Phenol

**Phenol**, also known as **carbolic acid** and **phenic acid**, is an [|organic compound] with the [|chemical formula] C6H5OH. It is a white [|crystalline][|solid] at room temperature. The molecule consists of a [|phenyl group] (-C6H5) bonded to a [|hydroxyl group] (-OH). It is mildly [|acidic], but requires careful handling due to its propensity to cause burns. Phenol was first extracted from [|coal tar], but today is produced on an large scale (about 7 billion kg/year) using industrial processes. It is an important industrial commodity as a precursor to many materials and useful compounds. [|[4]] Its major uses involve its conversion to plastics or related materials. Phenol and its chemical [|derivatives] are key for building [|polycarbonates], [|epoxies] , [|Bakelite] , [|nylon] , detergents and a large collection of drugs and herbicides.

Properties
Phenol is appreciably [|soluble] in water, with about 8.3 g dissolving in 100 mL (0.88 [|M] ). Homogeneous mixtures of phenol and water at phenol to water mass ratios of ~2.6 and higher are also possible. The sodium salt of phenol, sodium phenoxide, is far more water soluble.

Acidity
It is slightly acidic: the phenol molecules have weak tendencies to lose the H+ ion from the hydroxyl group, resulting in the highly water-soluble **phenolate** [|anion] C6H5O− (also called **phenoxide**). [|[5]] Compared to [|aliphatic] [|alcohols], phenol is about 1 million times more acidic, although it is still considered a weak acid. It reacts completely with [|aqueous] [|NaOH] to lose H+, whereas most [|alcohols] react only partially. Phenols are less acidic than [|carboxylic acids], and even [|carbonic acid]. One explanation for the increased acidity over alcohols is [|resonance stabilization] of the phenoxide anion by the aromatic ring. In this way, the negative charge on oxygen is shared by the [|ortho] and [|para] carbon atoms. [|[6]] In another explanation, increased acidity is the result of orbital overlap between the oxygen's lone pairs and the aromatic system. [|[7]] In a third, the dominant effect is the [|induction] from the [|sp2 hybridised carbons] ; the comparatively more powerful inductive withdrawal of electron density that is provided by the sp2 system compared to an sp3system allows for great stabilization of the oxyanion. In making this conclusion, one can examine the [|pKa] of the [|enol] of [|acetone], which is 19.0, in comparison to phenol with a pKa of 10.0. [|[8]] However, this similarity of acidities of phenol and acetone enol is not observed in the gas phase, and is because the difference of solvation energies of the deprotonated acetone enol and phenoxide almost exactly offsets the experimentally observed gas phase acidity difference. It has recently been shown that only about 1/3 of the increased acidity of phenol is due to inductive effects, with resonance accounting for the rest. [|[9]]

Uses

 * The primary use of phenol is in the production of phenolic resins, which are used in the plywood, construction, automotive, and appliance industries. ( [|1] )
 * Phenol is also used in the production of caprolactam and bisphenol A, which are intermediates in the manufacture of nylon and epoxy resins, respectively. ( [|1] )
 * Other uses of phenol include as a slimicide, as a disinfectant, and in medicinal products such as ear and nose drops, throat lozenges, and mouthwashes. ( [|1] )

Sources and Potential Exposure

 * Individuals may be exposed to phenol through breathing contaminated air or through skin contact in the workplace. ( [|1] )
 * Other exposures to phenol may occur through the use of phenol-containing medicinal products (including mouthwashes, toothache drops, throat lozenges, analgesic rubs, and antiseptic lotions) or smoking tobacco. ( [|1] )

Assessing Personal Exposure

 * Phenol can be detected in urine; this test can be used to determine whether a person has recently been exposed to phenol or to substances that are changed to phenol in the body. However, no test will tell whether a person has been exposed only to phenol, because many substances are changed to phenol in the body. ( [|1] )

Health Hazard Information

 * //Acute Effects:// **


 * Inhalation and dermal exposure to phenol is highly irritating to the skin, eyes, and mucous membranes in humans. ( [|1] - [|3] )
 * Symptoms of acute toxicity in humans include irregular breathing, muscle weakness and tremors, loss of coordination, convulsions, coma, and respiratory arrest at lethal doses. ( [|1] - [|3] )
 * Acute animal tests in rats, mice, and rabbits have shown phenol to have [|high] acute toxicity from oral exposure. ( [|4] )


