Question

The IUPAC name(s) of the following compound is(are) Cc1ccc(Cl)cc1 [A] 1-chloro-4-methylbenzene [B] 4-chlorotoluene [C] 4-methylchlorobenzene [D] 1-methy1-4-chlorobenzene

Short answer

The IUPAC name of the compound is [A] 1-chloro-4-methylbenzene.

Step-by-step solution

Identify Structure

The SMILES notation provided represents a benzene ring with a chlorine (Cl) atom and a methyl group (CH3, abbreviated as C in SMILES) attached to it at different positions.

Determine Position of Substituents

In the SMILES string, the 'c1ccc(Cl)cc1' part denotes a benzene ring with chlorine at the first position (when numbering starts from Cl) and methyl group at the fourth position.

Apply IUPAC Naming Rules

According to IUPAC nomenclature rules, the substituents are listed in alphabetical order. Therefore, the chlorine (Cl) takes precedence over methyl (CH3), and numbering starts from the chlorine, making it '1-chloro'. The methyl group is at the fourth position, hence '4-methyl'.

Combine the Substituents with the Base Name

The base name for a benzene ring is 'benzene'. Combine the substituents with the base name to form the full IUPAC name, which is '1-chloro-4-methylbenzene'.

Key concepts

Organic Chemistry

Organic chemistry is a branch of chemistry that focuses on the study of carbon-containing compounds. This encompasses a vast array of substances that form the basis for life on Earth, as well as synthetic materials and polymers. Carbon's unique ability to form stable bonds with other carbon atoms, as well as with elements like hydrogen, oxygen, nitrogen, and halogens, leads to an extraordinary variety of chemical structures.

In organic chemistry, understanding the structures of organic molecules is crucial. This encompasses not only their chemical composition but also the shape, which can influence reactivity and properties. The vast diversity of organic compounds is categorized by functional groups, which are specific groupings of atoms within molecules that have characteristic properties and reactivity patterns.

SMILES Notation

The Simplified Molecular Input Line Entry System (SMILES) is a notation system that allows chemists to represent a chemical structure in a linear text format. This powerful tool is used for entering and conveying molecular information in databases and digital communication. For example, the SMILES string Cc1ccc(Cl)cc1 expertly defines the structure of a chlorinated methylbenzene molecule.

The beauty of SMILES notation lies in its simplicity and compactness. It includes atoms, represented by their element symbols, and bonds, depicted as lines or implied by adjacency, among other things. Parentheses are used to indicate branching, numbers to denote ring closures, and certain characters to represent double or triple bonds. Learning to read SMILES strings is an essential skill in modern chemistry, providing a way to quickly communicate complex molecular structures.

Chemical Compounds Naming

Naming chemical compounds is a central part of studying chemistry and involves a standardized system known as IUPAC (International Union of Pure and Applied Chemistry) nomenclature. This system allows chemists from around the world to communicate unambiguously about chemical compounds.

The rules for naming organic compounds take into account factors such as the length of the carbon chain, the types and numbers of functional groups present, and the position of those groups on the base carbon chain or ring structure. For the compound in the exercise, Cc1ccc(Cl)cc1, we carefully apply these rules. Identifying functional groups, determining their positions, and naming them in alphabetical order creates a clear, systematic name, in this case, '1-chloro-4-methylbenzene'.

Benzene Derivatives

Benzene derivatives are a fascinating group of organic compounds that consist of a benzene ring as the core structure, with one or more substituent groups attached. These compounds are fundamental in organic chemistry and have vast industrial and pharmacological applications.

The reactivity of benzene derivatives is heavily influenced by the substituents attached to the ring. Electron-donating groups can activate the ring, making it more reactive, while electron-withdrawing groups can have the opposite effect. The positioning of these substituents can dictate the reactivity towards electrophilic substitution reactions, which is a cornerstone of aromatic chemistry. For instance, the molecule named in the exercise is a derivative of benzene with chlorine and methyl substituents, and is commonly known as 1-chloro-4-methylbenzene or 4-chlorotoluene.