The rapid ingestion of 1 pt about mL of pure ethanol would kill most people, and acute ethanol poisoning kills several hundred people each year—often those engaged in some sort of drinking contest. Ethanol freely crosses into the brain, where it depresses the respiratory control center, resulting in failure of the respiratory muscles in the lungs and hence suffocation.
Ethanol is believed to act on nerve cell membranes, causing a diminution in speech, thought, cognition, and judgment.
It has a high vapor pressure, and its rapid evaporation from the skin produces a cooling effect. It is toxic when ingested but, compared to methanol, is less readily absorbed through the skin. Methanol is oxidized to formaldehyde, which destroys tissue; ethanol is oxidized to acetaldehyde and then acetic acid, a normal metabolite.
From what alkene is ethanol made? Draw its condensed structural formula. Chemical reactions in alcohols occur mainly at the functional group, but some involve hydrogen atoms attached to the OH-bearing carbon atom or to an adjacent carbon atom.
Of the three major kinds of alcohol reactions, which are summarized in Figure 2. The third reaction type—esterification—is covered in Chapter 4 "Carboxylic Acids, Esters", Section 4. As noted in Figure 2. The reaction removes the OH group from the alcohol carbon atom and a hydrogen atom from an adjacent carbon atom in the same molecule:.
Under the proper conditions, it is possible for the dehydration to occur between two alcohol molecules. The entire OH group of one molecule and only the hydrogen atom of the OH group of the second molecule are removed. The two ethyl groups attached to an oxygen atom form an ether molecule.
Ethers are discussed in Section 2. Thus, depending on conditions, one can prepare either alkenes or ethers by the dehydration of alcohols. The following reaction occurs in the Embden—Meyerhof pathway. For more information about metabolic reactions, see Chapter 11 "Metabolic Pathways and Energy Production". Although the participating compounds are complex, the reaction is the same: elimination of water from the starting material.
The idea is that if you know the chemistry of a particular functional group, you know the chemistry of hundreds of different compounds. Primary and secondary alcohols are readily oxidized. We saw earlier how methanol and ethanol are oxidized by liver enzymes to form aldehydes. Because a variety of oxidizing agents can bring about oxidation, we can indicate an oxidizing agent without specifying a particular one by writing an equation with the symbol [O] above the arrow.
For example, we write the oxidation of ethanol—a primary alcohol—to form acetaldehyde—an aldehyde—as follows:. We shall see in Chapter 3 "Aldehydes, Ketones" Section 3. Secondary alcohols are oxidized to ketones.
The oxidation of isopropyl alcohol by potassium dichromate K 2 Cr 2 O 7 gives acetone, the simplest ketone:. Unlike aldehydes, ketones are relatively resistant to further oxidation Chapter 3 "Aldehydes, Ketones" Section 3. These reactions can also be carried out in the laboratory with chemical oxidizing agents. One such oxidizing agent is potassium dichromate.
The balanced equation showing only the species involved in the reaction in this case is as follows:. Alcohol oxidation is important in living organisms. Enzyme-controlled oxidation reactions provide the energy cells need to do useful work. One step in the metabolism of carbohydrates involves the oxidation of the secondary alcohol group in isocitric acid to a ketone group:. Note that the overall type of reaction is the same as that in the conversion of isopropyl alcohol to acetone.
For more information on metabolic reactions, see Chapter 11 "Metabolic Pathways and Energy Production". Tertiary alcohols R 3 COH are resistant to oxidation because the carbon atom that carries the OH group does not have a hydrogen atom attached but is instead bonded to other carbon atoms.
The oxidation reactions we have described involve the formation of a carbon-to-oxygen double bond. Thus, the carbon atom bearing the OH group must be able to release one of its attached atoms to form the double bond. The carbon-to-hydrogen bonding is easily broken under oxidative conditions, but carbon-to-carbon bonds are not.
Therefore tertiary alcohols are not easily oxidized. Write an equation for the oxidation of each alcohol. Use [O] above the arrow to indicate an oxidizing agent. The first step is to recognize the class of each alcohol as primary, secondary, or tertiary. This alcohol has the OH group on a carbon atom that is attached to only one other carbon atom, so it is a primary alcohol. Oxidation forms first an aldehyde and further oxidation forms a carboxylic acid. This alcohol has the OH group on a carbon atom that is attached to three other carbon atoms, so it is a tertiary alcohol.
