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Structural Formula Part-2

Structural Formula

source : source forge.net

Structural Formula

Q 1-Molecular formula of compd is C2H5NO. Compd when heated with Br2 & alc. KOH gives colourless gas of ammonical odour. Gas reacts with HCl to form white fumes . This gas on reaction with HNO2 gives alcohol & N2. Give formula of the comd &explain the reactions ?

Solution-

C2H5NO is an amide which is CH3CONH2

CH3CONH2 +Br2 + 4KOH(alc.)——>CH3NH2 + 2KBr +K2CO3 +2H2O

Methyl amine is  colourless gas of ammonical odour , it gives  white fumes with HCl.

CH3NH2 + HCl —–>CH3NH2.HCl(white fumes)

Methyl amine

CH3NH2 reacts with HNO2 gives alcohol & N2.

CH3NH2 + HNO2———>CH3OH +N2 +H2O

( alcohol )

So , compd is CH3CONH2 ( acetamide).


Q 2– Compd ‘A’  C3H6O2 on hydrolysis gives acid  ‘B’ & alcohol ‘C’. Acid ‘B’ on heating with soda lime gives CH4.Give name & formula of  ‘A’, ‘B’ &’C’ .

Ans. Compd ‘A’  C3H6O2  is an ester because ester on hydrolysis gives acid & alcohol. Hence ‘A’ is CH3COOCH3 (methyl acetate or methyl ethanoate).

soda lime is a mixture of NaOH & CaO.

 

Hence ‘A’ is CH3COOCH3 (methyl acetate or methyl ethanoate) ;’B’ is  CH3COOH (acetic acid or ethanoic acid) ; ‘C’ is CH3OH (methyl alcohol or methanol).


Q 3–  Molecular formula of neutral compound ‘A’ is C3H6O2. ‘A’ on hydrolysis gives monobasic acid ‘B’& a neutral compd ‘C’. Compd ‘C’ gives iodoform test . Give  formula & name of  ‘A’, ‘B’ & ‘C’.

Solution-

‘A’ is a neutral compd , on hydrolysis gives monobasic acid ‘B’& a neutral compd ‘C’.Therefore ‘A’ is an ester.

‘C’ gives iodoform test, hence it is C2H5OH & monobasic acid is HCOOH.

Hence ester is HCOOC2H5 (ethyl formate or ethyl methanoate).

HCOOC2H5 + H2O —->HCOOH + C2H5OH

A                                          B                    C

(ethyl methanoate)       ( formic acid) (ethyl alcohol)

C2H5OH +I2 + NaOH ——> CHI3 + HCOONa +NaI +H2O

iodoform

‘A’ is  HCOOC2H5 (ethyl formate or ethyl methanoate) ; ‘B’ is HCOOH (formic acid or methanoic acid) ;’C’ is C2H5OH (ethyl alcohol or ethanol).


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Saroj Bhatia: Dr. Saroj Bhatia is an Ph.D in chemistry who has been teaching chemistry for over a decade. Currently she is a respected principal of a renowned college in her hometown. She took this medium for online users. Her proudest achievement is helping people learn chemistry.
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