Polyol

A polyol is an organic compound containing multiple hydroxyl groups. The term "polyol" can have a slightly different meaning in food science and polymer chemistry. A molecule with more than two hydroxyl groups is a polyol, with three – a triol, and with four – a tetrol. By convention, polyols do not refer to compounds that contain other functional groups. Cellulose is a polymer with many alcohol groups, but it is not usually discussed as a polyol.

Sorbitol
Sorbitol, a common sugar alcohol, is a mild sweetener widely used in food industry.

Sugar alcohols

Sugar alcohols, a class of polyols, are commonly obtained by hydrogenation of sugars. They have the formula (CHOH)nH2, where n = 4–6.[1]

Sugar alcohols are added to foods because of their lower caloric content than sugars; however, they are also, in general, less sweet, and are often combined with high-intensity sweeteners. They are also added to chewing gum because they are not broken down by bacteria in the mouth or metabolized to acids, and thus do not contribute to tooth decay. Maltitol, sorbitol, xylitol, erythritol, and isomalt are common sugar alcohols.

Polyol metabolic pathway
The polyol pathway is a process for converting excess glucose. It is implicated in type-II diabetes.

Polymer chemistry

Polyvinyl alcohol has the formula (CH2CHOH)nH2, i.e. it has n alcohol groups where n can be in the thousands.

Glyptal
Structure of an idealized alkyd resin derived from the polyol glycerol (red) and phthalic anhydride.

Low molecular weight polyols are widely used in polymer chemistry, where they function as crosslinking agents. Alkyd resins for example are used in paints and in moulds for casting. They are the dominant resin or "binder" in most commercial "oil-based" coatings. Approximately 200,000 tons of alkyd resins are produced each year. They are based on linking reactive monomers with through ester formation. Polyols used in the production of commercial alkyd resins are glycerol, trimethylolpropane, and pentaerythritol.[2]

Pentaerythritol
Pentaerythritol is a classic polyol used in the preparation of alkyd resins.

Polyols react with isocyanates to make polyurethanes, which find use to make mattresses, foam insulation for refrigerators and freezers, home and automotive seats, elastomeric shoe soles, fibers (e.g. Spandex), and adhesives.

Nanoscience

The preparation of metal nanoparticles often employ the "polyol method." In such cases, the polyol is usually a long chain diol such as hexadecanediol ((CH2)16(OH)2). Such diols serve as both reductants and surface-protecting agents for the nanoparticles.[3]

See also

References

  1. ^ Hubert Schiweck, Albert Bär, Roland Vogel, Eugen Schwarz, Markwart Kunz, Cécile Dusautois, Alexandre Clement, Caterine Lefranc, Bernd Lüssem, Matthias Moser, Siegfried Peters (2012). "Sugar Alcohols". Ullmann's Encyclopedia of Industrial Chemistry. Weinheimdoi=10.1002/14356007.a25_413.pub3: Wiley-VCH.CS1 maint: Uses authors parameter (link)
  2. ^ Frank N. Jones, "Alkyd Resins", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a01_409
  3. ^ Park, Jongnam; Joo, Jin; Kwon, Soon Gu; Jang, Youngjin; Hyeon, Taeghwan (2007). "Synthesis of monodisperse spherical nanocrystals". Angewandte Chemie International Edition. 46: 4630–4660. doi:10.1002/anie.200603148.CS1 maint: Uses authors parameter (link)

External links

  • Media related to Polyols at Wikimedia Commons
Aldose reductase

In enzymology, aldose reductase (or aldehyde reductase) (EC 1.1.1.21) is a cytosolic NADPH-dependent oxidoreductase that catalyzes the reduction of a variety of aldehydes and carbonyls, including monosaccharides. It is primarily known for catalyzing the reduction of glucose to sorbitol, the first step in polyol pathway of glucose metabolism.

Aldose reductase inhibitor

Aldose reductase inhibitors are a class of drugs being studied as a way to prevent eye and nerve damage in people with diabetes.

