Пропиленгликоль

Описание

Propylene glycol is used as antifreeze in breweries and diaries, in the manufacture of resins, as a solvent, and as an emulsifier in food. It was present as an occupational sensitizer in the color-film developer Flexicolor.

Химические свойства

Propylene glycol is a colorless, odorless, syrupy liquid.

Вхождение

Reported found in several varieties of mushrooms, roasted sesame seed, oat groats, parmesan cheese, cocoa, pecans and truffle.

Использование

Next to water, propylene glycol is the most common moisturecarrying vehicle used in cosmetic formulations. It has better skin permeation than glycerin, and it also gives a pleasant feel with less greasiness than glycerin. Propylene glycol is used as a humectant because it absorbs water from the air. It also serves as a solvent for anti-oxidants and preservatives. In addition, it has preservative properties against bacteria and fungi when used in concentrations of 16 percent or higher. There is a concern that propylene glycol is an irritant at high concentrations, though it appears to be quite safe at usage levels under 5 percent.

Определение

An alcohol in which the hydroxyl groups are attached to a carbon atom of a branched or straight-chain aliphatic hydrocarbon.

Показания

Propylene glycol solution (40% to 60%, v/vCH2CH[OH]CH2OH, propylene glycol) applied to the skin under plastic occlusion hydrates the skin and causes desquamation of scales. Propylene glycol, isotonic in 2% concentration, is a widely used vehicle in dermatologic preparations. Hydroalcoholic gels containing propylene glycol or other substances augment the keratolytic action of salicylic acid. Keralyt gel consists of 6% salicylic acid, 19.4% alcohol, hydroxypropylcellulose, propylene glycol, and water and is an extremely effective keratolytic agent. Overnight occlusion is used nightly until improvement is evident, at which time the frequency of therapy can be decreased to every third night or once weekly. This therapy is well tolerated, is usually nonirritating, and has been most successful in patients with X-linked ichthyosis vulgaris. Burning and stinging may occur when applied to damaged skin. Patients with other abnormalities of keratinization with hyperkeratosis, scaling, and dryness may also benefit.

Методы производства

Propylene glycol generally is synthesized commercially by starting with propylene, converting to the chlorohydrin, and hydrolyzing to propylene oxide, which is then hydrolyzed to propylene glycol. It can also be prepared by other methods.

Подготовка

Manufactured by treating propylene with chlorinated water to form the chlorohydrin, which is converted to the glycol by treatment with sodium carbonate solution. It is also prepared by heating glycerol with sodium hydroxide.

Общее описание

Thick odorless colorless liquid. Mixes with water.

Реакции воздуха и воды

Water soluble.

Профиль реактивности

1,2-Propanediol is hygroscopic. 1,2-Propanediol is sensitive to excessive heat (tends to oxidize at high temperatures). 1,2-Propanediol can react with oxidizing materials. 1,2-Propanediol is incompatible with acid chlorides, acid anhydrides, chloroformates, and reducing agents. 1,2-Propanediol dissolves many essential oils. A mixture of 1,2-Propanediol with hydrofluoric acid and silver nitrate was put in a glass bottle which burst 30 minutes later.

Опасность

Toxic.

Угроза здоровью

Liquid may irritate eyes.

Пожароопасность

1,2-Propanediol is combustible.

Контактные аллергены

Propylene glycol is used as a solvent, a vehicle for topical medicaments such as corticosteroids or aciclovir, an emulsifier and humectant in food and cosmetics, and as antifreeze in breweries, in the manufactures of resins. It was present as an occupational sensitizer in the color film developer Flexicolor?. Patch tests in aqua are sometimes irritant.

Профиль безопасности

Slightly toxic by ingestion, skin contact, intraperitoneal, intravenous, subcutaneous, and intramuscular routes. Human systemic effects by ingestion: general anesthesia, convulsions, changes in surface EEG. Experimental teratogenic and reproductive effects. An eye and human skin irritant. Mutation data reported. Combustible liquid when exposed to heat or flame; can react with oxidizing materials. Explosive in the form of vapor when exposed to heat or flame. May react with hydrofluoric acid + nitric acid + silver nitrate to form the explosive silver fulminate. To fight fire, use alcohol foam. When heated to decomposition it emits acrid smoke and irritating fumes.

Возможный контакт

Propylene glycol is used as a solvent; emulsifying agent; food and feed additive; flavor, in manu- facture of plastics; as a plasticizer, surface-active agent; antifreeze, solvent, disinfectant, hydroscopic agent; coolant in refrigeration systems; pharmaceutical, brake fluid; and many others.

