CAS Number 75-21-8
·
Empirical Formula (Hill Notation) C2H4O
·
Molecular Weight 44.05
·
Beilstein Registry Number 102378
Ethylene oxide, properly called oxirane by IUPAC, is an organic
compound with
the formula C2H4O. It is a cyclic ether, consisting of an alkane with an oxygen atom
bonded to two carbon atoms of the alkane, forming a ring. Ethylene oxide is a
colorless and flammable gas at room temperature, with a faintly sweet odor; it
is the simplest epoxide: a three-membered ring consisting of
one oxygen atom and two carbon atoms.
Applications
Ethylene oxide is one of the most important raw
materials used in large-scale chemical production. Most ethylene oxide is used
for synthesis of ethylene glycols, including
diethylene glycol and triethylene glycol, that accounts for up to 75% of global
consumption. Other important products include ethylene glycol ethers,
ethanolamines and ethoxylates. Among glycols, ethylene glycol is used as antifreeze, in the production
of polyester and polyethylene
terephthalate (PET – raw material for plastic bottles),
liquid coolants and solvents.
|
Sector
|
Demand share (%)
|
|
7
|
|
|
Oilfield chemicals
|
10
|
|
25
|
|
|
35
|
|
|
Personal
care
|
10
|
|
8
|
|
|
Others
|
5
|
|
Total
[2009]
|
5.2
mt
|
Polyethyleneglycols are used in perfumes, cosmetics,
pharmaceuticals, lubricants, paint thinners and plasticizers. Ethylene glycol
ethers are part of brake fluids, detergents, solvents, lacquers and paints.
Other products of ethylene oxide. Ethanolamines are used in the manufacture of
soap and detergents and for purification of natural gas. Ethoxylates are reaction
products of ethylene oxide with higher alcohols, acids or amines. They are used
in the manufacture of detergents, surfactants, emulsifiers and dispersants.[84]
Whereas synthesis of ethylene glycols is the major
application of ethylene oxide, its percentage varies greatly depending on the region:
from 44% in the Western Europe, 63% in Japan and 73% in North America to 90% in the
rest of Asia and 99% in Africa.[85]
Production of ethylene glycol
Ethylene glycol is industrially produced by
non-catalytic hydration of ethylene oxide at a temperature of 200 °C and a
pressure of 1.5–2 MPa:[86]
(CH2CH2)O
+ H2O → HOCH2CH2OH
By-products of the reaction are diethylene glycol,
triethylene glycol and polyglycols with the total of about 10%, which are
separated from the ethylene glycol by distillation at reduced pressure.[87]
Another synthesis method is the reaction of ethylene
oxide and CO2 (temperature 80–120 °C and pressure of 5.2
MPa) yielding ethylene carbonate and its subsequent hydrolysis with decarboxylation:[86]
Modern technologies of
production of ethylene glycol include the following.[88] Shell OMEGA technology
(Only Mono-Ethylene Glycol Advantage) is a two-step synthesis of ethylene
carbonate using a phosphonium halide
as a catalyst. The glycol yield is 99–99.5%, with other glycols practically
absent. The main advantage of the process is production of pure ethylene glycol
without the need for further purification. The first commercial plant which
uses this method was opened in 2008 in South Korea.[89] Dow METEOR (Most Effective
Technology for Ethylene Oxide Reactions) is an integrated technology for
producing ethylene oxide and its subsequent hydrolysis into ethylene glycol.
The glycol yield is 90–93%. The main advantage of the process is relative
simplicity, using fewer stages and less equipment.
