Phenol
From Wikipedia, the free encyclopedia
| Phenol | |
|---|---|
|
|
| Systematic name | Phenol |
| Other names | Carbolic Acid Benzenol Phenylic Acid Hydroxybenzene Phenic acid |
| Chemical formula | C6H5OH |
| SMILES | OC1=CC=CC=C1 |
| Molar mass | 94.11 g/mol |
| Appearance | White Crystalline Solid |
| CAS number | [108-95-2] |
| Properties | |
| Density | 1.07 g/cm3 |
| Solubility in water | 8.3 g/100 ml (20 °C) |
| Melting point | 40.5 °C |
| Boiling point | 181.7 °C |
| Acidity (pKa) | 9.95 |
| Structure | |
| Molecular shape | planar |
| Dipole moment | ? D |
| Hazards | |
| MSDS | External MSDS |
| EU classification | Toxic (T) Muta. Cat. 3 Corrosive (C) |
| NFPA 704 |
2
4
0
|
| R-phrases | R23/24/25, R34, R48/23/24/25, R68 |
| S-phrases | S1/2, S24/25, S26, S28, S36/37/39, S45 |
| Flash point | 79 °C |
| Autoignition temperature | 715 °C |
| RTECS number | SJ3325000 |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Related compounds | Benzenethiol |
| Disclaimer and references | |
Phenol, also known under an older name of carbolic acid, is a colourless crystalline solid with a typical sweet tarry odor. Its chemical formula is C6H5OH and its structure is that of a hydroxyl group (-OH) bonded to a phenyl ring; it is thus an aromatic compound.
[edit] Phenols
The word phenol is also used to refer to any compound which contains a six-membered aromatic ring, bonded directly to a hydroxyl group (-OH). In effect, phenols are a class of organic compounds of which the phenol discussed in this article is the simplest member.
[edit] Properties
Phenol has a limited solubility in water (8.3 g/100 ml). It is slightly acidic: the phenol molecule has weak tendencies to lose the H+ ion from the hydroxyl group, resulting in the highly water-soluble phenoxide anion C6H5O−. Compared to aliphatic alcohols, phenol shows much higher acidity; it even reacts with NaOH to lose H+ whereas aliphatic alcohols do not. Contrary to popular belief, this has little to do with orbital overlap between the oxygen's lone pairs and the aromatic system.
While the aromaticity of the benzene ring allows the delocalization the negative charge throughout the ring to stabilizes the anion, the dominant effect is the induction from the sp2 hybridized carbons (the comparatively more powerful inductive withdrawal of electron density that is provided by the sp2 system compared to an sp3 system allows for great stabilization of the oxyanion). In making this conclusion, we cite the pKa of acetone enol, which is 10.9 (in comparison to phenol with a pKa of 10.0). For further reading on the fine points of this topic, see David A. Evans's explanation.
[edit] Production
Phenol can be made from the partial oxidation of benzene or benzoic acid, by the cumene process, or by the Raschig process. It can also be found as a product of coal oxidation.
[edit] Uses
Phenol has antiseptic properties, and was used by Sir Joseph Lister(1827-1912) in his pioneering technique of antiseptic surgery, though the skin irritation caused by continual exposure to phenol eventually led to the substitution of aseptic (germ-free) techniques in surgery. It is one of the main components of the commercial antiseptic TCP (trichlorophenol). It is also the active ingredient in some oral anesthetics such as Chloraseptic spray. Phenol was also the main ingredient of the Carbolic Smoke Ball, a device sold in London designed to protect the user against influenza and other ailments. In the early part of the 20th century, it was used in the Battle Creek Sanitarium to discourage female masturbation.[1]
It is also used in the production of drugs (it is the starting material in the industrial production of aspirin), weedkiller, and synthetic resins (Bakelite, one of the first synthetic resins to be manufactured, is a polymer of phenol with formaldehyde). Exposure of the skin to concentrated phenol solutions causes chemical burns which may be severe; in laboratories where it is used, it is usually recommended that polyethylene glycol solution is kept available for washing off splashes. Washing with large amounts of plain water (most labs have a safety shower or eye-wash) and removal of contaminated clothing are required, and immediate ER treatment for large splashes; particularly if the phenol is mixed with chloroform (a commonly used mixture in molecular biology for DNA purification). Notwithstanding the effects of concentrated solutions, it is also used in cosmetic surgery as an exfoliant, to remove layers of dead skin. It is also used in phenolization, a surgical procedure used to treat an ingrown nail, in which it is applied to the toe to prevent regrowth of nails.
Injections of phenol have occasionally been used as a means of rapid execution. In particular, phenol was used as a means of extermination by the Nazis during the Second World War. Phenol injections were given to thousands of people in concentration camps, especially at Auschwitz-Birkenau. Injections were administered either by medical doctors or by their assistants; such injections were originally given intravenously, more commonly in the arm, but injection directly into the heart, so as to induce nearly instant death, was later preferred. [2]
[edit] See also
[edit] References
- ^ Wealthy Eccentrics. CNN.com. Retrieved on February 23, 2007.
- ^ Killing through phenol injection. Auschwitz - FINAL STATION EXTERMINATION. Johannes Kepler University, Linz, Austria. Retrieved on September 29, 2006.
