6.41 - Alcohols and some of their reactions Flashcards
What are alcohols?
A homologous series, with general formula CnH2n+1OH
What is an easy way of imagining alcohols?
They are the same as alkanes, but one of the hydrogen atoms is replaced by a hydroxyl group
How can any alcohol be written simply?
ROH, because R can represent any alkyl group
How do you name an alcohol?
The number in the middle of the name is the lowest number carbon that the OH group is attached to. The naming system is then the same as alkanes
What is a primary alcohol?
An alcohol where the carbon with the OH group is bonded to one other carbon atom only
What is a secondary alcohol?
An alcohol where the carbon with the OH group is bonded to two other carbon atoms
What is a tertiary alcohol?
An alcohol where the carbon with the OH group is bonded to three other carbon atoms
What happens during the complete combustion of an alcohol?
The normal products, carbon dioxide and water, are formed
What is the name given to the process that converts alcohols to halogenoalkanes?
Halogenation
What is the method for chlorination of an alcohol?
- Add Phosphorus (V) Chloride to the alcohol
- This forms a halogenoalkane, phosphorus oxychloride (POCl3) and hydrogen chloride
CH3CH2CH2OH + PCl5 -> CH3CH2CH2Cl + POCl3 + HCl
What is an alternative chlorination method for tertiary alcohols?
Shaking the alcohol with concentrated hydrochloric acid
How is bromination conducted?
- Hydrogen bromide is formed by mixing potassium bromide and sulfuric acid
- The HBr is then added to the alcohol, forming the halogenoalkane and water
What is the iodination method?
- Red phosphorus and iodine are mixed, to form phosphorus (III) iodide
- This is then heated under refulx with the alcohol, forming phosphonic acid as a side product
How can alcohols be dehydrated?
By heating them with concentrated phosphoric acid
Whay are dehydration reactions named as such?
Because water is the only product formed - water os removed from the alcohol