Production of glycol ethers
The major industrial esters of mono-, di- and
triethylene glycols are methyl, ethyl and normal butyl ethers, as well as their
acetates and phthalates. The synthesis involves reaction of the
appropriate alcohol with ethylene oxide:[90]
(CH2CH2)O
+ ROH → HOCH2CH2OR
(CH2CH2)O
+ HOCH2CH2OR → HOCH2CH2OCH2CH2OR
(CH2CH2)O
+ HOCH2CH2OCH2CH2OR → HOCH2CH2OCH2CH2OCH2CH2OR
The reaction of monoesters with an acid or its
anhydride leads to the formation of the esters:
CH3COOH
+ HOCH2CH2OR → ROCH2CH2OCOCH3 +
H2O
Production of ethanolamines
In the industry, ethanolamines (mono-, di- and triethanolamines)
are produced by reacting ammonia and ethylene
oxide in anhydrous medium at a temperature of 40–70 °C and pressure of
1.5–3.5 MPa:[91]
(CH2CH2)O
+ NH3 → HOCH2CH2NH2
2
(CH2CH2)O + NH3 → (HOCH2CH2)2NH
3
(CH2CH2)O + NH3 → (HOCH2CH2)3N
All three ethanolamines are produced in the process,
while ammonia and part of methylamine are recycled. The final products are
separated by vacuum distillation. Hydroxyalkylamines
are produced in a similar process:
(CH2CH2)O
+ RNH2 → HOCH2CH2NHR
2
(CH2CH2)O + RNH2 → (HOCH2CH2)2NR
Monosubstituted products are formed by reacting a
large excess of amine with ethylene oxide in presence of water and at a
temperature below 100 °C. Disubstituted products are obtained with a small
excess of ethylene oxide, at a temperature of 120–140 °C and a pressure of
0.3–0.5 MPa.[92][93]
Production of ethoxylates
Industrial production of ethoxylates is realized by
a direct reaction of higher alcohols, acids or amines with ethylene oxide in
the presence of an alkaline catalyst at a temperature of 120–180 °C. Modern
plants producing ethoxylates are usually based on the BUSS LOOP reactors
technology,[94] which is based on a three-stage
continuous process. In the first stage, the initiator or catalyst of the
reaction and the feedstock are fed into the container, where they are mixed,
heated and vacuum dried. Then reaction is carried out in a special insulated
reactor in an inert atmosphere (nitrogen) to prevent a possible explosion of
ethylene oxide. Finally, the reaction mixture is neutralized, degassed and
purified.[95]
Production of acrylonitrile
Currently, most acrylonitrile (90% in 2008) is produced by the
SOHIO method, which is based on the catalytic oxidation of propylene in the
presence of ammonia and bismuth phosphomolybdate. However, until 1960 a key
production process was addition of hydrogen cyanide to ethylene
oxide, followed by dehydration of the resulting cyanohydrin:[96] [97]
Addition of hydrocyanic acid to ethylene oxide is
carried out in the presence of a catalyst (sodium hydroxide and diethylamine), and dehydration of cyanohydrin occurs
in the gas phase upon the catalytic action of aluminium oxide.[98]
Non-industrial uses
The direct use of ethylene oxide accounts for only
0.05% (2004 data) of its global production.[76] Ethylene oxide
is used as a sterilizing agent, disinfecting agent and fumigant as a mixture
with carbon dioxide (8.5–80% of ethylene oxide), nitrogen or dichlorodifluoromethane (12% ethylene oxide). It is applied for gas-phase
sterilization of medical equipment and instruments, packaging materials and
clothing, surgical and scientific equipment;[76] for processing
of storage facilities (tobacco, packages of grain, sacks of rice, etc.),
clothing, furs and valuable documents.[99]
Healthcare sterilant
Ethylene oxide is one of the most commonly used
sterilization methods in the healthcare industry because of its non-damaging
effects for delicate instruments and devices that require sterilization, and
for its wide range of material compatibility.[100] It is used for
instruments that cannot tolerate heat, moisture or abrasive chemicals, such as
electronics, optical equipment, paper, rubber and plastics.[101] It was
developed in the 1940s as a sterilant by the US military, and its use as a
medical sterilant dates to the late 1950s, when the McDonald process was
patented for medical devices.[102] The Anprolene system was patented in the 1960s[103] by Andersen Products,[104] and it remains
the most commonly used system in several niche markets, notably the veterinary
market and some international markets.[105] It relies on
the use of a flexible sterilization chamber and an EtO cartridge for small
volume sterilization, and where environmental and/or portability considerations
dictate the use of a low dose. It is therefore referred to as the
"flexible chamber sterilization" method, or the "gas diffusion
sterilization" method. In the United States, the operation of EtO
sterilization is overseen by the EPA through the National Emission Standard for Hazardous Air
Pollutants.[106]
Niche uses
Ethylene oxide is used as an accelerator of
maturation of tobacco leaves and fungicide.[99] Ethylene oxide
is also used as a main component of thermobaric weapons (fuel-air
explosives).
PRICE
$131.10/KG OR $59.59/IB
For more information:
mobile: +2348039721941
contact person: emeaba uche
e-mail: emeabau@yahoo.com
No comments:
Post a Comment