Case: Read the passage and answer the following questions
Aldehydes and ketones are generally prepared by oxidation of primary and secondary alcohols. Dehydrogenation of alcohols gives aldehydes and ketones. Ozonolysis alkenes give aldehydes ketones or a mixture of both depending on the substitution pattern of the alkene. Aldehydes are prepared from acyl chloride, nitrile, esters and even from hydrocarbons by different kinds of oxidation. Ketones are prepared from benzene or its derivatives through Friedel-Crafts acylation reaction. Carboxylic acids are prepared from aldehydes and ketones on oxidation. Nitriles are hydrolysed to amides and then to carboxylic acids. It is even prepared using Grignard’s reagent.
What is the product of hydrolysis of ozonide of 1-butene?
Answer & explanation
Correct answer: option 4
The correct answer is option 4. Methanal and propanal.
Ozonolysis of alkenes involves the cleavage of the double bond to form carbonyl compounds like aldehydes and ketones. The products depend entirely on the substitution pattern of the starting alkene.
- Identify the Structure: 1-butene has the chemical structure $CH_2=CH-CH_2-CH_3$.
- The Ozonolysis Process: When ozone reacts with 1-butene, it forms an ozonide intermediate.
- Hydrolysis (Cleavage): During reductive hydrolysis (usually with $Zn/H_2O$), the double bond is "split" in half, and an oxygen atom is attached to each of the carbon atoms that were part of the double bond.
- The left fragment ($CH_2=$) becomes Methanal ($HCHO$).
- The right fragment ($=CH-CH_2-CH_3$) becomes Propanal ($CH_3-CH_2-CHO$).
Summary of Reaction
This specific substitution pattern yields a mixture of two different aldehydes because 1-butene is an unsymmetrical alkene.