Chewing gum

Chewing gum is a soft, cohesive substance designed to be chewed without being swallowed. Modern chewing gum is composed of gum base, sweeteners, softeners/plasticizers, flavors, colors, and, typically, a hard or powdered polyol coating. Its texture is reminiscent of rubber because of the physical-chemical properties of its polymer, plasticizer, and resin components, which contribute to its elastic-plastic, sticky, chewy characteristics.

Diabetic neuropathy

Diabetic neuropathies are nerve damaging disorders associated with diabetes mellitus. These conditions are thought to result from a diabetic microvascular injury involving small blood vessels that supply nerves (vasa nervorum) in addition to macrovascular conditions that can accumulate in diabetic neuropathy. Relatively common conditions which may be associated with diabetic neuropathy include third, fourth, or sixth cranial nerve palsy; mononeuropathy; mononeuropathy multiplex; diabetic amyotrophy; a painful polyneuropathy; autonomic neuropathy; and thoracoabdominal neuropathy.

Epalrestat

Epalrestat is a carboxylic acid derivative and a noncompetitive and reversible aldose reductase inhibitor used for the treatment of diabetic neuropathy, which is one of the most common long-term complications in patients with diabetes mellitus. It reduces the accumulation of intracellular sorbitol which is believed to be the cause of diabetic neuropathy, retinopathy and nephropathy It is well tolerated, with the most commonly reported adverse effects being gastrointestinal issues such as nausea and vomiting, as well as increases in certain liver enzymes.

Chemically, epalrestat is unusual in that it is a drug that contains a rhodanine group.

Aldose reductase is the key enzyme in the polyol pathway whose enhanced activity is the basis of diabetic neuropathy. Aldose reductase inhibitors (ARI) target this enzyme. Out of the many ARIs developed, ranirestat and fidarestat are in the trial stage. Others have been discarded due to unacceptable adverse effects or weak efficacy. Epalrestat is the only ARI commercially available. It is easily absorbed into the neural tissue and inhibits the enzyme with minimum side effects.

Erythritol

Erythritol is a sugar alcohol (or polyol) that is considered safe (GRAS) as a food additive in the United States and throughout much of the world. It was discovered in 1848 by Scottish chemist John Stenhouse. Erythritol was first isolated in 1852. In 1950 it was found in blackstrap molasses that was fermented by yeast, and it became commercialized as a sugar alcohol in the 1990s in Japan.It occurs naturally in some fruit and fermented foods. At the industrial level, it is produced from glucose by fermentation with a yeast, Moniliella pollinis. Erythritol is 60–70% as sweet as sucrose (table sugar) yet it is almost noncaloric, does not affect blood sugar, does not cause tooth decay, and is partially absorbed by the body, excreted in urine and feces. Under U.S. Food and Drug Administration (FDA) labeling requirements, it has a caloric value of 0.2 kilocalories per gram (95% less than sugar and other carbohydrates), though nutritional labeling varies from country to country. Some countries, such as Japan and the United States, label it as zero-calorie; the European Union labels it 0 kcal/g.

Gallotannin

A gallotannin is any of a class of molecules belonging to the hydrolysable tannins. Gallotannins are polymers formed when gallic acid, a polyphenol monomer, esterifies and binds with the hydroxyl group of a polyol carbohydrate such as glucose.

Hydrogenated starch hydrolysates

Hydrogenated starch hydrolysates (HSHs) are mixtures of several sugar alcohols (a type of sugar substitute). Hydrogenated starch hydrolysates were developed by the Swedish company Lyckeby Starch in the 1960s. The HSH family of polyols is an approved food ingredient in Canada, Japan, and Australia. HSH sweeteners provide 40 to 90% sweetness relative to table sugar.

Hydrogenated starch hydrolysates are produced by the partial hydrolysis of starch – most often corn starch, but also potato starch or wheat starch. This creates dextrins (glucose and short glucose chains). The hydrolyzed starch (dextrin) then undergoes hydrogenation to convert the dextrins to sugar alcohols.

