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Alcohols, Phenols, and Ethers Alcohol – has an –OH group (hydroxy) attached to a saturated alkane. General formula R-OH. Phenol – has an –OH group on a benzene ring. Ether – a compound that has the functional group. Naming Alcohols
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Alcohols, Phenols, and Ethers Alcohol – has an –OH group (hydroxy) attached to a saturated alkane. General formula R-OH. Phenol – has an –OH group on a benzene ring. Ether – a compound that has the functional group
Naming Alcohols Step 1: Name the longest chain to which the –OH group is attached. Use the alkane name of the chain, drop the –e ending, and replace it with –ol. Step 2: Number the longest chain to give the lowest number to the carbon with the –OH. Step 3: Locate the –OH position. Example: OH | CH3—CH2—CH2—CH—CH2—CH3 6 5 4 3 2 1 3-hexanol
CH3 | OH | CH3 | Naming Alcohols, cont. Step 4: Locate and name any other groups attached to the longest chain. Step 5: Combine the name and location of other groups, the location of the –OH, and the longest chain into the final name. Example: CH3—CH2—CH2—CH—CH—CH3 6 5 4 3 2 1 2,4-dimethyl-3-hexanol
Physical Properties of Alcohols, cont. The –OH group can hydrogen bond between alcohol molecules leading to relatively high boiling points. Hydrogen bonding in pure ethanol:
Physical Properties of Alcohols The –OH group is polar and capable of hydrogen bonding. This makes low molecular weight alcohols highly soluble in water. Hydrogen bonding in a water-methanol solution:
Physical Properties of Alcohols, cont. Larger alkanes have greater hydrophobic regions and are less soluble or insoluble in water. Water interacts only with the –OH group of 1-heptanol:
Alcohol Reactions The removal of water (dehydration) from an alcohol is an elimination reaction and produces an alkene.
Alcohol Reactions, cont. Primary alcohol oxidation Secondary alcohol oxidation
Properties of Ethers Much less polar than alcohols. Low boiling and melting points because of the inability to hydrogen bond between molecules. More soluble in water than alkanes, but less soluble than alcohols.
Hydrogen bonding of dimethyl ether: (a) with water and (b) no hydrogen bonding in the pure state: