The volume of 1 M aqueous H2SO4 required to completely neutralize the ammonia evolved from 5.72 g of L in Kjeldahl's method of nitrogen estimation is mL.
Answer
10
Solution
[figure] [anhyd. AlCl3]ClCOCH2Cl [figure]
Friedel–Crafts acylation at C-4 (ortho to one CH3, para to the other; both groups activate this position).
[figure] [heat]NaI [figure]
Finkelstein reaction: Cl is replaced by I.
[figure] sodium 3-nitrophenoxide [figure] (J)
Williamson synthesis: the phenoxide ion displaces I- (SN2).
[figure] NaBH4 [figure]
NaBH4 reduces the ketone to a 2° alcohol (the -NO2 group is not touched).
[figure] PBr3 [figure] (K)
OH is replaced by Br: K = C16H16BrNO3 =350 g mol-1 (matches the given value).
[figure] NH3 (excess) [figure] (L)
Ammonolysis: Br is replaced by -NH2; L = C16H18N2O3, molar mass 350-80+16=286 g mol-1.
Moles of L = 5.72286=0.02
In Kjeldahl's method the nitro N is not converted into ammonia; only the amino N gives NH3: 0.02 mol NH3.
2NH3+H2SO4 (NH4)2SO4: H2SO4=0.01 mol =10 mL of 1 M solution
Answer: 10