1.

(a) What is iodoform test? (b) Discuss the main chemical properties of C CI_(4)

Answer»

Solution :(a) Compounds containing `CH_(3) CH(OH)` or `CH_(3)-overset(O)overset(||)C-` structural units, when heated with iodine and an aquoeus solution of sodium carbonate or sodium HYDROXIDE, give yellow precipitate of iodoform. Therefore this reaction is of diagnostic value and is used in qualitative analysis to detect these structural units under the name iodoform test.
i.e `2NaOH+I_(2) to UNDERSET("Sod. hypoiadite")(NaOI+NaI+ H_(2)O)`
`R- overset(OH)overset(|)CH-CH_(3)+NaOI overset("Oxidation")to R-overset(O)overset(||)C-CH_(3)+NaI+H_(2)O`
`R-overset(O)overset(||)C-CH_(3)+3NaOI overset("lodination")to R-overset(O)overset(||)C-Cl_(3)+3NaOH`
`R-overset(O)overset(||)C-Cl_(3)+NAOH overset("Hydrolysis")to CHI_(3)+R-overset(O)overset(||)C-ONa`
(b) Some chemical properties of `C CI_(4)` are :
(i) Reduction :`C Cl_(4)+ 2[H] overset(Fe//H_(2)O)CHCl_(3)+HCl`
(ii) Hydrolysis : `C Cl_(4)+4KOH to underset("Unstable")([C(OH)_(4)]) to CO_(2)+ 2H_(2)O`
`CO_(2)+2KOH to K_(2)CO_(3)+ H_(2)O`


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