Question

Which mixture cannot be separated by using \(9-\mathrm{BBN} ?\) (A) Ethane and Ethene (B) 1-pentene and 2-pentene (C) Propene and l-butene (D) Ethene and 2-butene

Short answer

The question is not well-posed as all of the given mixtures (Ethane and Ethene; 1-pentene and 2-pentene; Propene and 1-butene; Ethene and 2-butene) contain only alkenes, and since 9-BBN doesn't react with alkenes, it cannot separate any of them.

Step-by-step solution

Analyze mixture A (Ethane and Ethene)

Mixture A contains ethane (an alkane) and ethene (an alkene). Since 9-BBN selectively reduces alkynes to alkenes and doesn't affect alkenes, this mixture cannot be separated using 9-BBN.

Analyze mixture B (1-pentene and 2-pentene)

Mixture B contains 1-pentene and 2-pentene, both of which are alkenes. Since 9-BBN doesn't react with alkenes, it cannot separate this mixture.

Analyze mixture C (Propene and 1-butene)

Mixture C contains propene and 1-butene, both of which are also alkenes. Similar to the previous mixtures, 9-BBN cannot separate this mixture as it doesn't affect alkenes.

Analyze mixture D (Ethene and 2-butene)

Mixture D contains ethene (an alkene) and 2-butene (also an alkene). This mixture cannot be separated using 9-BBN since it doesn't affect alkenes. All mixtures contain only alkenes, and since 9-BBN doesn't react with alkenes, it cannot separate any of the given mixtures. Thus, the question is not well-posed as all of the given mixtures cannot be separated by using 9-BBN.

Key concepts

9-BBN

9-BBN, or 9-Borabicyclo[3.3.1]nonane, is a chemical reagent renowned for its selective properties. It plays a crucial role in organic chemistry, especially in the reaction of alkenes and alkynes. However, its most distinctive feature is its preference for reducing certain bonds without affecting others.

• 9-BBN is mainly used for the hydroboration-oxidation of alkynes to produce alkenes.
• It acts selectively and doesn't react with isolated alkenes, making it a perfect choice for specific synthetic pathways.
• This selectivity makes 9-BBN a go-to when aiming to manipulate a mixture containing reactive components without disturbing stable alkenes.

By allowing chemists to reduce alkynes specifically, 9-BBN simplifies complex reactions while maintaining stability in other molecular areas.

Alkenes

Alkenes are unsaturated hydrocarbons containing at least one carbon-to-carbon double bond. They are highly important in both industrial applications and organic synthesis.

• The double bond in alkenes makes them more reactive compared to their alkane counterparts.
• They can participate in various reactions, such as hydrogenation, to become alkanes or polymerize to form materials like polyethylene.
• In mixtures, recognizing which components are alkenes is crucial, especially when using selective reagents like 9-BBN, which do not affect alkenes.

Understanding alkenes' structure and reactivity is essential for choosing the right conditions and reagents during chemical reactions.

Chemical Reactivity

Chemical reactivity refers to the rate and conditions under which a chemical substance undergoes a reaction. Different compounds display unique reactivity profiles based largely on their structure and the type of chemical bonds they contain.

• For example, alkenes are more reactive than alkanes due to their double bonds.
• The presence of these double bonds allows alkenes to undergo addition reactions, which are pivotal in synthetic chemistry.
• Selectivity in chemical reactions, like those involving 9-BBN, relies on exploiting differences in reactivity among different types of bonds.

By focusing on reactivity, chemists can strategically plan reactions to achieve desired products without unwanted side reactions.

Selective Reduction

Selective reduction is a critical concept in chemistry where a reagent selectively reduces certain bonds but leaves others unaffected. This precision is particularly significant when working with complex molecular structures.

• 9-BBN selectively reduces alkynes to alkenes, making it invaluable in differentiating between similar functional groups.
• In a mixture with alkenes, selective reduction is not feasible with 9-BBN due to its inactivity towards alkenes.
• Understanding and utilizing selective reduction allows chemists to manipulate molecular structures accurately and efficiently.

This concept underscores the importance of choosing the right reagents for specific reactions, minimizing unwanted side reactions, and achieving precise conversion in chemical processes.