Описание

Пропиленгликоль — бесцветная вязкая жидкость со слабым характерным запахом, сладковатым вкусом, обладающая гигроскопическими свойствами.

Химические свойства

1,2-пропиленгликоль — прозрачная вязкая жидкость. Её плотность ниже, чем у этиленгликоля и глицерина, но выше чем у этанола. Вязкость пропиленгликоля выше, чем у этиленгликоля и одноатомных спиртов, особенно при низких температурах.

Канцерогенность

Dewhurst et al. and Baldwin et al. in studies on the carcinogenicity of other chemicals used propylene glycol as the solvent. As a result they tested propylene glycol alone for carcinogenic activity in rats and mice. Dewhurst et al. used a single injection of 0.2 mL, whereas Baldwin et al. gave rats and mice three to five subcutaneous injections, amount not specified. In neither case were tumors observed during a period of about a year or 2 years .
Wallenious and Lecholm applied propylene glycol to the skin of rats three times a week for 14 months but found no tumor formation. Stenback and Shubik confirmed these findings when they applied propylene glycol at undiluted strength and as a 50 and 10% solution in acetone to the skin of mice during their lifetimes.
No tumors have been reported in the lifetime dietary feeding studies . In fact, Gaunt et al. specifically state that no tumors were found in the rats.

Применение

1,2-Пропиленгликоль применяют:

1.в производстве ненасыщенных полиэфирных смол (для строительной индустрии и производства автомобилей), эластичных полиуретанов, алкидных смол;

2.как растворитель природных и синтетических веществ при приготовлении мазей, паст, кремов, шампуней и т. д. в фармацевтической и косметической промышленности;

3.в пищевой промышленности как растворитель пищевых добавок и увлажнитель табака. 1,2-Пропиленгликоль обладает умеренными консервирующими и бактерицидными свойствами;

4.Для дезинфекции помещений на предприятиях пищевой промышленности (распыляют в воздухе в виде аэрозоля);

5.при изготовлении тормозных жидкостей, антифризов, антиобледенительных жидкостей и теплоносителей;

6.в качестве пластификатора при производстве целлофановых и поливинилхлоридных плёнок;

7.в дымовых машинах для создания визуальных эффектов на концертах, эстрадных шоу, в киноиндустрии;

8.В связи с заменой эфиров этиленгликоля менее токсичными соединениями возрастает применение эфиров 1,2-пропиленгликоля;

9.в жидкости для электронных парогенераторов и ЭСДН.

Экологическая судьба

Propylene glycol can be released into the environment via industrial releases or by disposal of consumer products. Propylene glycol is readily soluble in water and has a low sorption partition coefficient (KOC), so has the ability to move through soil and to leach into ground water. Because of low vapor pressure (0.1 mmHg at 25°C) and high water solubility, there is minimal volatilization to the atmosphere from surface water releases as well as substantial removal of its vapors by wet deposition. Its low octanol/water partition coefficient (KOW) indicates that bioconcentration and biomagnification should not happen. Propylene glycol is readily degraded in surface water and soil, by chemical oxidation and microbial digestion, with a short half-life (1–5 days) in aerobic or anaerobic conditions. It is also rapidly degraded in the atmosphere by photochemical oxidation, with a half-life about 1 day. Although environmental releases can and do occur (airports must monitor storm water runoff of deicing solutions), human health effects are likely to be minor, at least in comparison to effects from potential exposures in clinical scenarios.

Производство

Получение пропиленгликоля осуществляется путём гидратации окиси пропилена при температуре от 160 до 200 градусов и при давлении около 1,6 МПа. При этом выделяется 85,5% пропиленгликоля, 13% дипропиленгликоля и 1,5% трипропиленгликоля. Выделяют гликоли в вакууме на ректификационной колонне. Гарантийный срок хранения продукта — один год со дня изготовления. Пищевой пропиленгликоль хранится около двух лет. В процессе эксплуатации не следует забывать, что при перегреве растворов, содержащих пропиленгликоль, начинается разложение основы и присадок, поэтому возможно ухудшение теплофизических свойств раствора.

Методы очистки

Dry the diol with Na2SO4, decant and distil it under reduced pressure. [Beilstein 1 IV 2468.]

Несовместимости

Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explo- sions. Keep away from alkaline materials, strong acids (especially nitric acid), strong bases, permanganates, dichromates; may cause a violent reaction.

Утилизация отходов

Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber.All federal, state, and local environmental regulations must be observed.