Carboxylic acids and derivatives Flashcards
What are carboxylic acids?
Organic acids with a carboxyl group, which has the formula -C(=O)OH, usually written -COOH or -CO2H.
They are Brownstead-Lowry acids (proton donors) that actually relatively weak. Salts and anions of carboxylic acids are called carboxylates
How is naming of carboxylic acids done?
By replacing the “e” of the corresponding alkane with “oic acid”. The molecule is numbered such that the carbonyl carbon is number one.
Many have common names as well:
- formic acid/methanoic acid
- ascetic acid/ethanoic acid
- carbonic acid/hydroxymethanoic acid
The hydrogen atom is weakly acidic in carboxylic acid, why is this?
Due to its attachment to the oxygen atom, and because the carboxylate anion is resonance stabilised
In carboxylic acids the carboxyl carbon is very susceptible to nucleophilic attack. Why?
Due to the attached oxygen atom, and the carbonyl oxygen, both atoms being electronegative
The relative acid strength among carboxylic acids depends on what?
The inductive effects of the attached groups
What are carboxylic acid derivatives?
A series of compounds that can be synthesised using carboxylic acid. For the GAMSAT this includes acid chlorides, anhydrides, amides, and esters
How are acid halides named?
By replacing the “ic acid’ of the parent carboxylic acid with the suffix “yl halide”.
E.g. butanoyl bromide
How are acid anhydrides named?
By replacing the “acid” of the parent carboxylic acid with the word “anhydride”.
E.g. acetic anhydride
How are amides named?
By replacing the “ic acid” of the parent anhydride with the suffix “amide”
E.g. propanamide
How are esters named?
First by citing the name of the alkyl group, followed by the parent acid, with the “ic acid” replaced by “ate”.
E.g. Methyl acetate
The salts of long chain carboxylic acids are called what?
Soaps
What is the type of ester which is biologically significant?
Fats
What is the resonance effect? Inductive effects?
The ability of the substituent to stabilise the carbocation intermediate by delocalisation of electrons.
The inductive effect is the substituent group, by virtue of its electronegativity, to pull electrons away increasing the partial positivity of the carbonyl carbon
What is steric or bulk hinderance?
Refers to when a reaction is impeded by the bulk or spatial arrangement of a molecule.
The less steric hinderance, the more access a nucleophile will have to attack the carbonyl carbon, and vice versa
