• The -OH (alcohol) functional group makes the molecule polar enough to hydrogen bond
  • Making it water soluble
• It’s a fermentation product but vulnerable to further oxidation to aldehyde or an acid
• A hydrogen on the alkane is replaced by the hydroxyl (-OH) group
• Alcohols are also classified according to the carbon the hydroxyl is directly attached to
• Properties of Alcohol
  • High boiling point
  • Soluble in water
  • Polar compounds

Naming Alcohols

• Drop the “e” and add the suffix “-ol” to the parent chain

  • 2,4 - Pentandio

  

Voice Notes:

• The more “OH” you add, makes it more polar
• Alcohols can be main or side chain

TEXTBOOK READINGS pg. 38-44

Alcohols and ethers are structurally similar in that they are essentially water molecules with substituted alkyl groups. In alcohols, one of the two H atoms in H2O is replaced by an alkyl group; in ethers, both H atoms are replaced by alkyl groups.

1°, 2°, and 3° Alcohols

• Review notes on Primary, Secondary, and Tertiary organic halides!

  Functional Groups

  • Same idea, just with alcohols!

• This classification is important for predicting reactions each alcohol will undergo, because the rxns and products are determined by the availability of H atoms or Alkyl groups in key positions

  • Therefore, it’s useful in the selection of starting materials for a multistep rxn sequence to synthesize a final product

Cyclic Alcohols

• An alcohol that contains an alicyclic ring
• Aromatic Alcohols
  • Aromatic compounds that have attached -OH groups
• The simplest aromatic alcohol is a benzene ring with one attached OH group; it is named hydroxybenzene, also called phenol.
• When naming cyclic or aromatic alcohols, the OH (hydroxyl) groups may be considered as groups attached to the parent ring. Thus, phenol is named hydroxybenzene. A benzene ring with two hydroxyl groups adjacent to each other is named 1,2-dihydroxybenzene.

Properties of Alcohols

• They have boiling points that are much higher than their parent alkanes
  • This is due to the hydroxyl group attached to a hydrocarbon chain
  • This makes the alcohol molecules more polar and gives them the capacity to form hydrogen bonds
  • Simple alcohols are much more soluble in polar solvents than are their parent alkanes
• In long-chain alcohols, the hydrocarbon portion of the molecule is nonpolar, making larger alcohols good solvents for nonpolar molecular compounds as well. Thus, alcohols are frequently used as solvents in organic reactions because they will dissolve both polar and nonpolar compounds.
• When one of the H atoms in water is replaced by an alkyl group, the resulting alcohol, ROH, is less polar than water, with accompanying differences in physical properties.

Combustion of Alcohols

Like hydrocarbons, alcohols undergo complete combustion to produce only carbon dioxide and water

Polyalcohol's

• An alcohol that contains more than one hydroxyl functional group
• We use the prefixes ‘-diol’ and ‘-triol’ to the entire alkane name to indicate two and three -OH groups
• The hydroxyl groups in an alcohol can also be considered an added group to a parent hydrocarbon chain; the prefix for the hydroxyl group is hydroxy-.

Naming Alcohols

1. Identify the longest C chain
2. Look at where the hydroxyl groups are attached
3. Look to see where any other group(s) are attached
4. Lastly determine if it is a primary, secondary, or tertiary alcohol

Drawing Alcohols

1. Write the C skeleton for the “parent” molecule
2. Attach an -OH group to the correct C atoms
3. Complete the remaining C bonds with H atoms

Preparing Alcohols: Hydration Reactions

• During reactions of alkenes, the double bonds readily undergo addition reactions. If we start with an alkene, we can introduce the OH functional group by adding HOH, water.
• Many alcohols are prepared industrially by addition reactions of water to unsaturated hydrocarbons.
  • Since the overall result is the addition of a water molecule, this type of addition reaction is also referred to as a hydration reaction
  • The hydrogen attaches to the carbon atom that already has more hydrogen atoms; the OH group attaches to the other carbon atom in the double bond.

From Alcohols to Alkenes: Elimination Reactions

• Under certain conditions alcohols decompose to produce alkenes and water.
• This type of reaction is catalyzed by concentrated sulfuric acid, which removes a hydrogen atom and a hydroxyl group from neighbouring C atoms, leaving a CC double bond.
• Since this elimination reaction results in the removal of water, this type of reaction is also called a dehydration reaction.