Chemical Properties
colourless liquid with an acrid odour
Uses
An antibacterial agent.
Uses
Usually used in preparing monodispersed poly (N-isopropylacryamide) (PNIPAM)/AAc microgels.And also used primarily as an intermediate in the production of acrylates.
Uses
In the manufacture of plastics.
General Description
Acrylic acid is a colorless liquid with a distinctive acrid odor. Flash point 130°F. Boiling point 286°F. Freezing point 53°F. Corrosive to metals and tissue. Prolonged exposure to fire or heat can cause polymerization. If polymerization takes place in a closed container, violent rupture may occur. The inhibitor (usually hydroquinone) greatly reduces the tendency to polymerize.
Reactivity Profile
ACRYLIC ACID may polymerize violently especially when the frozen acid is partially thawed (freezing point 12°C or 53°F). Frozen acid should be melted at room temperature and the process should be well stirred. Do not use heat during the melting process [Kirk-Othmer, 3rd ed., Vol. 1, 1978, p. 330]. Corrodes iron and steel and polymerization may occur on contact with iron salts. The uninhibited acid polymerizes exothermically at ambient temperature and explodes if confined. The inhibitor (usually hydroquinone) greatly reduces the tendency to polymerize. Explosive polymerization can also occur with strong bases, amines, ammonia, oleum, chlorosulfonic acid, and peroxides. Mixing with 2-aminoethanol, 28% ammonium hydroxide, ethylenediamine or ethyleneimine in a closed container causes an increase in temperature and pressure. Can react violently with oxidizing reagents and strong bases [Bretherick, 5th ed., 1995, p. 419].
Air & Water Reactions
Flammable. Soluble in water. The presence of water, due to different solubilities of the acid and inhibitor (partitioning one from the other), may initiate polymerization.
Health Hazard
May burn skin or eyes upon short contact. INHALATION: eye and nasal irritation and lacrimation. INGESTION: may cause severe damage to the gastrointestinal tract.
Potential Exposure
Acrylic acid is chiefly used in manufacture of plastics, acrylates, polyacrylic acids, polymer, and resins; as a monomer in the manufacture of acrylic resins and plastic products, leather treatment, and paper coatings. Also, it is used as a tackifier and flocculant.
First aid
If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. If victim is conscious, administer water or milk. Do not induce vomiting.
Shipping
UN2218 Acrylic acid, stabilized, Hazard class: 8; Labels: 8-Corrosive material, 3-Flammable liquid
Incompatibilities
May form explosive mixture with air. Light, heat, and peroxides can cause polymerization. Use MEHQ (monomethyl ether of hydroquinone) as an inhibitor. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. Incompatible with sulfuric acid, caustics, ammonia, amines, isocyanates, alkylene oxides; epichlorohydrin, toluene diamine, oleum, pyridine, methyl pyridine, n-methyl pyrrolidone, 2-methyl-6-ethyl aniline, aniline, ethylene diamine, ethyleneimine, and 2aminoethanol. Severely corrodes carbon steel and iron; attacks other metals. May accumulate static electrical charges and may cause ignition of its vapors.
Description
Acrylic acid (IUPAC: prop-2-enoic acid) is an organic compound with the formula CH2=CHCO2H. It is the simplest unsaturated carboxylic acid, consisting of a vinyl group connected directly to a carboxylic acid terminus. This colorless liquid has a characteristic acrid or tart smell. It is miscible with water, alcohols, ethers, and chloroform. More than one billion kilograms are produced annually.
Waste Disposal
Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal. Incineration. 100 500 ppm potassium permanganate will degrade acrylic acid to a hydroxy acid which can be disposed of at a sewage treatment.
Definition
An unsaturated liquid carboxylic acid with a pungent odor.
The acid and its esters are used to make
ACRYLIC RESINS.
Preparation
There are three routes to acrylic acid which have commercial significance;
they are based on propylene, acetylene and ethylene respectively. At the
present time, most acrylic acid is produced via the propylene route.
(i) Propylene route. This route involves the two-stage oxidation of propylene:
A mixture of propylene, air and steam is fed into a reactor containing a
catalyst at about 320??C to give acrolein. This intermediate is not isolated but
is passed directly to a second reactor, also containing a catalyst, at about
280??C. The effluent is cooled by contact with cold aqueous acrylic acid.
Acrylic acid is extracted from the solution with a solvent and then separated
by distillation. Because of the ready availability of low cost propylene, this
route has become the preferred route for the production of acrylic acid.