Hydrogenated starch hydrolysates are similar to sorbitol: if the starch is completely hydrolyzed so that only single glucose molecules remain, then after hydrogenation the result is sorbitol. Because in HSHs the starch is not completely hydrolyzed, a mixture of sorbitol, maltitol, and longer chain hydrogenated saccharides (such as maltotriitol) is produced. When no single polyol is dominant in the mix, the generic name hydrogenated starch hydrosylates is used. However, if 50% or more of the polyols in the mixture are of one type, it can be labeled as "sorbitol syrup", or "maltitol syrup", etc.

Maltitol

Maltitol is a sugar alcohol (a polyol) used as a sugar substitute. It has 75–90% of the sweetness of sucrose (table sugar) and nearly identical properties, except for browning. It is used to replace table sugar because it is half as caloric, does not promote tooth decay, and has a somewhat lesser effect on blood glucose. In chemical terms, maltitol is known as 4-O-α-glucopyranosyl-D-sorbitol. It is used in commercial products under trade names such as Lesys, Maltisweet and SweetPearl.

Manali Petrochemical

Manali Petrochemical Ltd. (MPL) is a petrochemical company based in India. It markets propylene glycol and polyols It is based in Chennai.

Manali Petrochemical annually produces 27000 metric tonnes of propylene oxide, 14,000 metric tonnes of propylene glycol and 15,000 metric tonnes of polyether polyol and system polyol.Manali Petrochemical Ltd Plant-I (originally built by SPIC) set up with the technology of Atochem for manufacture of PO and PG and that of Arco for manufacture of Polyuol acquired through Technip, France. Manali Petrochemical Ltd Plant-II (originally joint venture of UB and TIDCO) was merged with MPL later utilizes the technology of Enichem of Italy for the PO and PG and Press Industrial for manufacture of Polyol.MPL markets its Polyols with isocyanates sourced indigenously as well as imported from Japan and China and the pre-polymers produced at MPL in meeting the demand of polyurethane industry in India.

Mannitol dehydrogenase (cytochrome)

In enzymology, a mannitol dehydrogenase (cytochrome) (EC 1.1.2.2) is an enzyme that catalyzes the chemical reaction

D-mannitol + ferricytochrome c D-fructose + ferrocytochrome c

Thus, the two substrates of this enzyme are D-mannitol and ferricytochrome c, whereas its two products are D-fructose and ferrocytochrome c.

This enzyme belongs to the family of oxidoreductases, to be specific those acting on the CH-OH group of donor with a cytochrome as acceptor. The systematic name of this enzyme class is D-mannitol:ferricytochrome-c 2-oxidoreductase. This enzyme is also called polyol dehydrogenase. This enzyme participates in pentose and glucuronate interconversions and fructose and mannose metabolism

NanoCLAMP

In the medical field of immunology, nanoCLAMP (CLostridal Antibody Mimetic Proteins) affinity reagents are recombinant 15 kD antibody mimetic proteins selected for tight, selective and gently reversible binding to target molecules. The nanoCLAMP scaffold is based on an IgG-like, thermostable carbohydrate binding module family 32 (CBM32) from a Clostridium perfringens hyaluronidase (Mu toxin). The shape of nanoCLAMPs approximates a cylinder of approximately 4 nm in length and 2.5 nm in diameter, roughly the same size as a nanobody (PDB: 2W1Q​). nanoCLAMPs to specific targets are generated by varying the amino acid sequences and sometimes the length of three solvent exposed, adjacent loops that connect the beta strands making up the beta-sandwich fold, conferring binding affinity and specificity for the target.