No reaction occurs. This alcohol has the OH group on a carbon atom that is attached to two other carbon atoms, so it is a secondary alcohol; oxidation gives a ketone. Is W oxidized, reduced, dehydrated, or none of these? Is Y oxidized, reduced, or neither? Alcohols with two OH groups on adjacent carbon atoms are commonly known as glycols. The most important of these is 1,2-ethanediol the common name is ethylene glycol , a sweet, colorless, somewhat viscous liquid.
Another common glycol, 1,2-propanediol, is commonly called propylene glycol. Its physical properties are quite similar to those of ethylene glycol.
Commonly called glycerol or glycerin, 1,2,3-propanetriol is the most important trihydroxy alcohol. Like the two glycols, it is a sweet, syrupy liquid. Glycerol is a product of the hydrolysis of fats and oils. For more information about fats and oils, see Chapter 7 "Lipids", Section 7. Ethylene glycol is the main ingredient in many antifreeze mixtures for automobile radiators. The two OH groups lead to extensive intermolecular hydrogen bonding.
It is also completely miscible with water. Ethylene glycol is also used in the manufacture of polyester fiber and magnetic film used in tapes for recorders and computers.
Ethylene glycol is quite toxic. Because it is sweet, pets often lap up spills of leaked antifreeze from a garage floor or driveway. Sometimes people, especially children, drink it.
As with methanol, its toxicity is due to a metabolite. Liver enzymes oxidize ethylene glycol to oxalate ion. These crystals cause renal damage and can lead to kidney failure and death. Although propylene glycol has physical properties much like those of ethylene glycol, its physiological properties are quite different. Propylene glycol is essentially nontoxic, and it can be used as a solvent for drugs and as a moisturizing agent for foods.
Like other alcohols, propylene glycol is oxidized by liver enzymes. In this case, however, the product is pyruvate ion, a normal intermediate in carbohydrate metabolism. Glycerol, a product of fat metabolism, is essentially nontoxic. Alcohols containing two or more hydroxyl groups can be made. Examples include 1,2-ethanediol ethylene glycol, used in antifreeze and 1,2,3-propanetriol glycerine, used as a solvent for cosmetics and medicines :.
The name of an alcohol comes from the hydrocarbon from which it was derived. The final — e in the name of the hydrocarbon is replaced by -ol , and the carbon atom to which the —OH group is bonded is indicated by a number placed before the name.
The carbon chain contains five carbon atoms. If the hydroxyl group was not present, we would have named this molecule pentane. To address the fact that the hydroxyl group is present, we change the ending of the name to —ol. In this case, since the —OH is attached to carbon 2 in the chain, we would name this molecule 2-pentanol.
Ethers are compounds that contain the functional group —O—. Ethers do not have a designated suffix like the other types of molecules we have named so far. In the IUPAC system, the oxygen atom and the smaller carbon branch are named as an alkoxy substituent and the remainder of the molecule as the base chain, as in alkanes.
For common names, the two branches connected to the oxygen atom are named separately and followed by —ether. The common name for the compound shown in Example 2 is ethylmethyl ether:. Ethers can be obtained from alcohols by the elimination of a molecule of water from two molecules of the alcohol. In the general formula for ethers, R— O —R, the hydrocarbon groups R may be the same or different. Diethyl ether, the most widely used compound of this class, is a colorless, volatile liquid that is highly flammable.
It was first used in as an anesthetic, but better anesthetics have now largely taken its place. Diethyl ether and other ethers are presently used primarily as solvents for gums, fats, waxes, and resins. A general anesthetic acts on the brain to produce unconsciousness and a general insensitivity to feeling or pain. William Morton, a Boston dentist, introduced diethyl ether into surgical practice in This painting shows an operation in Boston in in which diethyl ether was used as an anesthetic.
