Question

Match the elements of Column I to elements of Column II. There can be single or multiple matches. Column I (a) Neopentane (b) Cyclohexane (c) 2,2 -dimethyl butane (d) \(2,2,3,3-\) tetramethyl butane Column II (p) equatorial hydrogens (q) Secondary hydrogens (r) Quaternary carbon (s) Only one monochloro derivative

Short answer

Question: Match the compounds in Column I with the features in Column II: Column I (a) Neopentane (b) Cyclohexane (c) 2,2-dimethyl butane (d) 2,2,3,3-tetramethyl butane Column II (p) equatorial hydrogens (q) Secondary hydrogens (r) Quaternary carbon (s) Only one monochloro derivative Answer: (a) Neopentane - (r) Quaternary carbon & (s) Only one monochloro derivative (b) Cyclohexane - (p) equatorial hydrogens & (q) Secondary hydrogens (c) 2,2-dimethyl butane - (q) Secondary hydrogens (d) 2,2,3,3-tetramethyl butane - (r) Quaternary carbon

Step-by-step solution

Identify the compounds

Draw the structural formulas of the compounds in Column I as follows: (a) Neopentane (b) Cyclohexane (c) 2,2-dimethyl butane (d) 2,2,3,3-tetramethyl butane

Identify the features

Look for the features mentioned in Column II: (p) equatorial hydrogens (q) Secondary hydrogens (r) Quaternary carbon (s) Only one monochloro derivative

Analyze the matches

Now, let's proceed to match the elements from both the columns. (a) Neopentane Neopentane has a quaternary carbon and it forms only one monochloro derivative. Thus, it matches with (r) and (s). (b) Cyclohexane Cyclohexane has equatorial hydrogens in its chair conformation as well as secondary hydrogens. Thus, it matches with (p) and (q). (c) 2,2-dimethyl butane 2,2-dimethyl butane also has secondary hydrogens. Thus, it matches (q). (d) \(2,2,3,3-\) tetramethyl butane 2,2,3,3-tetramethyl butane has quaternary carbon. Thus, it matches (r). So, the matches are as follows: Column I - Column II (a) Neopentane - (r) Quaternary carbon & (s) Only one monochloro derivative (b) Cyclohexane - (p) equatorial hydrogens & (q) Secondary hydrogens (c) 2,2-dimethyl butane - (q) Secondary hydrogens (d) \(2,2,3,3-\) tetramethyl butane - (r) Quaternary carbon

Key concepts

Structural isomers

Structural isomers are molecules that share the same molecular formula but have different structural arrangements. This means that while they contain the same number of atoms of each element, the way these atoms are connected differs. Such differences can lead to significant variations in their chemical and physical properties.

In the original exercise, compounds like neopentane and 2,2-dimethyl butane are examples of structural isomers. Both have the formula \( C_5H_{12} \) but differ in the arrangement of their carbon atoms. This rearrangement affects factors such as boiling points, density, and reactivity. If you can picture reconfiguring a Lego set to build different shapes using the same pieces, you understand the basics of structural isomerism.

• These isomers are crucial in organic chemistry as they help in designing chemicals with specific desired properties.
• Understanding structural isomers aids in grasping concepts such as functional groups and stereochemistry.

Hydrogen classification

In organic chemistry, classifying hydrogens helps in understanding reactivity patterns and mechanisms of compounds. Hydrogens can be classified as primary (attached to a primary carbon), secondary (attached to a secondary carbon), or tertiary (attached to a tertiary carbon). Each type reflects the degree of substitution of the carbon atom it's attached to.

For instance, the original exercise identifies secondary hydrogens in cyclohexane and 2,2-dimethyl butane. Secondary hydrogens are bonded to carbons that are directly connected to two other carbon atoms. This classification is vital as it indicates the potential reactions these hydrogens might undergo, such as in substitution or elimination reactions.

• This classification plays a critical role in predicting the stability and formation of radicals.
• The type of hydrogen often dictates the compound's behavior in chlorination and other substitution reactions.

Chlorination reactions

Chlorination reactions involve the substitution of hydrogen atoms in a hydrocarbon with chlorine atoms, typically through a chain reaction mechanism that includes initiation, propagation, and termination steps. This process is known as free radical chlorination, where the introduction of chlorine atoms can significantly change the nature of the original compound.

In the original exercise, neopentane is noted for having only one monochloro derivative. This implies that when neopentane undergoes chlorination, only one type of chlorinated product is formed, due to its symmetrical structure and uniform environment of hydrogen atoms. The concept of symmetry is key here because it limits the number of distinct products.

• Knowing how many monochloro derivatives can be formed helps in understanding the selectivity of reactions.
• Chlorination and similar halogen substitution reactions are fundamental in synthesizing a wide range of useful chemical products.

Quaternary carbon

A quaternary carbon is a carbon atom bonded to four other carbon atoms and does not bear any hydrogen atoms. This type of carbon is important because it introduces steric hindrance, affecting the compound's reactivity and interactions with other molecules.

In the given exercise, both neopentane and 2,2,3,3-tetramethyl butane are noted for having a quaternary carbon, which is a significant structural feature. A quaternary carbon creates a crowded environment, making certain reactions less feasible, especially those requiring open access to the carbon center.

• Compounds containing quaternary carbons are often staples in studying branch points in organic synthesis.
• The presence of such carbon can influence not only physical properties but also the types of reactions in which a molecule can participate.