CAIE A-Level Chemistry AS 17.1.4.2.4 Dnph Carbonyl Test Questions

Practise the CAIE 9701 2,4-dinitrophenylhydrazine test, recording the yellow, orange or red precipitate that confirms an aldehyde or ketone carbonyl.

Exam points

add 2,4-dinitrophenylhydrazine reagent to the unknown organic liquid or solution
record a yellow, orange or red precipitate as a positive result for an aldehyde or ketone C=O group
state that 2,4-DNPH confirms a carbonyl but does not by itself distinguish aldehyde from ketone

[Maximum number: 1]

$4\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCHO}$ is used in the synthesis of some antibiotics.

X, Y and Z are all isomers of $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCHO}$ .

A summary of some of the reactions and properties of X, Y and Z is shown in the table.

Table for Question CAIE A-Level Chemistry AS 17.1.4.2.4 Dnph Carbonyl Test Questions question 1 — CAIE A-Level Chemistry AS

X and Y each contains a carbonyl group.

Complete the table with the expected observations for the reactions of X and Y with 2,4-DNPH.

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CAIE A-Level Chemistry AS 17.1.4.2.4 Dnph Carbonyl Test Questions question 1