Writeshortnotes on (i) Mustard oil reactions (ii) Carbylaminereaction (iii) Gabrielpathalimidesynthe$is

Writeshortnotes on (i) Mustard oil reactions (ii) Carbylaminereactio

1.	Writeshortnotes on (i) Mustard oil reactions (ii) Carbylaminereaction (iii) Gabrielpathalimidesynthe$is
Answer» Solution :Mustard oil reaction :(a) When primary amines aretretedwith carbon disulphide` (CS_(2))` , N - alkyldithiocarbonic acid is formedwhichon subsequent treatment with ` HgCI_(2)` givesan alkyl isothiocyanate . ` (##SUR_CHE_XII_V02_QP_E01_040_S01.png" width="80%"> (b)whenaniline is treatedwith carbondisuphide , or heatedtogether , S-diphenylthio urea is formed, whichon boiling with strongHCI, Phenyl isothiocyanate (phenyl mustedoil) , is formed Thesereactions are knowsas Hofmann-Mustard oil reaction.This testis usedto identifythe primaryamines. (ii) Carbylaminereaction : Aliphatic (or) aromaticprimaryaminesreact WITHCHLOROFORM and alcpholicKOH to giveisocyanides(carbylamins) , whichhas an unpleasantsmell. This reactionis known as carbylamines TEST. This testused to identifythe primaryamines ` underset(" Ethylamine")(C_(2)H_(5) - NH_(2)) + underset("Chloroform")( CHCI_(3) + 3KOH) to underset(" Ethylisocyanide")(C_(2)H_(5)- NC + 3KCI + 3H_(2)O)` (iii) Garbriel phthalimidesynthesis : Gabriel synthesis is used for thepreparation of Aliphaticprimaryamines. Phthalimide on treatment with ethanolicKOHforms potassiumsalt of Phthalimidewhichonheatingwith alkylhalidefollowedbyalkaline hydrolysis givesprimary AMINE. Aniline cannotbe preparedby thismethodbecausethe arylhalides do notundergo nucleophilicsubstitution with the anionformedby phthalimide.