Question

Ozonolysis of 2,3 -dimethyl-1-butene followed by reduction with zinc and watcr gives (1) methanoic acid and 3 -methyl-2-butanone (2) methanal and 2 -methyl-2-butanone (3) methanal and 3-methyl-2-butanone (4) methanoic acid and 2 -methyl-2-butanone

Short answer

Option (3): methanal and 3-methyl-2-butanone.

Step-by-step solution

- Identify the Alkene Structure

The given compound is 2,3-dimethyl-1-butene. This means the structure is: CH2=C(CH3)-CH2-CH3

- Apply Ozonolysis

During ozonolysis, the double bond in the alkene is cleaved, and the carbon atoms involved in the double bond each gain an oxygen atom. Thus, the structure will split into two parts: CH2=O and CH3-C(O)(CH3)-CH3

- Assign Structures Post Ozonolysis

The two resulting fragments are methanal (formaldehyde) and 3-methyl-2-butanone. These are the cleaved products post the ozonolysis step.

- Compare with the Given Options

Now, compare the formed products with given options: (1) methanoic acid and 3-methyl-2-butanone (2) methanal and 2-methyl-2-butanone (3) methanal and 3-methyl-2-butanone (4) methanoic acid and 2-methyl-2-butanone The products from ozonolysis match option (3).

Key concepts

alkenes

Alkenes are a class of hydrocarbons that contain at least one carbon-carbon double bond (C=C). This double bond is their defining feature and contributes to their chemical reactivity. Alkenes follow the general formula CnH2n, which means that for every n carbon atoms, there are 2n hydrogen atoms. One of the simplest alkenes is ethene (C2H4), commonly known as ethylene.
The double bond in alkenes can be involved in various chemical reactions, including addition, polymerization, and oxidation. These reactions often break the double bond and form new products, making alkenes highly versatile in organic synthesis.

• The presence of the double bond makes alkenes more reactive than alkanes, which only have single bonds.
• Alkenes can be found in many natural sources and are important in both industry and biological processes.
• The position and the substituents (groups attached) around the double bond can significantly affect the properties and reactivity of alkenes.

organic reaction mechanisms

Organic reaction mechanisms describe the step-by-step process by which organic molecules undergo chemical reactions. Understanding these mechanisms is crucial for predicting the outcomes of reactions and for designing new synthetic pathways. One of the keys to mastering organic mechanisms is recognizing the role of intermediates, transition states, and the movement of electrons.
In reactions involving alkenes, the double bond typically serves as a site of reactivity. For instance, in ozonolysis, the double bond of an alkene is attacked by ozone (O3), leading to the breaking of the double bond and the formation of ozonides. These ozonides are then typically reduced to yield carbonyl compounds.

• Common organic reaction mechanisms include substitution, addition, elimination, and rearrangement reactions.
• Mechanistic steps often involve intermediates such as carbocations, carbanions, or free radicals.
• The study of reaction mechanisms helps chemists manipulate molecules to create desired products efficiently and safely.

ozonolysis products

Ozonolysis is an organic reaction where ozone (O3) is used to cleave the double bond of an alkene, resulting in the formation of carbonyl compounds. The products can either be aldehydes, ketones, or carboxylic acids, depending on the structure of the starting alkene and the conditions of the reaction.
For instance, in the given exercise, ozonolysis of 2,3-dimethyl-1-butene followed by reduction with zinc and water results in the formation of methanal (formaldehyde) and 3-methyl-2-butanone. Here's a step-by-step on how this happens:

• The double bond in 2,3-dimethyl-1-butene is cleaved.
• Each carbon involved in the original double bond gains an oxygen, forming intermediate ozonides.
• These ozonides are then reduced to form methanal and 3-methyl-2-butanone.

This reaction helps us understand that the position of the substituents around the double bond will influence the structure of the resultant carbonyl compounds. Thus, ozonolysis is a powerful tool in organic chemistry for breaking down complex molecules into simpler, identifiable parts.