Alcohol

• Alcohols


  The functional group is the hydroxyl group (-OH). The general structure is R-OH, where R represents any alkyl group.
• Phenols


  Special classes of alcohols where the R is an aromatic group. The general structure is Ar-OH, where Ar represents any aromatic group.
• Ethers


  Have two alkyl or aryl groups attached to an oxygen atom. The general structure is R-O-R', where R' again is any alkyl group.
• Thiols


  A family of compounds that contain the sulfhydryl group (-SH). The general structure is R-SH.
• Alcohols


  • The hydroxyl oxygen and the two atoms bonded to it are all in the same plane and have a bond angle of approximately 104o, similar to a water molecule
  • The hydroxyl group is polar, with a partial negative charge on the oxygen and a partial positive charge on the hydrogen
• Alcohols boil at higher temperature than alkanes of similar MW


  Due to hydrogen bonding
• Hydrogen bonding


  The strongest of the intermolecular forces, where a hydrogen atom bonded to an electronegative atom is attracted to an unshared electron pair on another small electronegative atom
• Solubility rule


  Like molecules dissolve like molecules. Polar substances are soluble in polar solvents, nonpolar substances are soluble in nonpolar solvents.
• Solubility of alcohols in water

  An organic compound is soluble in water if the Carbon to Oxygen ratio in the compound does not exceed 4:1.
• Solubility of alcohols in water

  • Methanol (infinitely soluble)
  • Ethanol (infinitely soluble)
  • Propanol (infinitely soluble)
  • Butanol (8.88 g/100 g H2O)
  • Pentanol (2.73 g/100 g H2O)
  • Hexanol (0.602 g/100 g H2O)
  • Heptanol (0.174 g/100 g H2O)
• Solubility of alcohols in water

  The hydroxyl group area is polar and hydrophilic, while the carbon chain is nonpolar and hydrophobic. As the carbon chain gets longer, the molecule becomes more nonpolar and less soluble in water.
• Alcohol nomenclature (IUPAC)


  1. Determine the name of the parent compound, the longest continuous carbon chain containing the -OH group.

  2. When the -OH group is present in a hydrocarbon, the -e ending of the alkane, alkene and alkyne is replace by -ol.

  3. The numbering is assigned such that the -OH group gets the lowest possible number.

  4. Alcohols containing two hydroxyl groups are named -diols. Those bearing three are called -triols. A number giving the position of each of the hydroxyl groups is needed in theses cases.

  5. If an alkene and an alkyne also contain the -OH group, the name is expressed as: if an alkene: ___-en___ol, if an alkyne: ___-yn___ol
• Common names of alcohols

  Derived from the alkyl group corresponding to the parent compound. e.g. 2-Propanol (isopropyl alcohol), Ethanol (ethyl alcohol)
• Common alcohols


  • Methanol, Ethanol, 2-Propanol (isopropyl alcohol), 1,2-Ethanediol (ethylene glycol), 1,2,3-Propanetriol (glycerol)
• Classification of alcohols


  1o alcohol: -OH bonded to a carbon which is bonded to one other carbon atom

  2o alcohol: -OH bonded to a carbon which is bonded to two other carbon atoms

  3o alcohol: -OH bonded to a carbon which is bonded to three other carbon atoms
• Phenols


  Compounds where the hydroxyl group is attached to the benzene ring. The general formula is Ar-OH, where Ar represents an aromatic group.
• Urushiols are dihydroxy phenols found in poison ivy and poison oak. They are oils secreted on the surface of the plant's leaves and cause the rash when transferred to skin.
• Many phenols are obtained by extraction from natural sources.
• Phenol


  A compound derived from benzene and used in resins, plastics, and pharmaceuticals and in dilute form as a disinfectant and antiseptic
• Other common phenols


  • Thymol [2-isopropyl-5-methylphenol] (mint; used in flavoring)
  • Carvarcol [5-isopropyl-2-methylphenol] (savory)
  • Butylated hydroxy toluene [2,6-di-tert-butyl-p-cresol](BHT; preservative)
  • Methyl salicylate
  • Urushiols (dihydroxy phenols found in poison ivy and poison oak)
• Urushiols


  Oils secreted on the surface of the plant's leaves and are easily transferred to clothing and skin when the leaves are touched. These are the guilty compounds which cause the rash!
• Naturally Occurring Phenols


  • Vanillin (found in vanilla beans, used as a flavoring for food)
  • Salicylic acid (used to prepare aspirin)
  • Resveratrol (found in grapes and peanuts, may be an anti-cancer agent)
  • Cyanidin (a very abundant compound belong to the flavone class of compounds, responsible for the red coloring in roses)
• Ethers


  A class of organic compounds that contain an oxygen between two alkyl groups. They have the formula R-O-R', with R's being the alkyl groups. These compounds are used in dye, perfumes, oils, waxes and industrial use.
• Aliphatic ether


  An ether in the molecule of which there are no aryl groups on the ether group
• An ether molecule may contain aryl groups, nevertheless, be an aliphatic ether
• Common Alkyl and Alkoxy Groups

  • Methyl
  • Ethyl
  • Propyl
  • Butyl
  • Methoxy
  • Ethoxy
  • Propoxy
  • Butoxy
• Naming format for ethers

  ALKOXYALKANE - The smaller, shorter alkyl group becomes the alkoxy substituent. The larger, longer alkyl group side becomes the alkane base name. Each alkyl group on each side of the oxygen is numbered separately. The numbering priority is given to the carbon closest to the oxgen. The alkoxy side (shorter side) has an "-oxy" ending with its corresponding alkyl group.
• Examples of ethers


  • CH3CH2OCH2CH3, diethyl ether (sometimes referred to as ether)
  • CH3OCH2CH2OCH3, ethylene glycol dimethyl ether (glyme)
• Common names for simple ethers

  The alkyl groups bonded to the oxygen are named in alphabetical order followed by the word "ether". Many simple ethers are symmetrical, in that the two alkyl substituents are the same. These are named as "dialkyl ethers".
• Heterocyclic ethers


  In cyclic ethers (heterocycles), one or more carbons are replaced with oxygen. Often, it's called heteroatoms, when carbon is replaced by an oxygen or any atom other than carbon or hydrogen. In this case, the stem is called the oxacycloalkane, where the prefix "oxa-" is an indicator of the replacement of the carbon by an oxygen in the ring.
• IUPAC names for ethers

  • Ethoxy ethane (diethyl ether)

  2. 2-ethoxy-2-methyl-propane

  3. cis-1-ethoxy-2-methoxycyclopentane

  4. 1-ethoxy-1-methylcyclohexane

  5. oxirane

  6. 2,2-dimethyloxirane
• Thiols


  Any organosulfur compound of the form R−SH, where R represents an alkyl or other organic substituent. The –SH functional group itself is referred to as either a thiol group or a sulfanyl group. Thiols are the sulfur analogue of alcohols (that is, sulfur takes the place of oxygen in the hydroxyl group of an alcohol)
• Thiols


  Many thiols have strong odors resembling that of garlic, onions or rotten eggs. Thiols are used as odorants to assist in the detection of natural gas (which in pure form is odorless), and the "smell of natural gas" is due to the smell of the thiol used as the odorant. Thiols are sometimes referred to as mercaptans.
• Thiol nomenclature


  The rules for naming thiols are exactly like those for alcohols, except that the suffix -ol is replaced by -thiol. The SH group is called a sulfhydryl function, but organic compounds containing the SH are called thiols in the IUPAC system, or called mercaptans in older nomenclature.
• Examples of thiols


  • Methanethiol

  Thiophenol

  Ethanedithiol

  1. buten-1-thiol