term acetate is also for the salt that
one or more of the hydrogen atoms of acetic acid are replaced by one or more
cations of the base, resulting in a compound containing the negative organic ion
of CH3COO-. Lower
acetate is a non-polar to weak polar aprotic solvent which have some solubility
portion in water. Its miscibility with water gets higher at elevated temperature.
Higher acetates have a
low
solubility in water and used as extraction solvents for fine chemicals
particularly for certain antibiotics. Organic acetates are
good solvents for a broad range of resins as they are miscible with almost all
common organic liquids. Due to their powerful solvency, high volatility and mild
odor, acetates are widely used as solvents for paints, coatings, adhesives, cellulose, plastics, fats,
wood stains. Additionally ether acetates series are also widely used as solvents. This surfactant-like structure provides the compatibility between water and a
number of organic solvents, and the ability to couple unlike phases. The main
products include ethyleneglycol
monoethyl ether acetate, ethyleneglycol monobutyl ether acetate,
and propyleneglycol monomethyl ether acetate.
Aromatic acetates
such as benzyl acetate are also useful solvent. Benzyl acetate has jasmine
like odor. Isoamyl acetate has a similar smell to both banana and pear. Acetates have characteristic fruity odor. They are used as component of perfumes
and flavorings.
They are used as chemical intermediate to manufacture pharmaceuticals, synthetic
flavorings, cleaners, and other organic compounds.
Acetate
|
FORMULA |
CAS
RN
|
B.P
C
|
Methyl acetate |
CH3COOCH3 |
79-20-9 |
57 - 58 |
Ethyl acetate |
CH3COOC2H5 |
141-78-6 |
76.5 - 77.5 |
Propyl acetate |
CH3COOCH2CH2CH3 |
109-60-4 |
101 - 102
|
Isopropyl acetate |
CH3COOCH(CH3)2 |
108-21-4 |
89 |
Butyl
acetate
|
CH3COO(CH2)3CH3 |
123-86-4
|
124 - 126 |
isobutyl acetate |
CH3COOCH2CH(CH3)2 |
110-19-0 |
115 - 117 |
Amyl acetate
|
CH3COO(CH2)4CH3 |
628-63-7
|
149 |
Isoamyl acetate |
CH3COOCH2CH2CH(CH3)2 |
123-92-2 |
142 |
Hexyl
acetate
|
CH3COO(CH2)5CH3 |
142-92-7
|
170 - 172 |
Heptyl acetate
|
CH3COO(CH2)6CH3 |
112-06-1
|
192 - 193 |
Octyl acetate |
CH3COO(CH2)7CH3 |
112-14-1 |
205 - 211 |
Nonanyl acetate |
CH3COO(CH2)8CH3 |
143-13-5 |
212 |
Decyl acetate
|
CH3COO(CH2)9CH3 |
112-17-4
|
272 |
Undecyl acetate |
CH3COO(CH2)10CH3 |
112-19-6 |
269 - 271 |
Lauryl acetate
|
CH3COO(CH2)11CH3 |
112-66-3
|
265 |
Tridecyl acetate |
CH3COO(CH2)12CH3 |
1072-33-9 |
|
Myristyl acetate |
CH3COO(CH2)13CH3 |
638-59-5 |
|
Pentadecyl acetate
|
CH3COO(CH2)14CH3 |
629-58-3
|
|
Cetyl acetate |
CH3COO(CH2)15CH3 |
629-70-9
|
|
Heptadecyl acetate |
CH3COO(CH2)16CH3 |
822-20-8 |
|
Stearyl acetate
|
CH3COO(CH2)17CH3 |
822-23-1
|
|
Behenyl
acetate
|
CH3COO(CH2)21CH3 |
822-26-4
|
|
Hexacosyl acetate
|
C28H56O2 |
822-32-2
|
|
Triacontyl
acetate
|
C32H64O2 |
41755-58-2
|
|
Benzyl acetate |
CH3COOCH2C6H5 |
140-11-4 |
213 - 214 |
Bornyl acetate |
C12H20O2 |
76-49-3 |
228 - 231 |
Isobornyl acetate |
C12H20O2 |
125-12-2 |
229 - 233 |
Cyclohexyl acetate |
CH3COOC6H11 |
622-45-7 |
172 - 173 |
|
Acetic acid is
the simplest carboxylic acid next to formic acid in which a single hydrogen atom
is attached to the carboxyl group. If a methyl group is attached to the carboxyl
group, the compound is acetic acid. Acetic acid is a clear, corrosive, flammable
liquid; melting point 16.6 C, boiling point 118 C. Pure acetic acid freezes in
ice-like crystal form. So pure acetic acid is called glacial acetic acid, which
contains 99.5 - 100.5 % w/w. It is the two-carbon carboxylic acid, and a
systematic name is ethanoic acid. It is completely miscible with water, ethyl
alcohol and ether, but is insoluble in carbon disulfide. It is a characteristic
component of vinegar and an important biochemical intermediate in the form of
acetylcoenzyme A, mostly. Most commercial production of virgin synthetic acetic
acid is based on methanol carbonylation. Significant volumes of acetic acid are
recovered in cellulose acetate operations and lesser quantities during
production of polyvinyl alcohol and butyral, peracetic acid, ethylene-vinyl
alcohol and acetaminophen and aspirin. Capacity utilization is likely to remain
high for the next few years because of good demand for purified terephthalic
acid and vinyl acetate monomer.
Vinyl acetate
monomer
The largest
consumption of acetic acid is as a raw material to produce vinyl acetate by
reaction with ethylene and oxygen or with acetylene in the presence of
palladium catalyst. Vinyl acetate is polymerized to polyvinyl acetate by itself
and to other copolymers with other monomers. Acetate polymers are important
resins used in paints, adhesives, plastics and textile finishes.
Acetic
anhydride
The next
largest consumption of acetic acid is to produce acetic anhydride by
condensation reaction of two acetic acid molecules. This chemical is principally
used in the manufacture of cellulose acetate having the application as a base
for magnetic tape and in the manufacture of textile fibres. Also, it is heated
with salicylic acid to produce acetylsalicylic acid (aspirin). It is also used
in the manufacture of pigments, dyes, cellulose and pesticides etc.
Solvent
Acetic acid
is used as a solvent in the production of terephthalic acid from p-xylene.
Terephthalic acid is the raw material for polyester fiber. Terephthalic acid has
become a more important raw material for non-fiber field, PET-bottle, PET-film
and engineering plastics and as poultry feed additives.
Esters
Considerable
quantities of acetic acid are used to manufacture esters such as ethyl and butyl
acetate. Acetate esters demonstrate good solvency for many natural and synthetic
resins. They are general purpose solvents which are applied commonly in lacquer
thinners, wood lacquers and a wide variety of coatings, plasticizer and
pharmaceutical fields.
Chloroacetic
acid
The stronger
acid (chloroacetic acid) is manufactured from acetic acid by reaction with
chlorine. Chloroacetic acid reacts with alkali cellulose to produce
carboxymethylcellulose (CMC). Chloroacetic acid is the parent material for the
production of a series of phenoxy herbicides such as 2,4-dichlorophenoxyacetic
acid and 2,4,5-trichlorophenoxyacetic acid.
Acetic acid
is used as an acidulant in a wide range of applications from eletroplating to
textiles finishing operation. It is used in the manufacture of materials used in
the pharmaceuticals, foods, cosmetics and colorant chemical fields including
sorbic acid, dyestuffs and pigments, vitamins, antibiotics, rubber chemicals and
flavor & fragrance.
|