Question

Write the structures of the following organic halogen compounds. (i) 2-Chloro-3-methylpentane (ii) \(p\) -Bromochlorobenzene (iii) 1-Chloro-4-ethylcyclohexane (iv) 2-(2-Chlorophenyl)-1-iodooctane (v) 2-Bromobutane (vi) 4 -tert-Butyl-3-iodoheptane (vii) 1-Bromo-4-sec-butyl-2-methylbenzene (viii) 1.4-Dibromobut-2-ene 0

Short answer

Draw each compound based on the given IUPAC names by identifying the parent chain, functional groups, and substituents' positions.

Step-by-step solution

Understand the Basic Nomenclature Rules

To solve the problem, start with understanding IUPAC nomenclature for organic compounds. Organic halides are named based on the longest carbon chain, substituents, and numbering to minimize substituent numbers.

Structure of 2-Chloro-3-methylpentane

The base chain is 'pentane' (5 carbon atoms long). Number from the end closest to the first substituent: 1. The chlorine (Cl) is attached to the second carbon. 2. A methyl group (CH₃) is attached to the third carbon. The structure is: CH₃-CH(Cl)-CH(CH₃)-CH₂-CH₃.

Structure of p-Bromochlorobenzene

The term 'para' (p) means the substituents are on opposite ends of the benzene ring (positions 1 and 4). Place chlorine (Cl) on one carbon and bromine (Br) on the opposite side of a benzene ring.

Structure of 1-Chloro-4-ethylcyclohexane

Cyclohexane acts as the base ring. 1. Attach chlorine (Cl) to carbon 1. 2. Attach an ethyl group (CH₂CH₃) to the fourth carbon, counting from the chlorine attachment.

Structure of 2-(2-Chlorophenyl)-1-iodooctane

The main chain is "octane" (8 carbon length). 1. Place iodine (I) on carbon 1. 2. Attach a phenyl group (a benzene ring) with a chlorine on its second carbon at the octane’s second carbon.

Structure of 2-Bromobutane

The base chain is 'butane.' 1. Attach a bromine atom (Br) to the second carbon, resulting in: CH₃-CH(Br)-CH₂-CH₃.

Structure of 4-tert-Butyl-3-iodoheptane

The base chain is 'heptane' (7 carbon atoms). 1. Attach iodine (I) to carbon 3. 2. Attach a tertiary butyl group (a central carbon attached to three CH₃) to carbon 4.

Structure of 1-Bromo-4-sec-butyl-2-methylbenzene

The benzene ring has: 1. Bromine (Br) on carbon 1. 2. Sec-butyl (a butyl chain branching from its second carbon) on carbon 4. 3. Methyl (CH₃) on carbon 2.

Structure of 1,4-Dibromobut-2-ene

The compound has a butene skeleton with a double bond starting at carbon 2. 1. Bromine atoms (Br) attached to carbons 1 and 4. The structure can be shown as: Br-CH₂-CH=CH-CH₂-Br.

Key concepts

IUPAC Nomenclature

Understanding the IUPAC nomenclature system is essential for naming and drawing the structures for organic halogen compounds. This internationally agreed method ensures consistency and clarity in naming organic molecules. The names of compounds follow a logical order based on several rules such as:

• Select the longest continuous carbon chain as the parent structure and name it using the appropriate alkane series name.
• Identify and name all substituents connected to the main carbon chain. These could be halogens like bromine (Br), chlorine (Cl), as well as other groups such as methyl (CH₃) and ethyl (C₂H₅).
• Assign a location number to each substituent, choosing the numbering that provides the smallest set of numbers.
• Order substituents alphabetically in the name, regardless of their position number on the chain.

Following these steps ensures that the chemical name precisely describes the compound's structure. For example, in '2-Chloro-3-methylpentane', the longest chain has 5 carbon atoms (pentane), with chlorine on the second carbon and a methyl group on the third carbon.

Organic Chemistry

Organic chemistry focuses on understanding the structure, properties, and reactions of carbon-based compounds which can range from simple molecules to complex ones with multiple elements, including hydrogen, oxygen, nitrogen, and halogens.
These compounds, known as organic halogen compounds, are part of this vast field due to the presence of halogen atoms (such as fluorine, chlorine, bromine, and iodine) bonded to carbon.
Halogens add unique characteristics to organic molecules:

• They increase the reactivity of molecules, often making them reactive centers in chemical reactions.
• Organic halides serve as intermediates in many chemical syntheses, given their adaptable structures.
• They also influence the physical properties, like boiling and melting points, due to their electronegative nature.

Learning these basics will help you grasp why organic halogens are crucial in fields ranging from synthetic chemistry to pharmaceuticals.

Structural Formulas

Structural formulas provide a detailed depiction of the arrangement of atoms within a molecule, showing not just the number of each atom, but also illustrating their connections.
For organic halogen compounds, structural formulas highlight the carbon backbone and exactly where halogens like chlorine, bromine, and iodine attach.
Consider the structure of '1-Chloro-4-ethylcyclohexane':

• A cyclohexane ring serves as the base structure.
• Chlorine is attached to the first carbon of the ring.
• An ethyl group attaches at the fourth carbon, creating a specific spatial arrangement.

Structural formulas can be written in condensed form, like CH₃-CH(Cl)-CH(CH₃)-CH₂-CH₃ for '2-Chloro-3-methylpentane', or with detailed line drawings displaying every bond and angle. They play a key role in visualizing molecules and predicting how they might interact or react with other substances.

Organic Halides

Organic halides, also known as haloalkanes, consist of carbon chains with one or more halogen atoms. These compounds are significant in practical applications ranging from industrial solvents to pharmaceuticals.
The diversity of organic halides is vast thanks to the variety of possible carbon chain lengths, branching patterns, and halogen types.
Key characteristics include:

• They can undergo reactions such as nucleophilic substitution and elimination, fundamental to creating new and useful compounds.
• The presence of halogens, due to their electronegativity, can influence molecule polarity, significantly affecting physical and chemical properties.
• Common examples include household cleaning agents and certain anesthetics.

Recognizing the presence and position of halogens on carbon structures is crucial for understanding both the molecule's naming and functionality.