Question

Name or write the condensed structural formula for the following compounds: (a) trans-2-pentene (b) 2,5-dimethyl-4-octene (c) CCC=CCC(C)CC (d) Brc1ccc(Br)cc1 (c) C#CCC(C)(C)CC

Short answer

Short Answer: (a) trans-2-pentene: \(CH_3CH=CHCH_2CH_3\) (b) 2,5-dimethyl-4-octene: \(CH_3CH(CH_3)CH_2CH=CH(CH_3)CH_2CH_3\) (c) 4-methyl-3-hexene: \(CH_3CH_2CH=CHCH(CH_3)CH_2CH_3\) (d) 1,4-dibromobenzene: \(Br-C_6H_4-Br\) (e) 3-methyl-2-pentyne: \(CH_3C≡CCH(CH_3)CH_2CH_3\)

Step-by-step solution

(a) trans-2-pentene

To draw the condensed structural formula of trans-2-pentene, we need to interpret the IUPAC name and follow these steps: 1. Pentene indicates a 5-carbon chain with a double bond. 2. "2" indicates the double bond is between the second and third carbon atoms. 3. "trans" denotes that the two higher priority groups (in this case, the larger alkyl groups) are on opposite sides of the double bond. Thus, the condensed structural formula for trans-2-pentene is: CH3CH=CHCH2CH3

(b) 2,5-dimethyl-4-octene

To draw the condensed structural formula for 2,5-dimethyl-4-octene, we need to interpret the IUPAC name as follows: 1. Octene indicates an 8-carbon chain with a double bond. 2. "4" indicates the double bond is between the fourth and fifth carbon atoms. 3. "2,5-dimethyl" indicates methyl groups are attached to the second and fifth carbon atoms. So, the condensed structural formula for 2,5-dimethyl-4-octene is: CH3CH(CH3)CH2CH=CH(CH3)CH2CH3

(c)\CCC=CCC(C)CC\

To draw the condensed structural formula for this compound, we need to interpret the SMILES notation: CCC=CCC(C)CC has the IUPAC name: 4-methyl-3-hexene Next, we will draw the condensed structural formula for 4-methyl-3-hexene: CH3CH2CH=CHCH(CH3)CH2CH3

(d)\Brc1ccc(Br)cc1\

To draw the condensed structural formula for this compound, we need to interpret the SMILES notation: Brc1ccc(Br)cc1 has the IUPAC name: 1,4-dibromobenzene The condensed structural formula for 1,4-dibromobenzene is: Br-C6H4-Br

(e)\C#CCC(C)(C)CC\

To draw the condensed structural formula for this compound, we need to interpret the SMILES notation: C#CCC(C)(C)CC has the IUPAC name: 3-methyl-2-pentyne Next, we will draw the condensed structural formula for 3-methyl-2-pentyne: CH3C≡CCH(CH3)CH2CH3

Key concepts

Chemical Structure Representation

Understanding chemical structures is vital in chemistry. Chemical structure representation is a way of describing the arrangement of atoms within molecules. Scientists and students alike use multiple forms of representations to visualize chemical compounds and understand their properties. The two most common types of chemical structure representation are the condensed structural formula and the full structural formula.

The condensed structural formula simplifies the arrangement by grouping certain atoms together, usually within the same molecule or functional group, making it easier to read and write chemical compounds quickly. On the other hand, the full structural formula provides a more detailed view, showing the exact bonds and arrangement of all atoms. To enhance clarity in communication, a uniform system of naming these structures is essential, which leads us to the International Union of Pure and Applied Chemistry (IUPAC) nomenclature.

SMILES Notation

Another succinct method for representing molecules is through SMILES notation, which stands for Simplified Molecular Input Line Entry System. SMILES strings allow the unique representation of a molecular structure in a single line of characters, which includes atoms, bonds, and other features such as ring structures and branching. This computer-readable format can greatly simplify the storage, retrieval, and processing of chemical information in databases.

For example, take the SMILES string 'CCC=CCC(C)CC' which denotes a specific organic compound. Each 'C' represents a carbon atom, '=' indicates a double bond, and the parentheses denote branching in the molecule. Interpreting SMILES notation requires understanding these conventions, which can be daunting at first but becomes intuitive with practice. It is fascinating how this compact notation encapsulates complex molecular structures and transformations that can easily be converted into more traditional visual structures.

Organic Compound Naming

The naming of organic compounds follows strict rules set by IUPAC to ensure that each compound has a unique and universally understood name. This systematic approach aids in the study and communication of organic chemistry. For example, trans-2-pentene is not just a name but also indicates the compound's structure: a five-carbon alkene (pentene) with a double bond starting on the second carbon in a trans configuration. Similarly, 2,5-dimethyl-4-octene immediately tells you about the presence of methyl groups on certain positions on an octene backbone.

When tackling organic compound naming, consider the length of the carbon chain, the types of bonds (single, double, triple), the presence of substituents, and their respective positions as indicated by the locant numbers. Mastering IUPAC nomenclature rules is essential for students because it enables them to derive a compound's structure just from its name or to name a compound given its structure. Regular practice with examples can help students become adept at these conversions.