Carbonyl Compounds

Organic compound X has the empirical formula $\text{C}_2\text{H}_4\text{O}$.

Compound X is reduced by $\text{LiAlH}_4$, but not by $\text{NaBH}_4$.

What is compound X?

Options

A   ethanoic acid
B   ethanal
C   butan-1-ol
D   butanoic acid

What is the mechanism of the reaction of hydrogen cyanide with propanone?

Options

A   electrophilic addition
B   electrophilic substitution
C   nucleophilic addition
D   nucleophilic substitution

Compound T is tested with three reagents and gives the results shown.

What is compound T?

Options

A   $(\text{CH}_3)_2\text{CHCHO}$
B   $(\text{CH}_3)_2\text{CHCH}_2\text{OH}$
C   $\text{CH}_3\text{CH(OH)COCH}_3$
D   $(\text{CH}_3)_2\text{CHCOCH}_3$

Complete combustion of compound T produces carbon dioxide and water only. Compound T produces steamy fumes with $\text{PCl}_5$. Compound T does not give any visible product with 2,4-dinitrophenylhydrazine reagent.

What can be deduced with certainty from this information?

Options

A   Compound T is a carboxylic acid.
B   Compound T is a hydrocarbon.
C   Compound T is an alcohol.
D   Compound T is not an aldehyde.

Information about carbonyl compound X is given.

• Compound X reacts with $\text{LiAlH}_4$ to produce a secondary alcohol.
• Compound X reacts with alkaline $\text{I}_2(\text{aq})$ to give a yellow precipitate.

What is compound X?

Options

A   butanal
B   butanone
C   ethanal
D   pentan-3-one

Methanoic acid, $\text{HCO}_2\text{H}$, has acidic properties similar to those of other carboxylic acids. In addition, it can be oxidised by the same oxidising agents that are capable of oxidising aldehydes.

Which pair consists of two compounds that will give the same observations with Fehling’s reagent?

Options

A   $\text{HCO}_2\text{H}$ and $\text{CH}_3\text{CO}_2\text{H}$
B   $\text{HCO}_2\text{H}$ and $\text{CH}_3\text{CO}_2\text{CH}_3$
C   $\text{HCO}_2\text{H}$ and $\text{CH}_3\text{CH}_2\text{COCH}_3$
D   $\text{HCO}_2\text{H}$ and $\text{CH}_3\text{CH}_2\text{CHO}$

Butan-2-one reacts with alkaline $\text{I}_2(\text{aq})$. An excess of dilute sulfuric acid is then added to the reaction mixture.

The organic products of this reaction sequence are triiodomethane and product M.

What is product M?

Options

A   ethanoate ion
B   ethanoic acid
C   propanoate ion
D   propanoic acid

Ethanal reacts with KCN dissolved in liquid HCN. This reaction involves the formation of an intermediate.

Which statement is correct?

Options

A   HCN does not have any lone pairs of electrons and so $\text{CN}^-$ is the catalyst.
B   The $\text{O}^{\delta-}$ of C=O attacks $\text{K}^+$ in a nucleophilic attack.
C   A proton from HCN is transferred to the intermediate.
D   The reaction is a nucleophilic substitution.

What is formed when propanone is heated under reflux with a solution of $\text{NaBH}_4$?

Options

A   propan-2-ol
B   propan-1-ol
C   propanal
D   propane

Compound P displays cis/trans isomerism and gives a red-brown precipitate with Fehling’s solution.

What is P?

Options