Question

The correct IUPAC name of compound cyclobutyl cyclopropane is (A) Bicycloheptene (B) Cyclobutyl cyclobutene (C) Dicyclobutyl propane (D) Cyclopropyl cyclobutane

Short answer

The correct IUPAC name for the given compound "cyclobutyl cyclopropane" is (D) Cyclopropyl cyclobutane.

Step-by-step solution

Identify the main structural units of the compound

In "cyclobutyl cyclopropane", there are two cycloalkane rings: a cyclobutane ring (4 carbon atoms) and a cyclopropane ring (3 carbon atoms). The main structural units are cyclobutyl group and cyclopropane ring.

Determine the parent part of the compound

The parent part is the one that has the most carbon atoms. In our case, cyclobutane has more carbon atoms, meaning it will be the parent part of the compound.

Determine the substituent and numbering the parent ring

Since cyclobutane is the parent part, cyclopropane becomes the substituent and needs to be attached to the parent part in the most favorable position. The substituent will be named as cyclopropyl- and attached to the cyclobutane parent part.

Write the IUPAC name

Since the cyclopropane is attached to the cyclobutane, the IUPAC name becomes Cyclopropyl cyclobutane.

Identify the correct option

Based on the IUPAC name we determined, the correct answer is: (D) Cyclopropyl cyclobutane

Key concepts

Cycloalkanes

Cycloalkanes are a class of hydrocarbons that contain carbon atoms arranged in a ring or closed-loop structure. The general formula for cycloalkanes is \( C_nH_{2n} \), where \( n \) represents the number of carbon atoms in the ring.
Cycloalkanes are named by adding the prefix "cyclo-" to the alkane name that corresponds to the number of carbon atoms in the ring. For example:

• Cyclopropane has three carbon atoms.
• Cyclobutane has four carbon atoms.
• Cyclopentane has five carbon atoms, and so forth.

Cycloalkanes are quite stable but can have higher strain when fewer carbon atoms are involved, due to torsional strain and angle strain.

Structural Units

The primary structural units in a chemical compound refer to the basic framework from which the compound is constructed. In the context of IUPAC nomenclature for cycloalkanes, determining the main structural unit is crucial.
This involves identifying which cycloalkane ring has the most carbon atoms, as it generally becomes the parent compound. For instance, in the compound 'cyclobutyl cyclopropane', the structural units include:

• Cyclobutane ring, which forms the parent structure.
• Cyclopropane ring, which acts as a substituent.

By determining these units, one can correctly name and understand the properties and reactivities of the compound.

Cyclobutane

Cyclobutane is a cycloalkane with four carbon atoms forming a square ring, represented by the chemical formula \( C_4H_8 \). It is less strained compared to cyclopropane due to a closer approach to ideal bond angles.
When naming compounds that include a cyclobutane ring, it often serves as the parent structure due to having more carbon atoms, as seen in the case of 'cyclopropyl cyclobutane'.
Understanding its role as a parent structure is essential in IUPAC nomenclature because it determines the main framework around which other substituents are named and connected.

Cyclopropane

Cyclopropane is the simplest cycloalkane, consisting of a three-carbon ring with the formula \( C_3H_6 \). It is known for its significant angle strain due to the sharp \( 60^\circ \) bond angles, which deviate from the tetrahedral angle of \( 109.5^\circ \).
This strain makes cyclopropane more reactive compared to other larger cycloalkanes like cyclobutane.
In compound naming, cyclopropane often acts as a substituent when attached to a larger ring, named as 'cyclopropyl'. This is evident in the naming of 'cyclopropyl cyclobutane', where cyclopropane attaches to the cyclobutane parent.