chem finaIs 1st

• Alcohols

  is an organic compound in whichan —OH group is bonded to a saturatedcarbon atom
• Saturated carbon atom

  is a carbon atom that is bonded to four other atoms.
• OH group

  the functional group that is characteristic of an alcohol, is called a hydroxyl group
• Polyhydroxy alcohols —alcohols that possess morethan one hydroxyl group
• An alcohol in which two hydroxyl groups are present is named as a diol, one containing three hydroxyl groups is named as a triol, and so on. In these names for diols, triols, and so forth, the final -e of the parentalkane name is retained for pronunciation reasons.
• Six commonly encountered alcohols: methyl, ethyl, and isopropyl alcohols (all monohydroxy alcohols), ethylene glycol and propylene glycol (both diols), and glycerol (a triol)
• -Methyl alcohol, with one carbon atom and one —OH group, is the simplest alcohol

  -This colorless liquid is a good fuel for internal combustion engines. (Methyl alcohol fires areeasier to put out than gasoline fires because water mixes with and dilutes methyl alcohol.)

  -Methyl alcohol also has excellent solvent properties, and it is the solvent of choice for paints,shellacs, and varnishes

  -Methyl alcohol is sometimes called wood alcohol, terminology that draws attention to an earlymethod for its preparation—the heating of wood to a high temperature in the absence of air.
• -Drinking methyl alcohol is very dangerous. Within the human body,methyl alcohol is oxidized by the liver enzyme alcohol dehydrogenaseto the toxic metabolites formaldehyde and formic acid.

  -Formaldehyde can cause blindness (temporary or permanent). Formicacid causes acidosis
• -Ethyl alcohol, the two-carbon monohydroxy alcohol, is the alcohol present in alcoholic beverages and is commonly referred to simply as alcohol or drinking alcohol.

  -Like methyl alcohol, ethyl alcohol is oxidized in the human body by the liver enzyme alcohol dehydrogenase

  -Acetaldehyde, the first oxidation product, is largely responsible for the symptoms of hangover.

  -Ethyl alcohol oxidation products are less toxic than those of methyl alcohol
• Ethyl Alcohol (Ethanol) -Long term excessive use of ethyl alcohol may cause undesirable effects such as cirrhosis of the liver, loss of memory, and strongphysiological addiction -Links have also been established between certain birth defects andthe ingestion of ethyl alcohol by women during pregnancy (fetal alcohol syndrome).
• • Ethyl alcohol can be produced by yeast fermentation of sugars found in plant extracts• The synthesis of ethyl alcohol in this manner, from grains such as corn, rice, and barley, is the reason why ethyl alcohol is often called grain alcohol.• Denatured alcohol is ethyl alcohol that has been rendered unfit to drink by the addition of small amounts of toxic substances (denaturing agents). Almost all of the ethyl alcohol used for industrialpurposes is denatured alcohol.
• A 70% isopropyl alcohol–30% water solution is marketed as rubbing alcohol
• Isopropyl alcohol’s rapid evaporation rate creates a dramatic cooling effect when it is applied to the skin, hence its use for alcohol rubs to combat high body temperature.
• Isopropyl alcohol has a bitter taste. Its toxicity is twice that of ethyl alcohol, but it causes few fatalities because it often induces vomiting and thus doesn’t stay down long enough to be fatal
• Large amounts (about 150 mL) of ingested isopropyl alcohol can be fatal; death occurs from paralysis of the central nervous system
• • Ethylene glycol and propylene glycol are the two simplest alcohols possessing two —OH groups.

  • Besides being diols, they are also classified as glycols. A glycol is a diolin which the two —OH groups are on adjacent carbon atoms.

  -Ethylene glycol and propylene glycol are the two simplest alcohols possessing two —OH groups.
• Ethylene Glycol (1,2-Ethanediol) and Propylene Glycol (1,2-Propanediol)

  • Both of these glycols are colorless, odorless, high-boiling liquidsthat are completely miscible with water. Their major uses are asthe main ingredient in automobile “year-round” antifreeze andairplane “de-icers”.

  • Ethylene glycol is extremely toxic when ingested. In the body, liverenzymes oxidize it to oxalic acid. Oxalic acid, as a calcium salt, crystallizes in the kidneys, which leads to renal problems.

  • Propylene glycol, on the other hand, is essentially nontoxic and hasbeen used as a solvent for drugs.
• Glycerol (1,2,3- Propanetriol)

  • Glycerol, which is often also called glycerin, is a clear, thick liquid that has the consistency of honey. Its molecular structure involves three —OH groups on three different carbon atoms.
• Glycerol (1,2,3-Propanetriol)

  -Glycerol is normally present in the human body because it is a product of fat metabolism

  -It is present, in combined form, in all animal fats and vegetable oils

  -In some Arctic species, glycerol functions as a “biological antifreeze”

  -Because glycerol has a great affinity for water vapor (moisture), it is often added to pharmaceutical preparationssuch as skin lotions and soap
• Glycerol (1,2,3-Propanetriol)

  -Florists sometimes use glycerol on cut flowers to help retain water and maintain freshness

  -Its lubricative properties also make it useful in shaving creams and in applications such as glycerol suppositories for rectal administration of medicines
• CLASSIFICATION OF ALCOHOLS

  • Alcohols are classified as primary (1°), secondary (2°), or tertiary (3°) dependingon the number of carbon atoms bonded to the carbon atom that bears the hydroxyl group.

