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)
1.5 Detection of Halogens
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
Lassaigne test: The extract is boiled with. $HN{O_3}$ to expel nitrogen and sulphur, because $NaCN$ and $N{a_2}S$ react with $AgN{O_3}$ to give white and black precipitates, respectively. \[NaCN\; + \;AgN{O_3}\xrightarrow{{}}\;AgCN \downarrow \; + \;NaN{O_3}\]\[N{a_2}S\; + \;2AgN{O_3}\xrightarrow{{}}\;A{g_2}S \downarrow \; + \;2NaN{O_3}\]
Boiling with conc.$HN{O_3}$ evolves $HCN$ and ${H_2}S$ as volatile gases.\[NaCN\; + \;\mathop {HN{O_3}}\limits_{(Conc.)} \;\xrightarrow{\Delta }\;NaN{O_3} + HCN \uparrow \]\[N{a_2}S\; + \;\mathop {2HN{O_3}}\limits_{(Conc.)} \xrightarrow{\Delta }\;2NaN{O_3} + {H_2}S \uparrow \]
Now add $AgN{O_3}$ solution.
(i) Formation of a curdy white precipitate which is soluble in $N{H_4}OH$ solution shows the presence of chlorine.\[NaCl\; + \;AgN{O_3}\xrightarrow{{}}\mathop {AgCl}\limits_{(White)} \downarrow \; + \;NaN{O_3}\]
(ii) Formation of a light yellow ppt, which is sparingly soluble in $N{H_4}OH$ shows the presence of iodine.\[NaI\; + \;AgN{O_3}\xrightarrow{{}}\mathop {AgBr}\limits_{(Light\;yellow)} \downarrow \; + \;NaN{O_3}\]
(iii) Formation of a lemon yellow ppt. insoluble in $N{H_4}OH$ shows the presence of iodine.\[NaI + \;AgN{O_3}\;\xrightarrow{{}}\;\mathop {AgI \downarrow }\limits_{(Lemon\;yellow)} \; + \;NaN{O_3}\]
