Reactions of Carboxylic Acids + Esters
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When a compound loses an H+ ion, what behaviour is it showing?
It is acting as an acid by donating a proton
Why does the delocalisation of carboxylic acid make the resulting ion, the carboxylate ion, more stable? (ngtve. chrg. shrd. ovr. O + C crbylt. ion. - inc. stbly.)
The negative charge is shared over the two oxygen atoms and the carbon in the carboxylate ion, increasing stability
What reaction distinguishes carboxylic acids from other organic compounds, especially those with -OH groups? (like alcohols)
Carboxylic acids reacting with a hydrogencarbonate or metal carbonate causing the release of carbon dioxide
What are the compounds which react with a carboxylic acid in order to form carbon dioxide (CO2)? (carbonates)
Either sodium hydrogencarbonate (NaHCO3), both in aqueous and solid conditions or solid sodium carbonate (Na2CO3)
What observation is made when a carboxylic acid reacts with a carbonate?
Effervescence (bubbling) due to CO2 gas being released
Show the formation of a carboxylate ion when the hydrogen atom is removed from the -OH group of the carboxylic acid
RCOOH –> RCOO’ + H+
Outline the equation for the reaction involving ethanoic acid reacting with sodium hydrogencarbonate
CH3COOH (aq) + NaHCO3 (aq) —-> CH3COONa (aq) + H2O (l) + CO2 (g)
How do carboxylic acids behave in acid - base reactions?
They act as proton donors, showing the typical reactions of acids
What types of substances do carboxylic acids react with to form salts?
• metal oxides • metal carbonates • metals • metal hydroxides
What are the salts formed from carboxylic acids called?
They are called carboxylates
How are carboxylate salts named? Use methanoic acid and ethanoic acid as an example
They are named after the parent acid (carboxylic acid), using the suffix -oate at the end of methanoic acid = methanoate ethanoic acid = ethanoate
General formula of an ester?
RCOOR’, where R and R’ are alkyl or aryl groups
Two ways esters are formed?
Carboxylic acids react with alcohols to form esters + water in a condensation reaction Acid anhydrides react with alcohols to form carboxylic acids and esters
Catalyst used in ester formation?
A strong acid, typically concentrates sulfuric acid (H2SO4)
What happens during acid hydrolysis of an ester? (E hydlsd. aftr. rctng. w/ wtr. frm. A + CA rctn. ctlysd. stng. )
Eester is hydrolysed after reacting with water to form an alcohol and carboxylic acid, reaction is catalysed by a strong acid like H2SO4
Outline the acid hydrolysis of ethyl ethanoate Name each product
CH3COOCH2CH3 + H2O —–> CH3COOH + CH3CH2OH Ethanol + ethanoic acid
What happens during base hydrolysis of an ester? (E rflxd. w/ dlte. alk. frm. crbly. slt. )
The ester is refluxed with a dilute alkali (NaOH) to form a carboxylate salt and an alcohol
Outline the base hydrolysis of methyl propanoate
CH3CH2COOCH3 + NaOH ——-> CH3CH2COONa + CH3OH Sodium propanoate + methanol
Why is base hydrolysis considered better than acid hydrolysis? (bse. hydlys. irr. - >prdct. frmd, prdcts. frmd. esr. sprt. snc. A dstld. off)
Base hydrolysis is irreversible, so more product is formed. The products formed are easier to separate since the alcohol can be distilled off
Fill in the table outlining the features of each acid/base hydrolysis • Reaction type • Conditions • Catalyst/Reagent • Products formed • Extent of reaction • Ease of separation of product
Compare your answer to the completed table
When a carboxylic acid reacts with a salt, what is formed?
Salt + Hydrogen
Outline the equation when methanoic acid (HCOOH) reacts with sodium (Na)?
HCOOH + Na —> HCOONa + 1/2 H2
When a carboxylic acid reacts with a metal oxide, what is formed?
Salt and water
What is formed when methanoic acid (HCOOH) reacts with sodium oxide (Na2O)?
2HCOOH + Na2O —> 2HCOONa + H2O