Carbonyl Compounds Flashcards
Give the Tollen’s reagent half equation for when it forms a silver mirror and the Fehling’s one for a brick red precipitate.
Ag(NH3)2+ + e- –> Ag + 2NH3
Cu2+ + e- –> Cu+
Give the main reducing agent used for reducing aldehydes and ketones, and give an equation using [H].
NaBH4
RCHO + 2[H] —> RCH2OH
Draw the nucleophilic addition reaction between H- ions and an aldehyde, and CN- ions and an aldehyde. Name the products.
Self assess
How do you name esters?
- thyl = last bit
- oate = first bit
Name the oxidising agent for aldehydes and ketones, and the products formed from primary/secondary/tertiary alcohols. Then write an equation using [O] to show the oxidisation of an aldehyde.
Acidified potassium dichromate Primary alcohol -> aldehyde -> carboxylic acid Secondary alcohol -> ketone --X Tertiary alcohol --X RCHO + [O] --> RCOOH
Write the equation for the reaction between ethanoic acid and sodium carbonate, and an equation for ethanoic acid and sodium Hydrogencarbonate.
2CH3COOH + Na2CO3 –> 2CH3COONa + H2O + CO2
CH3COOH + NaHCO3 –> Ch3COONa + H2O + CO2
Give the general equation for an esterification reaction and catalyst.
RCOOH + ROH –[H+]–>RCOOR + H2O
Usually conc sulphuric acid used
Give three useful properties of esters.
They have pleasant smells - used for food flavourings
They are polar liquids and have low boiling points so are used as solvents.
Used as plasticisers to make plastics more flexible.
Give the general equations for acid and base hydrolysis of esters.
RCOOR + H2O –[H+]–> RCOOH + ROH
RCOOR + OH- —> RCOO- (carboxylate ion) + ROH
What are the monomers of fats/oils?
What is the formula of glycerol?
Fatty acids/glycerol
Propane 1,2,3 triol
Give the general equation for the hydrolysis of a fat with sodium hydroxide.
H2C-O-CO-R + 3NaOH —> glycerol + 3CH3RCOONa
HC-O-CO-R
H2C-O-CO-R
Give the biodiesel equation and catalyst
H2C-O-CO-R + 3CH3OH —-[KOH]—> glycerol + RCOOCH3
HC-O-CO-R
H2C-O-CO-R
Why may biodiesel not be carbon neutral?
CO2 released through combustion of biodiesel is absorbed by photosynthesis of plants.
However energy is used to make fertiliser, harvesting, and converting the oil. This energy is from fossil fuels combustion.
Draw the mechanisms of ethanoyl chloride with water, ammonia, an alcohol, and an amine. What is the mechanism called? Do the same for ethanoic anhydride.
Nucleophilic addition - elimination.
Self mark.
What are the benefits of using an acid anhydride instead of acyl chlorides?
Less vigorous reaction, no HCl formed, but ethanoic acid. anhydride cheaper than acyl chloride.