Inhalation of ether vapor produces unconsciousness by depressing the activity of the central nervous system. Diethyl ether is relatively safe because there is a fairly wide gap between the dose that produces an effective level of anesthesia and the lethal dose. However, because it is highly flammable and has the added disadvantage of causing nausea, it has been replaced by newer inhalant anesthetics, including the fluorine-containing compounds halothane, enflurane, and isoflurane. Unfortunately, the safety of these compounds for operating room personnel has been questioned.
For example, female operating room workers exposed to halothane suffer a higher rate of miscarriages than women in the general population. These three modern, inhalant, halogen-containing, anesthetic compounds are less flammable than diethyl ether. The compound has the general formula R— O —R, so it is an ether. The compound has two hydroxyl —OH groups, so it is an alcophol.
Austin State University with contributing authors. Learning Objectives Describe the structure and properties of alcohols, ethers and phenols. Know the name and uses of simple alcohols, phenols and ethers. Nomenclature of Alcohols Alcohols with one to four carbon atoms are frequently called by common names, in which the name of the alkyl group is followed by the word alcohol : According to the International Union of Pure and Applied Chemistry IUPAC , the name of an alcohol comes from the hydrocarbon from which it was derived.
How should it be named? Solution The carbon chain contains five carbon atoms. Solution The carbon chain contains four carbon atoms. Note "Always place the OH on the lowest possible number for the chain. Answer a. Methanol Methyl Alcohol Methanol , also known as methyl alcohol among others, is a chemical with the formula C H 3 O H a methyl group linked to a hydroxyl group , often abbreviated MeOH.
Ethanol Ethyl Alcohol Ethanol also called ethyl alcohol , grain alcohol , drinking alcohol , or simply alcohol is a chemical compound , a simple alcohol with the chemical formula C 2 H 6 O. It has long been prepared by humans harnessing the metabolic efforts of yeasts in fermenting various sugars: Large quantities of ethanol for industrial use are synthesized from the addition reaction of water with ethylene using an acid as a catalyst: Ethanol also has medical applications as an antiseptic and disinfectant.
Toxicity of Alcohols With respect to acute toxicity, simple alcohols have low acute toxicities. Rubbing alcohol is undrinkable even if it is ethanol based, due to the bitterants added. Product labels for rubbing alcohol include a number of warnings about the chemical, including the flammability hazards and its intended use only as a topical antiseptic and not for internal wounds or consumption.
It should be used in a well-ventilated area due to inhalation hazards. Poisoning can occur from ingestion, inhalation, absorption, or consumption of rubbing alcohol. Multifunctional Alcohols A polyol is an organic compound containing multiple hydroxyl groups. Examples include 1,2-ethanediol ethylene glycol, used in antifreeze and 1,2,3-propanetriol glycerine, used as a solvent for cosmetics and medicines : Ethylene glycol IUPAC name: ethane-1,2-diol is an organic compound with the formula CH 2 OH 2.
Source: Wikipedia Forty-five percent of propylene glycol produced is used as chemical feedstock for the production of unsaturated polyester resins. Phenols Compounds in which an OH group is attached directly to an aromatic ring are designated ArOH and called phenols.
Image used with permisison from Wikipedia. To Your Health: Phenols and Us Phenols are widely used as antiseptics substances that kill microorganisms on living tissue and as disinfectants substances intended to kill microorganisms on inanimate objects such as furniture or floors.
Ethers Ethers are compounds that contain the functional group —O—. To Your Health: Ethers as General Anesthetics A general anesthetic acts on the brain to produce unconsciousness and a general insensitivity to feeling or pain. Solution a. Summary The —OH group is the functional group of an alcohol. Various alcohols have a wide range of applications in the medical field as well as in the transportation, food, cosmetic industries.
The name of an alcohol comes from the hydrocarbon from which it was derived. The —R—O—R— group is the functional group of an ether. This is both an advantage and a disadvantage in synthesis. To avoid interference by hydroxyl groups, it often is necessary to protect or mask them by conversion to less reactive functions.
In the case of alcohols the hydroxyl group may be protected by formation of an ether, an ester, or an acetal. These compounds may be classified further as open-chain, cyclic, saturated, unsaturated, aromatic, and so on. John D. Robert and Marjorie C. Caserio Basic Principles of Organic Chemistry, second edition.
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