  • A primary alcohol is an alcohol in which the hydroxyl-bearing carbon atom is bonded to only one other carbon atom.

  • A secondary alcohol is an alcohol in which the hydroxyl bearing carbon atom is bonded to two other carbon atoms

  • A tertiary alcohol is an alcohol in which the hydroxyl-bearing carbon atom is bonded to three other carbon atoms
• Combustion

  Hydrocarbons of all types undergo combustion in air to produce carbon dioxide and water. Alcohols are also flammable; as with hydrocarbons, the combustion products are carbon dioxide and water.
• -A dehydration reaction is a chemical reaction in which the components of water (H and OH) are removed from a single reactant or from two reactants (H from one and OH from the other)

  -In intramolecular dehydration, both water components are removedfrom the same molecule
• Intramolecular Alcohol Dehydration

  Reaction conditions for the intramolecular dehydration of an alcohol are a temperature of 180 °C and the presence of sulfuric acid as a catalyst. The dehydration product is an alkene
• Intramolecular Alcohol Dehydration

  • Intramolecular alcohol dehydration is an example of an elimination reaction

  • An elimination reaction is a reaction in which two groups or two atoms on neighboring carbon atoms are removed, or eliminated, from a molecule, leaving a multiple bond between the carbon atoms.
• Intermolecular Alcohol Dehydration

  • At a lower temperature (140 °C) than that required for alkeneformation (180 °C), an intermolecular rather than an intramolecular alcohol dehydration process can occur to produce an ether—a compound with the general structure R—O—R

  • In such ether formation, two alcohol molecules interact, an Hatom being lost from one and an — OH group from the other. The resulting “leftover” portions of the two alcohol molecules join to form the ether
• Intermolecular Alcohol Dehydration

  -The preceding reaction is an example of condensation. A condensationreaction is a chemical reaction in which two molecules combine to form a larger one while liberating a small molecule, usually water.

  -In this case, two alcohol molecules combine to give an ether and water.
• Alcohols undergo halogenation reactions in which a halogen atom issubstituted for the hydroxyl group, producing an alkyl halide
• A phenol is an organic compound in which an —OH group is attached toa carbon atom that is part of an aromatic carbon ring system.
• Phenols

  -The general formula for phenols is Ar–OH, where Ar represents an aryl group

  -An aryl group is an aromatic carbon ring system from which one hydrogen atom has been removed

  -A hydroxyl group is thus the functional group for both phenols and alcohols
• Besides being the name for a family of compounds, phenol is also the IUPAC- approved name for the simplest member of the phenol familyof compounds
• -Methyl and hydroxy derivatives of phenol have IUPAC-accepted common names.

  -Methylphenols are called cresols. The name cresol applies to all three isomeric methylphenols
• For hydroxyphenols, each of the three isomers has a different commonname
• -Phenols are generally low-melting solids or oily liquids at room temperature. Most of them are only slightly soluble in water.

  -Many phenols have antiseptic and disinfectant properties. The simplestphenol, phenol itself, is a colorless solid with a medicinal odor.

  -Its melting point is 41°C, and it is more soluble in water than are most other phenols
• Alcohols vs Phenols

  Both alcohols and phenols are flammable

  Dehydration is a reaction of alcohols but not of phenols; phenols cannotbe dehydrated

  Both alcohols and phenols undergo halogenation in which the hydroxyl group is replaced by a halogen atom in a substitution reaction.
• OCCURRENCE OF AND USES FOR PHENOLS

  • Dilute (2%) solutions of phenol have long been used as antiseptics. Concentrated phenol solutions, however, can cause severe skin burns.

  • Today, phenol has been largely replaced by more effective phenol derivatives such as 4-hexylresorcinol. The compound 4-hexylresorcinol is an ingredient in many mouthwashes and throat lozenges
• The phenol derivatives o-phenylphenol and 2- benzyl-4-chlorophenolare the active ingredients in Lysol, a disinfectant for walls, floors, and furniture in homes and hospitals
• OCCURRENCE OF AND USES FOR PHENOLS• A number of phenols possess antioxidant activity.

  • An antioxidant is a substance that protects othersubstances from being oxidized by being oxidizeditself in preference to the other substances.

  • A naturally occurring phenolic antioxidant that isimportant in the functioning of the human body isvitamin E.
• A number of phenols found in plants are used as flavoring agents and/or antibacterials

  Thymol, obtained from the herb thyme, possesses both flavorant and antibacterial properties. It is used as an ingredient in several mouthwash formulations

  Eugenol is responsible for the flavor of cloves. Dentists traditionally used clove oil as an antiseptic because of eugenol’s presence

  Vanillin, which gives vanilla its flavor, is extracted from the dried seed pods of the vanilla orchid.
• SULFUR ANALOGS OF ALCOHOLS

  • Many organic compounds containing oxygen have sulfur analogs, in which a sulfur atom has replaced an oxygen atom.

  • Thiols, the sulfur analogs of alcohols, contain —SH functional groups instead of —OH functional groups. The thiol functional group is called a sulfhydryl group. A sulfhydryl group is the —SH functional group

  • A thiol is an organic compound in which a sulfhydryl group is bonded to a saturated carbon atom. An older term used for thiols is mercaptans