(ii) Acetylene route. This route involves the reaction of acetylene, carbon
monoxide and water:
In one process, the reaction is conducted in solution in tetrahydrofuran at
about 200??C and 6-20 MPa (60--200 atmospheres). Nickel bromide is used as
catalyst. The solution of acrylic acid in tetrahydrofuran, after separation of
the unconverted acetylene and carbon monoxide in a degassing column,
passes to a distillation tower where tetrahydrofuran is taken overhead and
acrylic acid is the bottom product. The reaction between acetylene, carbon
monoxide and water may also be carried out by using nickel carbonyl as the
source of carbon monoxide. In this case, milder reaction conditions are
possible. Owing to the high cost of acetylene, this route is now of little
commercial importance.
(iii) Ethylene route. This route consists of the following sequence:
The addition of
hydrogen cyanide to ethylene oxide takes place at 55-60??C in the presence of
a basic catalyst such as diethylamine. The reaction is exothermic and is
carried out in solution to facilitate control; the solvent is conveniently
ethylene cyanohydrin. The reaction mixture is neutralized and ethylene
cyanohydrin is separated by distillation. The second stage of the synthesis
involves the dehydration and hydrolysis of ethylene cyanohydrin; these
reactions are carried out in one step by heating the cyanohydrin with
aqueous sulphuric acid at about 175??C. (It is possible, of course, that the intermediate in this conversion may be acrylonitrile, as shown, or P-hydroxypropionic acid or both.) At one time this was the standard route for the
preparation of acrylic acid but it has been largely displaced by the more
economical propylene route.
Production Methods
Acrylic acid is produced from propene which is a by product of ethylene and gasoline production. CH2=CHCH3 + 1.5 O2→ CH2=CHCO2H + H2O Because acrylic acid and its esters have long been valued commercially, many other methods have been developed but most have been abandoned for economic or environmental reasons. An early method was the hydrocarboxylation of acetylene ("Reppe chemistry") : HCCH + CO + H2O → CH2=CHCO2H This method requires nickel carbonyl and high pressures of carbon monoxide. It was once manufactured by the hydrolysis of acrylonitrile which is derived from propene by ammoxidation, but was abandoned because the method cogenerates ammonium derivatives. Other now abandoned precursors to acrylic acid include ethenone and ethylene cyanohydrin.
Fire Hazard
Combustible liquid; flash point (closed cup)
54°C (130°F), (open cup) 68°C (155°F);
vapor pressure 31 torr at 25°C (77°F); vapor
density 2.5 (air=1); autoignition temperature 360°C (680°F). Vapors of acrylic acid
form explosive mixtures with air within the
range 2.9–8.0% by volume in air. Fireextinguishing agent: water spray, “alcohol”
foam, dry chemical, or CO2; use a water
spray to flush and dilute the spill and to disperse the vapors.
Acrylic acid may readily polymerize at
ambient temperature. Polymerization may
be inhibited with 200 ppm of hydroquinone
monomethyl ether (Aldrich 2006). In the
presence of a catalyst or at an elevated temperature, the polymerization rate may accelerate, causing an explosion. The reactions of
acrylic acid with amines, imines, and oleum
are exothermic but not violent. Acrylic acid
should be stored below its melting point with
a trace quantity of polymerization inhibitor.
Its reactions with strong oxidizing substances
can be violent.
Flammability and Explosibility
Flammable
Safety
Acrylic acid is severely irritating and corrosive to the skin and the respiratory tract. Eye contact can result in severe and irreversible injury. Low exposure will cause minimal or no health effects, while high exposure could result in pulmonary edema. The LD50 is 340 mg/kg (rat, oral).
Environmental Fate
Acrylic acid is corrosive, and its toxicity occurs at the site of
contact.
Purification Methods
It can be purified by steam distillation, or vacuum distillation through a column packed with copper gauze to inhibit polymerisation. (This treatment also removes inhibitors such as methylene blue that may be present.) Azeotropic distillation of the water with *benzene converts aqueous acrylic acid to the anhydrous material. [Beilstein 2 H 397, 2 I 186, 2 II 383, 2 III 1215, 2 IV 1455.]
Substituents
As a substituent acrylic acid can be found as an acyl group or a carboxyalkyl group depending on the removal of the group from the molecule. More specifically these are :
The acryloyl group, with the removal of the -OH from carbon-1.
The 2-carboxy ethenyl group, with the removal of a -H from carbon-3. This substituent group is found in chlorophyll..
Toxicity evaluation
Acrylic acid’s large-scale use and production results in its release
into the environment. The most likely route of exposure is
inhalation because acrylic acid has a low vapor pressure. The
miscibility of acrylic acid in water combined with its low vapor
pressure prevent it from accumulating in the soil. Acrylic acid
that is emitted into the atmosphere is degraded photochemically
by reaction with hydroxyl radicals. There is no potential
for long-range atmospheric transport of acrylic acid because it
has an atmospheric lifetime of 1 month.
Toxics Screening Level
The current ITSL for acrylic acid (1 μg/m3) was originally established on 4/1/94. The averaging time (AT) assigned at that time was 24 hours.
