alcohols Flashcards
what is the functional group of alcohols
O-H
general formula
Cn H2n+1 OH
What makes alcohol molecules polar
the presence of the highly electronegative oxygen atoms- gives rise to intermolecular bonding
why do alcohols have unusual physical properties
because of the hydrogen bonding, gives it high Tb and Tm and water solubility
partial oxidation of alcohols
PRIMARY + [O]=
aldehyde
PRIMARY + 2[O] =
Carboxylic acid
SECONDARY ALCOHOL+ [O]=
KETONE
TERTIARY ALCOHOL
NO reaction
what is the ideal oxidising agent
K2Cr2O7 dissolved in dilute H2SO4
when the reaction occurs, what is seen
a colour change from orange to green
Making Aldehydes
excess primary alcohol is warmed with K2Cr2O7 and diluted H2SO4 in a simple distillation apparatus:
why is distillation used to make aldehydes
to ensure that the aldehyde produced does not get further oxidised to a carboxylic acid.
aldehydes have low Tb so as they form, they boil and escape the oxidising agent
which apparatus do you use to make ketones and carboxylic acids
REFLUX
- any vapours formed in the flask are cooled and liquefied by the vertical condenser and fall back under gravity.
- this means that full reaction can occur- any aldehydes are trapped inside with oxidising agent, forming carboxylic acids
dehydration of alcohols
concentrated H2SO4 is a powerful dehydrating agent
removes a water molecule from an alcohol to form an alkene + H20
-known as ELIMINATION REACTION
