How do I dissolve phenol in water

phenol

This article explains the chemical substance phenol, the substance group of the same name is described under phenols. The article phenol (ship) describes the steam tanker.

The phenol (IUPAC: Benzene, Obsolete: carbolic acid or short Carbolic) is the simplest representative of the phenols. Phenols are organic compounds in which at least one hydroxyl group is attached directly to an aromatic ring. Phenol is a derivative of benzene. Phenol was discovered in 1834 by the chemist Friedlieb Ferdinand Runge during the distillation of coal tar; however, he referred to the substance as "carbolic acid". Auguste Laurent rediscovered it in 1841 and determined the empirical formula as C.6H6O. Charles Gerhardt named them phenol.[10] The name refers to the coal gas, which was created in addition to coal tar during the production of coke. At that time, illuminating gas (town gas) was used to illuminate cities (gr. phainomei: to shine).

presentation

On an industrial scale, the basic chemical is called phenol by the cumene hydroperoxide process, also known as Phenol synthesis according to Hock (Hock process) known, produced:

Benzene and propene are first converted into isopropylbenzene (cumene) by a Friedel-Crafts alkylation in an acid. Cumene is oxidized by atmospheric oxygen to the hydroperoxide, which decomposes through acidic work-up with rearrangement to phenol and acetone.[11] The simultaneous creation of two easily separable, valuable products makes this process particularly economical.

On a laboratory scale, phenols are also produced by boiling diazonium salts, which are produced by the diazotization of aromatic amino compounds - here aniline - with nitrous acid in the cold:

Another possibility for presentation consists in melting the sodium salt of benzenesulfonic acid with alkali hydroxide:

Phenols are also accessible via the synthesis of an acetophenone, subsequent Baeyer-Villiger oxidation and hydrolysis of the aryl acetate formed.

properties

Phenol is hydroxy substituted benzene. Its melting point is 41 ° C and the boiling point is 182 ° C. Pure phenol forms colorless crystal needles at room temperature, but the commercially available product is i. d. Usually pink to reddish-brown in color due to minor, but intensely colored impurities. It has a characteristic, aromatic odor. In contrast to alcohols, the hydroxyl group of phenol is acidic, making phenol a weak acid. The cause is the mesomerism stabilization of the corresponding base of the phenolate ion. The negative charge can be delocalized into the ring.

In contrast to alcohols, phenols only enter into nucleophilic substitution reactions at high temperatures and in the presence of special catalysts, with the hydroxyl group being replaced by other nucleophiles.[12] The hydroxy function shows a pronounced + M effect, especially in the deprotonated state. In addition, it shows an −I effect. However, since this is significantly smaller than the + M effect, phenol is very easily attacked by electrophiles. The attack takes place preferably in the ortho and para position to the hydroxyl group. Because of the electron-donating nature of the hydroxy group, phenol is about a thousand times more reactive than benzene.

The preference for ortho- or para-attack by electrophiles can be understood by looking at the boundary structures of the phenolate anion. The negative charge is delocalized in the aromatic ring to the ortho and para positions. Since electrophiles prefer to attack electron-rich positions, the observed regioselectivity occurs. Substitution in the para position is also preferred, since there is no steric interaction of the attacking electrophile with the lone electron pairs of the oxygen.

The keto-enol tautomerism is completely on the enol side because of the formation of the thermodynamically favorable aromatic system.

A technically important nucleophilic substitution reaction is the preparation of aniline from phenol at 250 ° C and the presence of an oxide catalyst (aluminum, silicon or magnesium oxide, also boric acid) as "Halcon process“.[13]

$ \ mathrm {C_6H_5OH \ + \ NH_3 \ \ xrightarrow [Cat.] {250 ^ {\ circ} C} \ C_6H_5NH_2 \ + \ H_2O} $

Phenol causes chemical burns and is a nerve / cell poison.

Phenol is converted to cyclohexanol by catalytic hydrogenation.

use

Sir Joseph Lister first used it in 1865 as an antiseptic for disinfecting wounds; However, because of its skin-irritating side effects, it was soon replaced by other antiseptics in surgery.

Because of its bactericidal effect, it is still used today - albeit less often - as a disinfectant.

It is also used as a raw material for the manufacture of medicines, including acetylsalicylic acid, as a herbicide and for the synthesis of synthetic resins. One of the first synthetically manufactured synthetic resin products is Bakelite, a polycondensate made from phenol and formaldehyde.

Phenol water is made from phenol, consisting of ten parts phenol and one part water. Phenolic water is liquid, making it easier to use. In microscopy, phenol water is used for preservation, but also allows color reactions.

In molecular biology, the extraction of organic tissue with mixtures of phenol, chloroform and isoamyl alcohol was one of the first methods to obtain highly pure DNA.

Phenol-resorcinol-formaldehyde adhesives are used in structural timber construction.

