Discuss the chemistry of Lassaigne's test.

Solution

Nitrogen, sulphur, halogens and phosphorus present in an organic compound are detected by 'Lassaigne's test'. The elements present in the compound are converted from the covalent form into the ionic form by fusing the compound with sodium metal.
Reactions involved during fusion.
$bold space bold space bold space bold space bold Na bold space bold plus bold space stack bold C bold space bold plus bold space bold N with bold left parenthesis bold From bold space bold Organic bold space bold compound bold right parenthesis below bold space bold space bold rightwards arrow with bold Fusion on top bold space bold space bold NaCN with bold Sodium bold space bold cyanide below space bold 2 bold Na bold space bold plus bold space bold S with bold left parenthesis bold Form bold space bold organic bold space bold compound bold right parenthesis below bold space bold space bold rightwards arrow with bold Fusion on top bold space bold space bold space bold space stack bold Na subscript bold 2 bold S with bold Sodium bold space bold sulphide below bold space bold space bold space bold space bold Na bold space bold plus bold space stack bold X with bold underbrace below with bold From bold space bold organic bold space bold compound below bold space bold space bold space bold rightwards arrow with bold Fusion on top bold space bold NaX with stack bold Sodium bold space bold halide with bold left parenthesis bold X bold space bold equals bold space bold Cl bold comma bold space bold Br bold comma bold space bold I bold right parenthesis below below$
Cyanide, sulphide and halide of sodium so formed in sodium fusion are extracted from the fused mass by boiling it with distilled water. This extract is known as sodium fusion extract.

Some More Questions From Organic Chemistry – Some Basic Principles and Techniques Chapter

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Organic Chemistry – Some Basic Principles And Techniques

Discuss the chemistry of Lassaigne's test.

Some More Questions From Organic Chemistry – Some Basic Principles and Techniques Chapter

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