Name each disubstituted benzene.

Name: Problem 65, Chapter 21: Chemistry A Molecular Approach
Uploaded: 2019-07-26T01:10:38-08:00
Duration: 8 min 10 s
Channel: Eszter Pos
Description: Name each disubstituted benzene.

Key Concepts

Common Nomenclature (Ortho, Meta, Para)

The common naming system for disubstituted benzenes uses the terms ortho (o-), meta (m-), and para (p-) to describe the relative positions of the substituents on the benzene ring. This naming convention is a quick way to describe the structure of the compound before applying systematic IUPAC nomenclature.

Positional Isomerism

Positional isomerism in disubstituted benzenes refers to the different possible arrangements of substituents on the benzene ring. These arrangements are typically referred to as ortho (adjacent positions, 1,2-), meta (separated by one carbon, 1,3-), and para (opposite sides, 1,4-), which are critical for both IUPAC and common nomenclature.

IUPAC Nomenclature

The IUPAC nomenclature system provides a standardized method for naming disubstituted benzenes by assigning numerical positions to the substituents on the benzene ring. Using locants such as 1,2-, 1,3-, and 1,4- ensures clarity and consistency in communication about these molecules.

Benzene Structure

Benzene is a six-membered carbon ring with alternating double bonds, which can be represented as a structure where electrons are delocalized over the entire ring. This structure is fundamental in organic chemistry, particularly when discussing how different substituents affect the chemical properties of the molecule.

Disubstituted Benzene

A disubstituted benzene contains two substituents attached to the benzene ring. The positions of these substituents relative to each other significantly impact the chemical and physical properties of the molecule, making it necessary to distinguish between the different isomers.

Aromatic Compounds

Aromatic compounds are a class of compounds characterized by conjugated ring systems with delocalized ?-electrons that provide enhanced stability. Benzene is the prototypical aromatic compound, and its unique electronic structure is key to understanding the behavior of its substituted derivatives.

Transcript

00:01 Welcome everyone.

00:02 My problem was problem 65 from the book a molecular approach.

00:07 This is a chemistry book.

00:09 Chapter 21 is focused on organic chemistry, the basics of organic chemistry.

00:15 And problem 65 is also an organic chemistry problem.

00:21 So the task is to name three die -substituted benzene molecules compounds.

00:27 So let's just get started.

00:30 The first one here, you can see we have two bromine atoms attached to the benzene ring.

00:40 This is a bromine atom and this is also a bromine atom.

00:43 They are substituted, as you see, towards the opposite sides of the benzene molecule.

00:50 So the first step that we have to do is we have to number the carbon atoms to which the bromine atoms or the substitutions are attached.

01:00 So when we do this, we have to start a substituted carbon atom, where the hydrogen is substituted to another atom.

01:11 So this, in case, we start randomly.

01:14 The two bromine atoms are identical, so we can start with any of them.

01:18 So we are going to start with this one.

01:22 So this is going to be the first carbon atom, the second carbon atom, the third carbon atom, the fourth carbon atom, also having a substitute.

01:31 The hydrogen attached to the carbon atom originally has been substituted to a bromine atom.

01:38 And the fifth and the sixth carbon atoms are not substituted.

01:43 I mean, the hydrogens are not substituted.

01:48 Now, obviously, one can start the numbering in this direction, or one can start the numbering in this direction.

01:58 How do we decide? well, in this case, the result is identical, because then we would call this one the first one, the second one, sorry, the first one would be the same, the second one would be this, the third one would be this, the fourth one would be the substituted again, the fifth one and the sixth one would be the originally, i called them third one and second one carbon atom.

02:24 Always you have to start the numbering towards the other substituent.

02:32 So that you decrease the sum of the numbers in the name of the compound.

02:40 So how do we name this compound? it's a 1 -4 -di -bromo benzene.

02:46 Now it's a benzene substitute.

02:49 So now we understand why is it called benzene.

02:54 It's di -bromo because as we discussed we have 1 -2.

02:59 So di -2 -brombo -substituent.

03:03 And it is one -four because it's the fourth and the first carbon atoms that are substituted.

03:13 Let's go to the next question.

03:16 So question b, we have two identical substitutes again, but in this case they are not halogenes, they are ethel groups, and they are located differently.

03:29 So we have to do the steps again.

03:31 We will just number the carbon atoms...

Please give Ace some feedback