During the Second World War, concentration camp doctors, among others, killed prisoners with intracardiac phenol injections.

safety instructions

Phenol is highly toxic both locally and systemically; When exposed to the skin, it has irritating to corrosive effects on mucous membranes, skin and eyes. The eyes can suffer damage in the form of clouding of the cornea, swelling and cohesion of the eyelids up to blindness. Skin contact first leads to reddening of the skin, later to white discoloration; longer exposure time causes a darkening up to the formation of necrosis.[2]

Phenol is mainly absorbed through the skin, but inhalation or oral absorption is also possible. In the human organism, the substance acutely damages the kidneys, blood, central nervous and cardiovascular systems. In the case of chronic exposure, gastrointestinal and nervous disorders, further damage to the liver, kidneys and skin changes are known. Symptoms of intoxication after inhalation were dizziness, headache and ear disorders, vomiting, insomnia and kidney irritation. The ingestion of large amounts led to massive kidney dysfunction up to acute kidney failure within a few hours. Ingestion causes burns in the mouth, throat, esophagus and stomach; swallowing disorders and disorders of the gastrointestinal tract are also known.[2]

The toxicity is attributed to reactive metabolites of phenol, which bind to the DNA and other macromolecules and can cause breaks in the chromosomes and mutagenic effects. An oral dose of 1 g or more can occasionally be fatal for a person; individually, however, much higher doses were survived.[2] The oral LDLo-Value for humans is between 140[8] and 1400 mg / kg body weight; in children the minimum oral lethal dose is 10 mg / kg body weight.[7][9]

Historical description

“It is a substance that has become extremely important for the paint industry and medicine (as a disinfectant). The trade name is still carbolic acid while the scientific name is now phenol; Although this substance has the properties of a weak acid and is able to combine with bases, it is therefore also called phenylic acid or phenic acid, but at the same time and to an even greater extent it plays the role of an alcohol, hence the name phenyl alcohol, which is used in Shortened phenol. Carbolic acid is mainly obtained from coal tar and lignite tar; wood tar only contains extremely small amounts of it, because the creosote of wood tar does not consist of phenol, as was believed for a while, but of the structurally similar cresol, as well as some other substances. In order to obtain the carbolic acid, the part of the tar that passes between 150-200 ° C is treated with caustic soda, which combines with the carbolic acid and the cresol, which is also contained in coal tar, separates this solution from the other tar components and decomposes them with an acid. The oily product which has separated out is then distilled and what passes over 190 ° C. is specially collected; the latter is sold as raw cresol, that which passes below 190 ° C as raw carbolic acid. Both substances in this state are still brown, very foul-smelling, oily liquids. This raw carbolic acid (acidum carbolicum crudum) is partly further purified, partly it is used to preserve wood and to disinfect cesspools. "[14]

Web links

 Wiktionary: phenol - Explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ Phenyl oxide hydrate = phenol
  2. 2,002,012,022,032,042,052,062,072,082,092,10Entry to CAS no. 108-95-2 in the GESTIS substance database of the IFA, accessed on March 28, 2008 (JavaScript required).
  3. ↑ CRC Handbook of Tables for Organic Compound Identification, Third Edition, 1984, ISBN 0-8493-0303-6.
  4. 4,04,1Entry from the CLP regulation too CAS no. 108-95-2 in the GESTIS substance database of the IFA (JavaScript required)
  5. ↑ Since December 1, 2012, only GHS hazardous substance labeling has been permitted for substances. The R-phrases of this substance may still be used to classify preparations until June 1, 2015, after which the EU hazardous substance labeling is of purely historical interest.
  6. ↑ NOAA Material Safety Data Sheet.
  7. 7,07,17,2W. B. Deichmann: Toxicology of Drugs and Chemicals. New York 1969, Academic Press, p. 463.
  8. 8,08,1R. Lefaux, O. H. Cleveland: Practical Toxicology of Plastics. Chemical Rubber Co., 1968, p. 329, 1968.
  9. 9,09,1phenol at ChemIDplus.
  10. ^ Max Bloch, in Günther Bugge, The Book of Great Chemists, Volume 2, pp. 92-114, Verlag Chemie, Berlin, 1930.
  11. ^ Römpp CD 2006, Georg Thieme, 2006
  12. ↑ p. A. Lawrence: Amines: synthesis, properties and applications. P. 80, Cambridge University Press, 2004, ISBN 978-0-521-78284-5
  13. ↑ H.-J. Arpe, K. Weissermel: Industrial organic chemistry: important preliminary and intermediate products. 6th edition, p. 418, Wiley-VCH, 2007, ISBN 978-3-527-31540-6
  14. carbolic acid. In: Merck’s dictionary of goods, 3rd edition, G. A. Gloeckner, Leipzig 1884, pp. 250-251