Alcohols and Ethers

1. Alcohols and Ethers Chemistry 122

2. Alcohols • An alcohol is an organic compound that contains the functional group – OH (hydroxyl) • They can be organized into groups depending on the number of R groups attached to the carbon with the hydroxyl group • If only 1 R group is attached, it is a primary alcohol • 2 R groups = secondary alcohol • 3 R groups = tertiary alcohol

3. Naming Alcohols Both IUPAC and common names exist When using the IUPAC naming system, both straight-chain as well as substituted alcohols require dropping the ending of “e” and adding the suffix “-ol” When identifying the numbering of carbon from the continuous chain, give the lowest number to the carbon attached to the hydroxyl group Alcohols containing more than one hydroxyl group are named diols, triols, and tetrols…

4. Common Names of Alcohols • Similar to the naming system of halocarbons • The alkyl group associated with the parent chain is identified, following by the word ‘alcohol’ • Compounds with more than one hydroxyl group are called glycols • Phenols are those alcohol compounds that contain an aromatic ring • It is the parent compound • Cresol is the common name for o, m, and p positions within a ring

5. Properties of Alcohols • Capable of intermolecular hydrogen bonding • They are derivatives of water (hydroxyl comes from water), they are somewhat soluble • Alcohols that contain up to four carbons are completely soluble (because they form hydrogen bonds with water); those containing more than four have much lower solubilities • The carbon chain is not polar so not attracted to water; the hydroxyl group is polar and so, attracted to water

6. Uses of Alcohol • Antiseptic • Used as a base for cosmetics • Present in anti-freezes • Ethyl alcohol is an important industrial chemical • Derived from the fermentation of sugar through the action of yeast or bacteria • Ethanol used in labs has been denatured by adding methyl alcohol

7. Addition Reactions • The double bonds that exist between carbon can be easier to break than single covalent bonds • As a result, it is possible for a reaction to occur from an alkene or even alkyne • This advantage allows other functional groups to attach to carbon-based compounds • The addition of water to an alkene is called a hydration reaction • A strong acid, usually HCl, is used as a catalyst

8. Other types of reactions… When a halogen reacts with an alkene, the product is a disubstituted halocarbon Hydrogen halides can also react with alkenes – which produces a monosubstituted halocarbon The addition of hydrogen to an alkene to produce an alkane (or halocarbon) is called a hydrogenation reaction

9. Ethers An oxygen bonded to two carbon groups is called an ether Its general structure is R – O – R The alkyl groups attached are named alphabetically followed by the word ether When both R groups are the same, the ether is said to be symmetric The prefix di- is often used but can be dropped

10. Properties of Ethers Low boiling points compared to alcohols but higher than the boiling points of hydrocarbons and halocarbons. More soluble in water than hydrocarbons and halocarbons but less than alcohols Section Review 23.2, questions 7 – 12, p. 736