Acrolein
Overview
 
Acrolein is the simplest unsaturated
Saturation (chemistry)
In chemistry, saturation has six different meanings, all based on reaching a maximum capacity...

 aldehyde
Aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....

. It is produced widely but is most often immediately reacted with other products due to its instability and toxicity. It has a piercing, disagreeable, acrid smell; the smell of burnt fat (as when cooking oil
Cooking oil
Cooking oil is purified fat of plant origin, which is usually liquid at room temperature ....

 is heated to its smoke point
Smoke point
The smoke point generally refers to the temperature at which a cooking fat or oil begins to break down to glycerol and free fatty acids, and produce bluish smoke. The glycerol is then further broken down to acrolein which is a component of the smoke. It is the presence of the acrolein that causes...

) is caused by glycerol
Glycerol
Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...

 in the burning fat breaking down into acrolein.
Acrolein is prepared industrially by oxidation of propene. Efforts are under way to use propane
Propane
Propane is a three-carbon alkane with the molecular formula , normally a gas, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used as a fuel for engines, oxy-gas torches, barbecues, portable stoves, and residential central...

 as feedstock for the synthesis; however, this is more difficult.
Several million tons of acrolein are produced each year.

When glycerol
Glycerol
Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...

 is heated to 280 °C, it decomposes into acrolein.
Acrolein may also be produced on lab scale by the reaction of potassium bisulfate on glycerol (glycerine).
Acrolein is used in the preparation of polyester resin
Polyester resin
Polyester resins are unsaturated resins formed by the reaction of dibasic organic acids and polyhydric alcohols. Polyester resins are used in sheet moulding compound, bulk moulding compound and the toner of laser printers...

, polyurethane
Polyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...

, propylene glycol
Propylene glycol
Propylene glycol, also called 1,2-propanediol or propane-1,2-diol, is an organic compound with formula C3H8O2 or HO-CH2-CHOH-CH3...

, acrylic acid
Acrylic acid
Acrylic 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,...

, acrylonitrile
Acrylonitrile
Acrylonitrile is the chemical compound with the formula C3H3N. This pungent-smelling colorless liquid often appears yellow due to impurities. It is an important monomer for the manufacture of useful plastics. In terms of its molecular structure, it consists of a vinyl group linked to a nitrile...

, and glycerol
Glycerol
Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...

.
Acrolein tends to polymerize when left at room temperature, leaving a gummy yellowish residue with a putrid odor.
Encyclopedia
Acrolein is the simplest unsaturated
Saturation (chemistry)
In chemistry, saturation has six different meanings, all based on reaching a maximum capacity...

 aldehyde
Aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....

. It is produced widely but is most often immediately reacted with other products due to its instability and toxicity. It has a piercing, disagreeable, acrid smell; the smell of burnt fat (as when cooking oil
Cooking oil
Cooking oil is purified fat of plant origin, which is usually liquid at room temperature ....

 is heated to its smoke point
Smoke point
The smoke point generally refers to the temperature at which a cooking fat or oil begins to break down to glycerol and free fatty acids, and produce bluish smoke. The glycerol is then further broken down to acrolein which is a component of the smoke. It is the presence of the acrolein that causes...

) is caused by glycerol
Glycerol
Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...

 in the burning fat breaking down into acrolein.

Synthesis

Acrolein is prepared industrially by oxidation of propene. Efforts are under way to use propane
Propane
Propane is a three-carbon alkane with the molecular formula , normally a gas, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used as a fuel for engines, oxy-gas torches, barbecues, portable stoves, and residential central...

 as feedstock for the synthesis; however, this is more difficult.
Several million tons of acrolein are produced each year.

When glycerol
Glycerol
Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...

 is heated to 280 °C, it decomposes into acrolein.
Acrolein may also be produced on lab scale by the reaction of potassium bisulfate on glycerol (glycerine).

Uses

Acrolein is used in the preparation of polyester resin
Polyester resin
Polyester resins are unsaturated resins formed by the reaction of dibasic organic acids and polyhydric alcohols. Polyester resins are used in sheet moulding compound, bulk moulding compound and the toner of laser printers...

, polyurethane
Polyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...

, propylene glycol
Propylene glycol
Propylene glycol, also called 1,2-propanediol or propane-1,2-diol, is an organic compound with formula C3H8O2 or HO-CH2-CHOH-CH3...

, acrylic acid
Acrylic acid
Acrylic 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,...

, acrylonitrile
Acrylonitrile
Acrylonitrile is the chemical compound with the formula C3H3N. This pungent-smelling colorless liquid often appears yellow due to impurities. It is an important monomer for the manufacture of useful plastics. In terms of its molecular structure, it consists of a vinyl group linked to a nitrile...

, and glycerol
Glycerol
Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...

