Glycerol
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| Glycerol | |
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| Chemical name | Propane-1,2,3-triol |
| Chemical formula | C3H5(OH)3 |
| Molecular mass | 92.09382 g/mol |
| CAS number | [56-81-5] |
| HS number | Crude: 1520.00.00 Pure: 2905.45.00 |
| Density | 1.261 g/cm³ |
| Viscosity | 1.5 Pa.s |
| Melting point | 18 °C (64.4°F) |
| Boiling point | 290 °C (554°F) |
| Food energy | 4.32 kcal/g |
| SMILES | OCC(O)CO |
| Flash Point | 160 C (closed cap) |
| Disclaimer and references | |
Glycerol, also well known as glycerin and glycerine, and less commonly as propane-1,2,3-triol, 1,2,3-propanetriol, 1,2,3-trihydroxypropane, glyceritol, and glycyl alcohol, is a colorless, odorless, hygroscopic, and sweet-tasting viscous liquid. Glycerol is a sugar alcohol and has three hydrophilic alcoholic hydroxyl groups (OH-) that are responsible for its solubility in water. Glycerol has a wide range of applications. Glycerol has a prochiral spatial arrangement of atoms.
Contents |
[edit] Metabolism
When referring to its function in living organisms, the term glycerol is preferred.
Glycerol is a precursor for synthesis of triacylglycerols and of phospholipids in the liver and adipose tissue. When the body uses stored fat as a source of energy, glycerol and fatty acids are released into the bloodstream. The glycerol component can be converted to glucose by the liver and provides energy for cellular metabolism.
Before glycerol can enter enter the pathway of glycolysis or gluconeogenesis (depending on physiological conditions), it must be converted to their intermediate glyceraldehyde 3-phosphate in the following steps:
glycerol glycerol 3-P triose P
kinase dehydrogenase isomerase
glycerol --------> glycerol 3-P <--------------> DHAP <-----------> glyceraldehide 3-P
The enzyme glycerol kinase is present only in the liver. In adipose tissue, glycerol 3-phosphate is obtained from dihydroxyacetone phosphate (DHAP) with the enzyme glycerol 3-phophate dehydrogenase.
[edit] Synthesis
Since glycerol forms the backbone of triglycerides, it is produced on saponification or transesterification. Soap making and biodiesel production are examples of the former and latter, respectively.
[edit] Applications
[edit] Drugs
- Used in medical and pharmaceutical preparations, mainly as a means of improving smoothness, providing lubrication and as a humectant. Also may be used to lower intracranial and intraocular pressures.
- Used as a laxative when introduced into the rectum in suppository or liquid (enema) form; irritates the bowel and induces a hyperosmotic effect.
- Cough syrups, elixirs and expectorants.
- Used as a substitute for alcohol, as a solvent that will create a therapeutic herbal extraction.
[edit] Personal care
- Serves as an emollient, humectant, solvent, and lubricant in personal care products.
- Competes with sorbitol although glycerol has better taste and higher solubility.
- Toothpaste, mouthwashes, skin care products, shaving cream, hair care products and soaps
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- Glycerol is a component of glycerol soap, which is made from denatured alcohol, glycerol, sodium castorate (from castor), sodium cocoate, sodium tallowate, sucrose, water and parfum (fragrance). Sometimes one adds sodium laureth sulfate. This kind of soap is used by people with sensitive, easily irritated skin because it prevents skin dryness with its moisturizing properties. It is possible to make glycerol soap at home.
It was once believed that when used as an emollient, glycerol should never be applied undiluted to the skin. It was thought that the same powerful hygroscopic property that draws moisture out of the air to moisten the skin will draw moisture out of the skin if the glycerol is too concentrated. This in fact has proven to be untrue.
[edit] Foods and beverages
- Serves as humectant, solvent and sweetener, may help preserve foods.
- Solvent for flavors (such as vanilla) and food coloring.
- Humectant and softening agent in candy, cakes and casings for meats and cheeses.
- Manufacture of mono- and di-glycerides for use as emulsifiers
- Used in manufacture of polyglycerol esters going into shortenings and margarine.
- Used as filler in low-fat food products (i.e., cookies).
- Used as thickening agent in liqueurs.
Glycerol has approximately 27 calories per teaspoon and is 60% as sweet as sucrose. Although it has about the same food energy as table sugar, it does not raise blood sugar levels, nor does it feed the bacteria that form plaques and cause dental cavities. Glycerol should not be consumed undiluted, as unhydrated glycerol will draw water from tissues, causing blistering in the mouth and gastric distress. As food additive, glycerol is also known as E number E422.
[edit] Feed
Glycerol is increasingly used in feeding animals.[citation needed]
[edit] Polyether polyols
- One of the major raw materials for the manufacture of polyols for flexible foams, and to a lesser extent rigid polyurethane foams
- Glycerol is the initiator to which propylene oxide/ethylene oxide is added
[edit] Alkyd resins (plastics) and cellophane
- Used in surface coatings and paints
- Used as a softener and plasticizer to impart flexibility, pliability and toughness
- Uses include meat casings, collagen casings (medical applications)and nonmeat packaging
- Plasticizer in cellophane.
[edit] Absolute alcohol
- There is an absolute alcohol production process by dehydration using glycerol.
[edit] Other applications
- Manufacture of paper as a plasticizer, Nitroglycerin, humectant and lubricant
- Used in lubricating, sizing and softening of yarn and fabric
- Used in de-/anti-icing fluids, as in vitrification of blood cells for storage in liquid nitrogen
- Patent applications have been filed for detergent softeners and surfactants based on glycerol (i.e., alkyl glyceryl ethers) instead of quaternary ammonium compounds.
- A way to preserve leaves is to submerge them in a solution of glycerol and water.
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- Use a mixture of one part glycerol to two parts water. Place the mixture in a flat pan, and totally submerge the leaves in a single layer in the liquid. You'll have to weigh them down to keep them submerged. In two to six days, they should have absorbed the liquid and be soft and pliable. Remove them from the pan and wipe off all the liquid with a soft cloth. Done correctly, the leaves will remain soft and pliable indefinitely.
- Can be added to solutions of water and soap to increase that solution's ability to generate soap bubbles that will last a long time.
- Is a component of Shisha, which is a Middle-Eastern tobacco smoked using a hookah
- Used as an antifreeze or a cryoprotectant in cryogenic process.
- Used in fog machine fluids
- Used in hookah tobacco mixtures (called "ma'assel" or "shisha" tobacco), often along with molasses and/or honey.
- Counteracts phenol burns
- Used by some endurance athletes to counteract dehydration by "glycerol loading" before an event.
- Produced as a co-product in bio-diesel synthesis
- Used to preserve bacteria at -80 (prevents lysing of cells).
See also: oleochemicals.
