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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 is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths and Science at Teachoo.