Chemistry > Practical Organic Chemistry > 1.0 Detection of Elements in Organic Compound
Practical Organic Chemistry
1.0 Detection of Elements in Organic Compound
1.1 Detection of carbon and Hydrogen
1.2 Detection of Nitrogen, Halogens and Sulphurl
1.3 Detection of Nitrogen
1.4 Soda lime test for nitrogen
1.5 Detection of Halogens
1.6 Layer test for bromine and iodine
1.7 Detection of Sulphur
1.8 Test of halogen present in the ionic form
1.9 Detection of sulphur present in the side chains
1.10 Detection of Oxygen
2.0 Summary of Solubilitiy Behaviour
2.1 Compounds soluble in both water and ether
2.2 Compounds soluble in water but insoluble in ether
2.3 Compounds insoluble in water, but soluble in dilute sodium hydroxide
2.4 Compounds insoluble in water, but soluble in dilute hydrochloric acid
2.5 Water-insoluble hydrocarbons and oxygen compounds that do not contain N or S and are soluble in cold concentrated sulphuric acid
2.6 Compounds, not containing N or S, insoluble in concentrated sulphuric acid
2.7 Compounds that contain $N$ or $S$ which are not in groups 1-4
3.0 Detection of Functional Group
3.1 Test for Alcoholic Hydroxyl Group
3.2 Test Phenolic Hydroxyl Group
3.3 Test of Aldehyde and Ketonic Groups
3.4 Test for Aldehydic Group
3.5 Test for Ketonic Group
3.6 Tests for Carboxylic Group
3.7 Test for Primary Amine Group
3.8 Test for Secondary Amino Group
3.9 Test for Nitro Group
4.0 Methods of Separation of Mono-functional Organic Compounds from Binary Mixtures
5.0 Separation based on Differences in the volatilities of the component in aqueous solution
6.0 Determination of Empirical Formula and Molecular Formula
7.0 Solved Example (Subjective)
1.3 Detection of Nitrogen
1.2 Detection of Nitrogen, Halogens and Sulphurl
1.3 Detection of Nitrogen
1.4 Soda lime test for nitrogen
1.5 Detection of Halogens
1.6 Layer test for bromine and iodine
1.7 Detection of Sulphur
1.8 Test of halogen present in the ionic form
1.9 Detection of sulphur present in the side chains
1.10 Detection of Oxygen
2.2 Compounds soluble in water but insoluble in ether
2.3 Compounds insoluble in water, but soluble in dilute sodium hydroxide
2.4 Compounds insoluble in water, but soluble in dilute hydrochloric acid
2.5 Water-insoluble hydrocarbons and oxygen compounds that do not contain N or S and are soluble in cold concentrated sulphuric acid
2.6 Compounds, not containing N or S, insoluble in concentrated sulphuric acid
2.7 Compounds that contain $N$ or $S$ which are not in groups 1-4
3.2 Test Phenolic Hydroxyl Group
3.3 Test of Aldehyde and Ketonic Groups
3.4 Test for Aldehydic Group
3.5 Test for Ketonic Group
3.6 Tests for Carboxylic Group
3.7 Test for Primary Amine Group
3.8 Test for Secondary Amino Group
3.9 Test for Nitro Group
To a little sodium extract (Lassaigne solution) we add freshly prepared ferrous sulphate solution. The solution is made alkaline and heated. On addition of. ${H_2}S{O_4}$ if a green or blue colour appears, nitrogen is present. If no appearance of colour, add a little ferric ion solution. A blue or green colour of ferric ferrocyanide confirms nitrogen \[FeS{O_4} + 2NaOH\;\xrightarrow{{}}\;\mathop {Fe{{(OH)}_2}}\limits_{(Green\;ppt.)} \downarrow \; + \;N{a_2}S{O_4}\]\[Fe{(OH)_2} + 6NaCN\;\xrightarrow{{}}\;\mathop {N{a_4}[Fe{{(CN)}_6}]}\limits_{Sodium\;ferrocyanide} \; + \;2NaOH\]\[3N{a_4}[Fe{(CN)_6}]\; + \;2F{e_2}{(S{O_4})_3}\;\xrightarrow{{}}\;F{e_4}{[Fe{(CN)_6}]_3} + 6N{a_2}S{O_4}\]
or\[2N{a_4}[Fe{(CN)_6}]\; + \;4FeC{l_3}\xrightarrow{{}}\;\mathop {\mathop {F{e_4}{{[Fe{{(CN)}_6}]}_3}}\limits_{Ferric\;ferrocyanide} }\limits_{(Blue)} + 12NaCl\]
If the compound contains both nitrogen and sulphur then there will be sodium sulpho or thiocyanide in the sodium extract. This on addition of $FeC{l_3}$ will produce a red colour of ferric sulphocyanide. \[Na\; + \;S\; + \;C\; + \;N\;\xrightarrow{{}}\;NaSCN\]\[3NaSCN\; + \;FeC{l_3}\xrightarrow{{}}\;\mathop {\mathop {Fe{{(SCN)}_3}}\limits_{{\text{Ferric sulphocyanide}}} }\limits_{(\operatorname{Re} d\;colour)} \; + \;3NaCl\]
Diazo compound $(—N=N—)$ do not give test of nitrogen as above, but a mixture of potassium carbonate and magnesium powder is used in place of sodium for the preparation of extract.