Otto Bayer

Otto Bayer (November 4, 1902 in Frankfurt – August 1, 1982 in Burscheid) was a German industrial chemist at IG Farben who was head of the research group that in 1937 discovered the polyaddition for the synthesis of polyurethanes out of poly-isocyanate and polyol.Dr. Bayer was not related to the founding family of Bayer Corp. Today polyurethanes are ubiquitous throughout modern life. He was a member of the board of directors and of the supervisory board of Bayer, and was also vice chairman of the supervisory board of Cassella in the 1950s.

Bayer was the 1975 recipient of the Charles Goodyear Medal.

Pentaerythritol

Pentaerythritol is an organic compound with the formula C(CH2OH)4. Classified as a polyol, it is a white solid. Pentaerythritol is a building block for the synthesis and production of explosives, plastics, paints, appliances, cosmetics, and many other commercial products.

The word pentaerythritol is a portmanteau of penta- in reference to the number of carbon atoms and erythritol, which also possess 4 alcohol groups.

Polyisocyanurate

Polyisocyanurate, also referred to as PIR, polyiso, or ISO, is a thermoset plastic typically produced as a foam and used as rigid thermal insulation. The starting materials are similar to those used in polyurethane (PUR) except that the proportion of methylene diphenyl diisocyanate (MDI) is higher and a polyester-derived polyol is used in the reaction instead of a polyether polyol. The resulting chemical structure is significantly different, with the isocyanate groups on the MDI trimerising to form isocyanurate groups which the polyols link together, giving a complex polymeric structure.

Polyol pathway

Also called the sorbitol-aldose reductase pathway, the polyol pathway is a two-step process that converts glucose to fructose. In this pathway glucose is reduced to sorbitol, which is subsequently oxidized to fructose.

The pathway is implicated in diabetic complications, especially in microvascular damage to the retina, kidney, and nerves.Sorbitol cannot cross cell membranes, and, when it accumulates, it produces osmotic stresses on cells by drawing water into the insulin-independent tissues.

Polyurea

Polyurea is a type of elastomer that is derived from the reaction product of an isocyanate component and a synthetic resin blend component through step-growth polymerization. The isocyanate can be aromatic or aliphatic in nature. It can be monomer, polymer, or any variant reaction of isocyanates, quasi-prepolymer or a prepolymer. The prepolymer, or quasi-prepolymer, can be made of an amine-terminated polymer resin, or a hydroxyl-terminated polymer resin.

The resin blend may be made up of amine-terminated polymer resins, and/or amine-terminated chain extenders. The amine-terminated polymer resins do not have any intentional hydroxyl moieties. Any hydroxyls are the result of incomplete conversion to the amine-terminated polymer resins. The resin blend may also contain additives or non-primary components. These additives may contain hydroxyls, such as pre-dispersed pigments in a polyol carrier. Normally, the resin blend does not contain a catalyst(s).

Polyurethane

Polyurethane (PUR and PU) is a polymer composed of organic units joined by carbamate (urethane) links. While most polyurethanes are thermosetting polymers that do not melt when heated, thermoplastic polyurethanes are also available.

Polyurethane polymers are traditionally and most commonly formed by reacting a di- or tri poly-isocyanate with a polyol. Since polyurethanes contain two types of monomers, which polymerise one after the other, they are classed as alternating copolymers. Both the isocyanates and polyols used to make polyurethanes contain, on average, two or more functional groups per molecule.

Polyurethanes are used in the manufacture of high-resilience foam seating, rigid foam insulation panels, microcellular foam seals and gaskets, durable elastomeric wheels and tires (such as roller coaster, escalator, shopping cart, elevator, and skateboard wheels), automotive suspension bushings, electrical potting compounds, high performance adhesives, surface coatings and surface sealants, synthetic fibers (e.g., Spandex), carpet underlay, hard-plastic parts (e.g., for electronic instruments), condoms, and hoses.

Quinic acid

Quinic acid is a cyclitol, a cyclic polyol, and a cyclohexanecarboxylic acid. It is a colorless solid that can be extracted from plant sources. Quinic acid is implicated in the perceived acidity of coffee.

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