Chapter 14 Alcohols Flashcards
what is an alcohol
an organic compound with the OH (hydroxyl) functional group
what are the two ways to name an alcohol
-ol suffix
hydroxy- prefix
what is the general formula for an alcohol
CnH2n+1OH
what does polyhydric mean
multiple alcohol functional groups attached
what is the shape and bond angle of the OH functional group when bonded to a carbon
bent
104.5
what is vital when drawing the skeletal formula of an alcohol
the bond from the carbon must be drawn to the oxygen not the hydrogen
why are alcohols normally water soluble
> O-H is polar due to big difference in electronegativity
>this allows the H in the OH to hydrogen bond to the O in H2O
why do long chain alcohols not normally dissolve in water
since the carbon chain is so long a large part of the organic compound is hydrophobic
what can help increase the solubility of an alcohol
adding more OH groups along the chain
what two physical properties other than solubility do the hydrogen bonds allow the alcohol to have
high melting point
high boiling point
what two reactions can take place to form alcohols
hydration of alkenes
fermentation of alkenes
what are the three conditions required for the hydration of alkenes to form alcohols
> 100C temp
high pressure
acidic catalyst (phosphoric acid)
why do alcohols produce a blue flame when combusted
the OH group means that the compound is already partially oxidised so burns well
what does [O] represent
an oxidising agent
what are the products of an oxidation of alcohol reaction dependent on
whether the alcohol is primary, secondary, tertiary
what happens when a primary alcohol is oxidised
initially an aldehyde is produced as long as the solution is distilled immediately along with water. if continuously heated (refluxed) a carboxylic acid is produced
what can you use to determine what type of organic compound the solution is
find the boiling point which acts as a diagnostic
aldehyde has the lowest and carboxylic acids the highest
what is a reflux reaction
when you heat something more strongly with an excess of an oxidising agent
what happens when a secondary alcohol is oxidised
the alcohol is refluxed to produce a ketone and water
what happens when you try to oxidise a tertiary alcohol
tertiary alcohols can’t be oxidised so no reaction takes place
what is the oxidising agent that is normally used
acidified dichromate(VI) (Cr2O7)^2-/H+
what observation can be made when an oxidation of an alcohol reaction takes place
the acidified dichromate makes the solution orange to begin then turns green when the chromium is reduced to Cr3+
why do aldehydes have the lowest boiling point
it only has induced dipole-dipole intermolecular bonds
why do alcohols have the middle boiling point
their OH allows for hydrogen bonding intermolecular forces
