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An alkene ‘A’ (Mol. formula C 5 H 10 ) on ozonolysis gives a mixture of two compounds ‘B’ and ‘C’. Compound ‘B’ gives positive Fehling’s test and also forms iodoform on treatment with I 2 and NaOH. Compound ‘C’ does not give Fehling’s test but forms iodoform. Identify the compounds A, B and C. Write the reaction for ozonolysis and formation of iodoform from B and C. 

Answer

A is an Alkene with the chemical formula: C 5 H 10

Its structure can be drawn as any of the following:

ISOMERS OF C5H10  - Teachoo.jpg

Compound A is an alkene, so, on ozonolysis it will give carbonyl compounds B and C.

We know that, 

  • B gives positive Fehling’s test : so it is an aldehyde .

It gives positive Iodoform tes t so it has CH3C=O group . This means the aldehyde is acetaldehyde .

FEHLING'S TEST FOR ALDEHYDES - Teachoo.jpg

IODOFORM TEST FOR ACETALDEHYDES AND METHYL KETONES - Teachoo.jpg

Also, 

  • C does not give Fehling’s test : it is a ketone
  • It gives positive iodoform test so it is a methyl ketone.  

IODOFORM TEST FOR ACETALDEHYDES AND METHYL KETONES - Teachoo.jpg

  • A methyl ketone must have at least three carbon atoms .

ISOMERS OF C5H10  - Teachoo.jpg

Based on ozonolysis mechanism, 

Only A= satisfies this condition.

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.