carbonyls, carboxylic acids and esters Flashcards
suffix for acyl chlorides
“-oyl chloride”
suffix for esters
“-oate”
carboxylic acid + alcohol —>
ester + water
acid hydrolysis of ester + conditions
reversible
ester + water <—> carboxylic acid + alcohol
using a hot aqueous acid (H2O/H+)
base hydrolysis of ester + conditions
irreversible
ester + OH- —-> carboxylate salt + alcohol
using a hot aqueous alkali (H2O/NaOH)
hydration with acyl chlorides
acyl chloride + water —> carboxylic acid + HCl
what does a nucleophilic reaction with NaBH4 and a carbonyl form and what is another name for this reaction?
an alcohol
reduction reaction
what does a nucleophilic reaction of a carbonyl with HCN form and how do you make HCN?
a hydroxynitrile
HCN made in situ: NaCN + H2SO4 ——> HCN + NaHSO4
what is the purpose of 2,4-DNP and what result do you get when it is added to a carbonyl?
2,4-DNP (2,4-dinitrophenylhydrazine) is used to detect the presence of a carbonyl
if a carbonyl is present, an orange precipitate will form
after using 2,4-DNP, how would you distinguish between 2 carbonyls? e.g 2 ketones
identify the melting point of the crystals and compare to a data book
how do you distinguish between an aldehyde and a ketone? (chemical test)
use Tollen’s (ammoniacal silver nitrate)
if an aldehyde is present, a silver mirror will form
explain the reaction between Tollen’s and an aldehyde in terms of oxidation and reduction
aldehyde is oxidised to carboxylic acid
silver ions are reduced to solid silver (ppt)
carboxylic acid suffix
“-oic acid”
explain the solubility of carboxylic acids
as the O-H/C=O groups in carboxylic acids are polar, it can form hydrogen bonds with water, so is soluble
carboxylic acids with up to 4 carbon atoms are soluble in water, but as the length of the carbon chain increases the non-polar bonds have more of an effect on the polarity of the molecule, so solubility decreases.
what kind of acids are carboxylic acids?
weak acids
carboxylic acid + metal = ?
what kind of reaction is this and what might you observe?
carboxylate salt + hydrogen
type of reaction: redox
observations: effervescence, metal disappears
carboxylic acid + metal oxide/alkali = ?
carboxylate salt + water
what might you observe when a carboxylic acid is added to an alkali?
there may not be any noticeable reaction as the two solutions react together to form an aqueous solution of the salt
carboxylic acid + carbonate = ?
what are the observations?
carboxylate salt + water + CO2
effervescence (CO2)
if carboxylic acid is in excess, the carbonate will dissolve
how do you distinguish a carboxylic acid from other organic compounds e.g. phenol?
it is the only organic compound sufficiently acidic enough to react with carbonates
what conditions are needed for an esterification reaction?
acid catalyst e.g H3PO4
making an acyl chloride
carboxylic acid + SOCl2 —-> acyl chloride + SO2(g) + HCl(g)
acyl chloride + alcohol/phenol —-> ?
ester + HCl
acyl chloride + 2NH3 —-> ?
primary amine + ammonium chloride
