Intermediate Topic 858 of 1102 Organic Chemistry
Qualitative Organic Tests
Bromine water for unsaturation, 2,4-DNP for carbonyls and iodoform for methyl ketones.
In-depth explanation of Qualitative Organic Tests
Qualitative organic tests use simple reagents to identify the functional groups in an unknown compound through characteristic colour changes or precipitates. Bromine water is decolourized by alkenes and alkynes through addition. Acidified potassium permanganate is decolourized by alkenes and by oxidizable alcohols. 2,4-Dinitrophenylhydrazine gives an orange precipitate with aldehydes and ketones, Tollens' reagent identifies aldehydes, iron(III) chloride gives violet with phenols, and sodium bicarbonate gives effervescence with carboxylic acids.
Going deeper: Qualitative Organic Tests
Key ideas: Use simple tests to identify functional groups: Br2 water or Baeyer for C=C, Lucas for alcohol class, FeCl3 for phenol (violet), Tollens and Fehling for aldehydes, 2,4-DNP for any aldehyde or ketone (orange precipitate), iodoform for methyl ketones, NaHCO3 for acid, carbylamine for primary amine, Hinsberg for amine class, ninhydrin for amino acids (purple). Always run a negative control.
Common mistakes and connections: Students use tests outside their scope, such as Lucas on phenols, or ignore interference from other groups. Another error is claiming a negative test proves absence when conditions were wrong. Links to every functional group topic and to planning identification flowcharts.
Worked example and use case
Iodoform reaction, Lucas test and sodium bicarbonate effervescence are all used to identify particular functional groups.
Frequently asked questions about Qualitative Organic Tests
What is Qualitative Organic Tests?
Bromine water for unsaturation, 2,4-DNP for carbonyls and iodoform for methyl ketones.
Is Qualitative Organic Tests a beginner, intermediate or advanced topic?
Qualitative Organic Tests is a intermediate topic in Organic Chemistry. It builds on the vocabulary of beginner topics in this area.
What should I learn before Qualitative Organic Tests?
Study these earlier topics in Organic Chemistry first: Aspirin Synthesis, Dyes and Pigments, Petrochemicals.
What comes after Qualitative Organic Tests?
The next topics in Organic Chemistry are Iodoform Reaction and Purification of Organic Compounds.
Can I practise Qualitative Organic Tests with quizzes?
Yes. The interactive lesson includes a self-check question on Qualitative Organic Tests, and the Organic Chemistry quiz draws on every topic in this area.
Where Qualitative Organic Tests fits in Organic Chemistry
Qualitative Organic Tests is topic 130 of 148 in Organic Chemistry.