Phenols



In phenol (C6H5OH).  

Although similar to alcohols, phenols have unique properties and are not classified as alcohols (since the hydroxyl group is not bonded to a saturated carbon atom). They have relatively higher carboxylic acids (their pKa is usually comprised between 10 and 12). Loss of a positive hydrogen ion (H+) from the hydroxyl group of a phenol forms a negative phenolate ion.

Some phenols are germicidal and are used in formulating disinfectants. Others possess estrogenic or endocrine disrupting activity.

Synthesis of phenols

Several laboratory methods for the synthesis of phenols:

  • by an ester rearrangement in the Fries rearrangement
  • by a rearrangement of N-phenylhydroxylamines in the Bamberger rearrangement
  • by ethers
  • by reduction of quinones
  • by replacement of an aromatic amine by an hydroxyl group with water and sodium bisulfide in the Bucherer reaction
  • by hydrolysis of diazonium salts
  • by oligomerisation with formaldehyde + base catalysed reaction with epichlorohydrine to epoxi resin components
  • by reaction with acetone/ketones to e.g. Bisphenol A, an important monomer for resins, e.g. polycarbonate(PC), epoxi resins
  • by a rearrangement reaction of dienones [1] in the dienone phenol rearrangement [2]:

Reactions of phenols

Phenols react in a wide variety of ways.

  • Esterfication reactions and ether formation
  • calixarenes [3]
  • Reaction of naphtols and hydrazines and sodium bisulfite in the Bucherer carbazole synthesis
  • Oxidative cleavage, for instance cleavage of 1,2-dihydroxybenzene to the monomethylester of 2,4 hexadienedioic acid with oxygen, copper chloride in pyridine [4]
  • Oxidative de-aromatization to sodium thiosulfate.

Phenolic compounds

For a full list, see Category:Phenols
chemical synthesis
BHT(butylated hydroxytoluene) - a fat-soluble antioxidant and food additive
chilli peppers
Bisphenol Aand other bisphenols produced from ketones and phenol / cresol
Chavibetolfrom betel, used as a flavouring
creosote
estrogen - hormones
clove
Gallic acidfound in gallnuts
Guaiacol(2-methoxyphenol) - has a smokey flavor, and is found in roasted coffee, whisky, and smoke
nonoxynol-9
Orthophenyl phenola fungicide used for waxing citrus fruits
Picric acid(trinitrophenol) - an explosive material
pH indicator
tannins
Raspberry ketone a compound with an intense raspberry smell
noradrenaline natural neurotransmitters
antiseptic that is used in mouthwashes
amino acid
Xylenol-used in antiseptics & disinfecticides


Medicinals

Cannabinoidsthe active constituents of cannabis
stilbene structure
stilbene structure
Methyl salicylatethe major constituent of the essental oil of wintergreen
Propofola short-acting intravenous anesthetic agent
Psilocybe mushrooms
Aspirin
TCP, an antiseptic.


References

  1. ^ related to quinones, see for example the Zincke-Suhl reaction
  2. ^ Advanced organic Chemistry, Reactions, mechanisms and structure 3ed. page Jerry March ISBN 0-471-85472-7
  3. ^ p-tert-butylcalix[8]arene, Organic Syntheses, CV 8, 80 Article
  4. ^ 2,4-Hexadienedioic acid, monomethyl ester, (Z,Z)- Organic Syntheses, Coll. Vol. 8, p.490 (1993); Vol. 66, p.180 (1988) Article
  5. ^ 2,5-Cyclohexadiene-1,4-dione, 2,3,5-trimethyl Organic Syntheses, Coll. Vol. 6, p.1010 (1988); Vol. 52, p.83 (1972) Abstract.
  6. ^ Oxidative De-aromatization of para-Alkyl Phenols into para-Peroxyquinols and para-Quinols Mediated by Oxone as a Source of Singlet Oxygen M. Carmen Carreño, Marcos González-López, Antonio Urbano Angewandte Chemie International Edition Volume 45, Issue 17 , Pages 2737 - 2741 2006 Abstract
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Phenols". A list of authors is available in Wikipedia.