Alcohols Flashcards
what functional group do alcohols contain?
the hydroxyl functional group
what is meant by the term functional group?
Atom/group of atoms that give molecules their characteristic for reactions
What is the general formula for aliphatic alcohols with one OH group only?
CnH(2n+2)O
what are phenols?
Aromatic alcohols
Where is the OH group attached to on phenol?
alcohol group directly attached directly to the benzene ring
why can alcohols make hydrogen bonds with water molecules and with each other?
because they have H bonded to electronegative O
What does hydrogen bond between alcohol molecules do?
reduces their volatility (the ease of conversion from liquid to gas)
what the more OH groups that alcohol has result in?
The more hydrogen bonds it can form and the lower of volatility
why do alcohols have a tendency to be water soluble?
Because they can form hydrogen bonds
what does solubility decrease with?
Solubility decreases as the hydrocarbon chain increases
what causes solubility to decrease as the hydrocarbon chain increases is size?
The OH group has less influence and the solubility (lack of) of the longer hydrocarbon chain beccomes more dominant
What is a primary alcohol?
The -OH group is attached to a C with at least two H atoms on it and one alkyl group
What are secondary alcohols?
The -OH group is attached to a carbon atom with only one H atom on it and two alkyl groups.
what are tertiary alcohols?
The -OH group is attached to a carbon atom with no H atoms on it and three alkyl groups.
what are the four types of chemical reactions of the alcohols?
-Combustion
-Dehydration
-Substitution
-Oxidation
What is combustion of alcohol?
like organic materials, alcohols burn in excess oxygen to produce carbon dioxide and water
What does the term dehydration mean?
to remove water from one molecule
what is a good dehydrating agent?
Concentrated sulphuric acid or concentrated phosphoric acid
what are the conditions for dehydration of alcohol?
Heat under reflux
What does dehydration make?
An Alkene
Why is dehydration described as elimination?
because H and OH are being taken out from two adjacent c atoms to make water
what is substitution reactions of alcohol?
-Alcohols can form when you react with hydrogen halide
-The hydrogen halide is generated in place
what is an example of substitution reactions of alcohol?
An alcohol is heated, under reflux, in the presence of sodium chlorine and dilute sulphuric , hydrogen chloride forms in situ (in place)
Why do chemical reactions usually need to be heated?
in order to overcome activation energy and increase the rate of reaction
