(A) Write the chemical equation for the reaction involved in Cannizzaro reaction. (b) Draw the structure of the semicarbazone of ethanal. (c ) Why pK_(a)of F- CH_(2) - COOH is lower than that of Cl - CH_(2) -COOH ? (d) Write the product in the following reaction : CH_(3) -CH= CH- CH_(2) CN underset((ii) H_(2)O)overset((i)DIBAL-H)(rarr)(e ) How can you distinguish between propanal and propanone ?

(A) Write the chemical equation for the reaction involved in Cannizzar

1.	(A) Write the chemical equation for the reaction involved in Cannizzaro reaction. (b) Draw the structure of the semicarbazone of ethanal. (c ) Why pK_(a)of F- CH_(2) - COOH is lower than that of Cl - CH_(2) -COOH ? (d) Write the product in the following reaction : CH_(3) -CH= CH- CH_(2) CN underset((ii) H_(2)O)overset((i)DIBAL-H)(rarr)(e ) How can you distinguish between propanal and propanone ?
Answer» Solution :(a) Cannizzaro.s reaction `HCHO+HCHO UNDERSET(NaOH)overset("Conc.")(rarr)underset("Sodium formate")(HCOONa)+underset("Methyl alcohol")(CH_(3)OH)` (b) `underset("Semi carbazone of ethanal")(CH_(3)CH = N N HCONH_(2))` (c ) Fluorine has a stronger -I inductive effect than chlorine. Therefore, fluoroacetic acid is stronger than chloroacetic acid. Greater the acid strength, smaller is the `pK_(a)` value `pK_(a)= - log K_(a)` Therefore, `F - CH_(2) COOH` hasa lower `pK_(a)` value than `CL - CH_(2) COOH` (d ) `CH_(3) - CH = CH - CH_(2) CN underset((ii) H_(2)O)overset( (i)DIBAL-H)(rarr) CH_(3) - CH = CH - CH_(2) CHO` ( e ) Propanal GIVES the Tollen.s reagent test while propanone does not. Silver mirror is formed on adding ammonical silver nitrate solution to propanal and heating.