 * //Chronic Effects// (Noncancer): **


 * Anorexia, progressive weight loss, diarrhea, vertigo, salivation, and a dark coloration of the urine have been reported in chronically exposed humans. Gastrointestinal irritation and blood and liver effects have also been reported. ( [|1] )
 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">In one study, muscle pain, weakness, enlarged liver and elevated levels of liver enzymes were found in an individual after inhalation and dermal exposure to phenol and a few other chemicals. ( [|1] )
 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">Application of phenol to the skin results in dermal inflammation and necrosis. Cardiac arrhythmias have also been reported in humans exposed to high concentrations of phenol. ( [|1] )
 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">Chronic inhalation exposure of animals to phenol has shown central nervous systems (CNS), kidney, liver, respiratory, and cardiovascular effects. ( [|1] )
 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">The Reference Dose ( [|RfD] ) for phenol is 0.6 milligrams per kilogram body weight per day (mg/kg/d) based on reduced fetal body weights in rats. The [|RfD] is an estimate (with uncertainty spanning perhaps an order of magnitude) of a daily oral exposure to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious noncancer effects during a lifetime. It is not a direct estimator of risk but rather a reference point to gauge the potential effects. At exposures increasingly greater than the [|RfD], the potential for adverse health effects increases. Lifetime exposure above the [|RfD] does not imply that an adverse health effect would necessarily occur. ( [|5] )
 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">EPA has low confidence in the study on which the [|RfD] was based because the dose was administered by gavage; medium confidence in the database because it contains several supporting studies (subchronic, chronic, and reproductive/ developmental); and, consequently, low-to-medium confidence in the [|RfD] . ( [|5] )
 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">EPA has established a provisional Reference Concentration ( [|RfC] ) for phenol of 0.006 milligrams per cubic meter (mg/m3) based on no effects in rats, mice, or monkeys. The provisional [|RfC] is a value that has had some form of Agency review, but it does not appear on IRIS. ( [|13] )


 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">//Reproductive/ Developmental Effects:// **


 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">No studies were located concerning the developmental or reproductive effects of phenol in humans.
 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">Animal studies have reported reduced fetal body weights, growth retardation, and abnormal development in the offspring of animals exposed to phenol by the oral route. Decreased maternal weight gain and increased maternal mortality were also observed. ( [|1], [|3] , [|5] )


 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">//Cancer Risk:// **


 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">Small, non-significant excesses in certain types of cancers were reported in occupationally exposed workers; however, these effects were not clearly related to phenol exposure. ( [|1] )
 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">Animal studies have not seen tumors resulting from oral exposure to phenol, while dermal studies have reported that phenol applied to the skin may be a tumor promotor and/or a weak skin carcinogen in mice. ( [|1], [|2] , [|5] )
 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">EPA has classified phenol as a Group D, not classifiable as to human carcinogenicity, based on a lack of data concerning carcinogenic effects in humans and animals. ( [|5] )

<span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 1.35em;">Physical Properties

 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">Phenol is a colorless or white solid when it is pure; however, it is usually sold and used as a liquid. ( [|1] )
 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">The odor threshold for phenol is 0.04 parts per million (ppm), with a strong very sweet odor reported. ( [|1], [|7] )
 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">Phenol is very soluble in water and is quite flammable. ( [|2] )
 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">The chemical formula for phenol is C6H6O and the molecular weight is 94.1 g/mol. ( [|8], [|9] )
 * <span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">The vapor pressure for phenol is 0.3513 mm Hg at 25 °C, and it has a log octanol/water partition coefficient (log Kow) of 1.46. ( [|1] )

<span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">**Conversion Factors (only for the gaseous form):**

<span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 12px;">//To convert concentrations in air (at 25 °C) from ppm to mg/m3: mg/m3 = (ppm) × (molecular weight of the compound)/(24.45). For phenol: 1 ppm = 3.85 mg/m3.//

<span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 1.35em; text-align: -webkit-center;">Health Data from Inhalation Exposure
===<span style="background-color: #ffffff; font-family: Verdana,Tahoma,sans-serif; font-size: 1.35em; text-align: -webkit-center;"> === High Phenol Foods

Phenolics are chemicals naturally occurring in many foods but may also be

present in additives. Sensitive children have a threshold for tolerance.

Parents need to monitor total load of phenols through the day to avoid

tipping the child into a reaction from the accumulated phenols.

Phenolic compounds give colour, taste, flavour and smell to foods. They

are also present in salicylates, amines, colours and preservatives.

High phenol foods include:

– food dyes, -tomatoes,

– apples, -peanuts,

– bananas, -chocolate

– oranges -orange juice

– cocoa, -red grapes

– milk./cheese -Vanillin flavour

– carob -Strong odours

Typical possible reactions to an over accumulation of phenolic foods in a

sensitive child may include some of the following:

• Red ears and/or face

• Night sweats

• Smelly head /bed/stools-acrid

• Bloated stomach, rash, thirst

• Poor toxin removal

• Poor tolerance of high phenol foods

• Dark circles under the eyes

• Hyperactivity, aggression

• Headache, head banging or other self-injury

• Inappropriate laughter

• Difficulty falling asleep at night, and night waking for several hours