.
Acrolein tends to polymerize when left at room temperature, leaving a gummy yellowish residue with a putrid odor. It is also thought to be an intermediate in the Skraup synthesis
Skraup reaction
The Skraup synthesis is a chemical reaction used to synthesize quinolines. It is named after the Czech chemist Zdenko Hans Skraup . In the archetypal Skraup, aniline is heated with sulfuric acid, glycerol, and an oxidizing agent, like nitrobenzene to yield quinoline.In this example, nitrobenzene...

 of quinolines, but is rarely used as such due to its instability.
Acrolein is sometimes used as a fixative in preparation of biological specimens for electron microscopy. It is also used as a contact herbicide to control submersed and floating weeds, as well as algae, in irrigation canals.

Health risks

Acrolein is a severe pulmonary irritant
Pulmonary agent
A pulmonary agent is a chemical weapon agent designed to impede a victim's ability to breathe. They operate by causing a build-up of fluids in the lungs which then leads to...

 and lachrymatory agent
Lachrymatory agent
Tear gas, formally known as a lachrymatory agent or lachrymator , is a non-lethal chemical weapon that stimulates the corneal nerves in the eyes to cause tears, pain, and even blindness...

. It was used as a chemical weapon during World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. It is, however, not outlawed by the Chemical Weapons Convention
Chemical Weapons Convention
The Chemical Weapons Convention is an arms control agreement which outlaws the production, stockpiling and use of chemical weapons. Its full name is the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction...

.
Dermal exposure of acrolein to the eyes (0.3ppm in air) can cause severe irritation. Acrolein is not a suspected human
Human
Humans are the only living species in the Homo genus...

 carcinogen
Carcinogen
A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes...

; no studies have been conducted on the carcinogenic effects of acrolein on humans, but studies on rats have shown an increase in cancerous tumors from ingestion. In October 2006, researchers found connections between acrolein in the smoke from tobacco cigarettes
Tobacco smoking
Tobacco smoking is the practice where tobacco is burned and the resulting smoke is inhaled. The practice may have begun as early as 5000–3000 BCE. Tobacco was introduced to Eurasia in the late 16th century where it followed common trade routes...

 and the risk of lung cancer
Lung cancer
Lung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung in a process called metastasis into nearby tissue and, eventually, into other parts of the body. Most cancers that start in lung, known as primary...

. Furthermore, acrolein is a possible metabolite of cyclophosphamide
Cyclophosphamide
Cyclophosphamide , also known as cytophosphane, is a nitrogen mustard alkylating agent, from the oxazophorines group....

, a cytotoxic chemotherapy
Chemotherapy
Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....

 agent, and results in hemorrhagic cystitis
Hemorrhagic cystitis
Hemorrhagic cystitis or Haemorrhagic cystitis is diffuse inflammation of the bladder leading to dysuria, hematuria, and hemorrhage. The disease can occur as a complication of cyclophosphamide, ifosfamide and radiation therapy...

. N-acetylcysteine or mesna
Mesna
Mesna is an organosulfur compound. It is used in cancer chemotherapy involving cyclophosphamide and ifosfamide as an adjuvant. It is marketed by Baxter as Uromitexan and Mesnex...

 are used to counteract the acrolein.

Due to its ability to damage myelin
Myelin
Myelin is a dielectric material that forms a layer, the myelin sheath, usually around only the axon of a neuron. It is essential for the proper functioning of the nervous system. Myelin is an outgrowth of a type of glial cell. The production of the myelin sheath is called myelination...

 nerve sheaths, acrolein may be a factor in the development of multiple sclerosis
Multiple sclerosis
Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...

. The antihypertensive drug hydralazine
Hydralazine
Hydralazine is a direct-acting smooth muscle relaxant used to treat hypertension by acting as a vasodilator primarily in arteries and arterioles...

, a known scavenger of acrolein, was found to reduce myelin damage and significantly improve behavioral outcomes in a mouse model of multiple sclerosis (experimental autoimmune encephalomyelitis
Experimental autoimmune encephalomyelitis
Experimental autoimmune encephalomyelitis, sometimes Experimental Allergic Encephalomyelitis is an animal model of brain inflammation. It is an inflammatory demyelinating disease of the central nervous system...

).

EPA method 603 is designed to measure acrolein in industrial and municipal wastewater
Wastewater
Wastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations...

 streams.

Acrolein test

Acrolein test is a test for the presence of glycerin or fats
Fats
Fats may refer to:*Fat, a generic term for a class of lipids in biochemistry*Fats Domino, rock and roll pianist*Fats Waller, jazz pianist*Fats Navarro, jazz trumpeter*Singing Fats, master of ceremonies*Obesity...

. A sample is heated with potassium bisulfate, and acrolein is released if the test is positive. When a fat is heated strongly in the presence of a dehydrating agent such as potassium bisulfate , the glycerol portion of the molecule is dehydrated to form the unsaturated aldehyde
Aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....

, acrolein (CH2=CH–CHO), which has the peculiar odor of burnt grease.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK