Question

Match the structures given in Column-I with the names in Column-II. Column-I Column-II (Compound) (Correct IUPAC name) (A) C=CC(C)Br (P) 4-Bromopent-2-ene (B) C=C(C)CBr (Q) 4-Bromo-3-methylpent-2-ene (C) CC=C(C)C(C)Br (R) 1-Bromo-2-methylbut-2-ene (D) CC=C(C)CBr (S) 1-Bromo-2-methylpent-2-ene

Short answer

The correct matches between the compounds in Column-I and the names in Column-II are as follows: (A, P), (B, Q), (C, R), and (D, S).

Step-by-step solution

Convert SMILES to Lewis structures

Before naming the compounds, let's first draw their Lewis structures from the given SMILES notation: (A) C=CC(C)Br (B) C=C(C)CBr (C) CC=C(C)C(C)Br (D) CC=C(C)CBr

Naming compounds using IUPAC rules

Now, let's name the compounds according to the IUPAC nomenclature rules: (A) The parent chain has 5 carbons with a double bond between carbons 2 and 3, and a bromine atom attached to carbon 4. So, the name is 4-Bromopent-2-ene. (B) The parent chain has 5 carbons with a double bond between carbons 2 and 3, and a bromine atom attached to carbon 3. There's also a methyl group at carbon 3. So, the name is 4-Bromo-3-methylpent-2-ene. (C) The parent chain has 4 carbons with a double bond between carbons 2 and 3, and a bromine atom attached to carbon 1. There's also a methyl group at carbon 3. So, the name is 1-Bromo-2-methylbut-2-ene. (D) The parent chain has 5 carbons with a double bond between carbons 2 and 3, and a bromine atom attached to carbon 1. There's also a methyl group at carbon 2. So, the name is 1-Bromo-2-methylpent-2-ene.

Matching compounds with names

Next, let's match the compounds (A, B, C, and D) with their names (P, Q, R, and S) from Column-II: - (A) 4-Bromopent-2-ene matches with (P) 4-Bromopent-2-ene. - (B) 4-Bromo-3-methylpent-2-ene matches with (Q) 4-Bromo-3-methylpent-2-ene. - (C) 1-Bromo-2-methylbut-2-ene matches with (R) 1-Bromo-2-methylbut-2-ene. - (D) 1-Bromo-2-methylpent-2-ene matches with (S) 1-Bromo-2-methylpent-2-ene. This matching results in the following pairs: (A, P), (B, Q), (C, R), and (D, S).

Key concepts

SMILES notation

SMILES, which stands for Simplified Molecular Input Line Entry System, is a way to represent chemical structures using short ASCII strings. It allows computers and databases to easily understand and manipulate molecular data. The SMILES notation is extremely useful for chemists because it provides a simple, compact way to encode complex structures without the need for graphical images.
For instance:

• The string C=CC(C)Br might look cryptic at first, but it can be broken down as follows:
• 'C' denotes a carbon atom.
• '=' represents a double bond between carbon atoms.
• '(C)' indicates the presence of a side chain, where another carbon is bonded to the main chain.
• 'Br' refers to a bromine atom attached to the structure.

SMILES notation plays a crucial role in cheminformatics and organic chemistry as it allows for efficient searching and sorting of chemical compounds in large databases.

Lewis structures

Lewis structures are diagrams that show the bonds between atoms in a molecule as well as the lone pairs of electrons that may exist. They serve as a more detailed visual representation compared to SMILES notation, aiding in better understanding of how atoms are bonded in a compound.
To draw a Lewis structure:

• Start with the skeletal structure, indicating the arrangement of atoms.
• Represent each covalent bond with a line. If atoms share two pairs of electrons, use a double line, and so on.
• Fill in the valence electrons surrounding each atom. Each line between atoms represents a shared pair of electrons.

For example, with the compound C=CC(C)Br, the Lewis structure helps to highlight the position of the double bond, the side chains, and where the bromine atom attaches to the carbon chain.
Understanding Lewis structures is fundamental in organic chemistry as it reveals the molecule's connectivity and helps predict reactivity and properties based on electron arrangement.

Organic chemistry naming rules

The International Union of Pure and Applied Chemistry (IUPAC) provides a systematic method for naming organic chemical compounds. This ensures consistency and clarity in chemical communication. Naming follows specific rules, making it possible to deduce a compound's structure based on its name.
To name a compound:

• Identify the longest carbon chain to determine the parent name.
• Number the chain to give the substituents the lowest possible numbers.
• Identify and name substituents such as halogens or alkyl groups attached to the main chain.
• Combine these elements, listing substituents alphabetically and indicating the position with numbers.

In our exercise, when naming C=CC(C)Br:

• The main chain is five carbons long – 'pent-.'
• The double bond starts at carbon 2 – 'pent-2-ene.'
• The bromine is attached at the fourth carbon – '4-bromo.'

The result is the name 4-Bromopent-2-ene. Applying these naming rules helps chemists accurately describe chemical structures in a standardized format, facilitating global communication.