Q18) Which of the following statements is false for the compound, phenol? (Note that toluene by itself is retained by the IUPAC nomenclature, but its derivatives, which contains additional substituents on the benzene ring, might be excluded from the convention). Similarly, an arene named as a substituent is called an aryl group. a) Cyclohexanol Many simple monosubstituted derivatives of benzene have common names of long stand- ing that have been retained in the IUPAC system.
Many have been synthesized in the laboratory, and several of the others are products of com- bustion. To this phenomenon, we can name compounds formed this way by applying this rule: (phenyl + substituent). Alternatively, we can use the numbering system to indicate this compound.
Some common substituents, like NO2, Br, and Cl, can be named this way when it is attached to a phenyl group.
Under this consideration, the above compound can be named: 2,4-difluorobenzyl chloride.
Naphthalene is bicyclic (has two rings), and its two benzene rings share a common side. Similar to the base name nomenclatures system, the carbon in which th base substitutent is attached on the benzene ring is given the first priority and the rest of the substituents are given the lowest number order possible. c) 4,5-difluorobenzyl bromide
Many simple monosubstituted derivatives of benzene have common names of long stand- ing that have been retained in the IUPAC system.
In these examples the base name of the benzene derivative determines the carbon at which numbering begins: anisole has its methoxy group at C-l, toluene its methyl group at C-l, and aniline its amino group at C-1. Q8) TNT’s common name is: ______________________________.
e) Bleach
Thus, each of the following examples is named as a 1,2,4-trisubstituted derivative of benzene rather than as a 1,3,4-derivative: When the benzene ring is named as a substituent, the word phenyl stands for C6H5–. In fact, a large number of medicinal compounds are likely to feature a benzene ring somewhere in their structure, though these compounds are often more complicated than those shown here. Several billion kilograms of polystyrene are produced per year, and its uses include plastic cutlery, food packaging, foam packing materials, computer housings and insulation materials. Figure 13.6 "Some Benzene Derivatives" shows four examples.
Benzene derived products are well known to be pleasantly fragrant. The naming of benzene derivatives can seem a little confusing to those new to organic chemistry. True.
The structural formulas of naphthalene, anthracene, and phenanthrene are shown along with the numbering system used to name their substituted derivatives: In general, the most stable resonance structure for a polycyclic aromatic hydro- carbon is the one with the greatest number of rings that correspond to Kekule formulations of benzene. Transformation of 1,3-dichlorobenzene into m-dichlorobenzene.
Characteristic properties of chemical compounds and complex formation, 8. The benzyl group (abbv. Some examples are; mono substituted Benzene derivatives Nomenclature of di or polysubstituted benzene. Benzo[a]pyrene, for example, is present in tobacco smoke, contaminates food cooked on barbecue grills, and collects in the soot of chimneys. Nomenclature of 2,4-difluorobenzyl chloride. One of the most obvious is polystyrene, manufactured through the polymerisation of styrene. Q13) (True/False) Benzyl chloride can be abbreviated Bz-Cl.
Only substituents phenol, benzoic acid, and benzaldehyde share this commonality.
In conclusion, these can be pieced together into a summary diagram, as shown below: In addition to simple benzene naming and OMP nomenclature, benzene derived compounds are also sometimes used as bases. Notice how camphor lacks the benzene ring to be “aromatic”. All compounds that contain a benzene ring are aromatic, and substituted derivatives of benzene make up the largest class of aromatic compounds. An example showing phenol as a base in its chemical name.
There are three xylene isomers, the ortho (o)-, meta (m)-, and para (p)- substituted derivatives. For a modern, chemical definition of aromaticity, refer to sections Aromaticity and Hückel’s Rule. Q2) Benzene unusual stability is caused by how many conjugated pi bonds in its cyclic ring? The common name 2,4-dibromophenol, is shared by the IUPAC systematic nomenclature.
b) phenylamine Some … Figure 10. By looking for the longest chain in the compound, it should be clear that the longest chain is eight (8) carbons long (octane, as shown in green) and that a benzene ring is attached to the second position of this longest chain (labeled in red). See the site’s content usage guidelines. He was able to determine that the unknown compound contains a cyclic ring in its structure as well as an alcohol (-OH) group attached to the ring. Figure 19. […] Link: Benzene Derivatives in Organic Chemistry | Compound Interest […], […] names, which can be confusing; here we’ve a infographic of benzene derivatives from Compound Interest, in which common names of benzene derivatives are shown primarily, with systematic names shown in […], […] Benzene is a hugely important compound in organic chemistry. A benzyl group is C6H5CH2-.
Phenol, Ph-OH, or C6H5OH, for example, is formed when an alcohol (-OH) group displaces a hydrogen atom on the benzene ring. Compounds that contain benzene rings in their structures are commonly referred to as ‘aromatic compounds’.
Many such compounds are named by attaching the name of the substituent as a prefix to benzene. Eugenol, an aromatic compound extracted from clove essential oils. […], You forgot the thiophenols (AKA benzene thiol, phenylthiol). Dimethyl derivatives of benzene are called xylenes. Many aromatic compounds are however, sweet/pleasant smelling. Whilst the criteria for a compound to be termed aromatic are a little more complicated than this, it serves as a serviceable, simple definition. See Nomenclature of Organic Compounds for a review on naming organic compounds. It is converted in the liver to an epoxy diol that can induce mutations leading to the uncontrolled growth of certain cells. Q9) Name the following compound using OMP nomenclature: Q10) Draw the structure of 2,4-dinitrotoluene. Figure 5.
d) Phenol can be used as a catalyst in the hydrogenation of benzene into cyclohexane. Note how benzene no longer serves as a base when an OH group is added to the benzene ring. Mono-substituted Benzene Compounds. For this reason, the common chemical name 2,4,6-trinitrotoluene, or TNT, as shown in Figure 17, would not be advisable under the IUPAC (systematic) nomenclature. e) 5,6-difluoroethyl bromide
Anthracene has three rings fused in a “linear” fashion; an “angular” fusion characterizes phenan- threne.
The general format for this kind of naming is: (positions of substituents (if >1)- + # (di, tri, …) + substituent)n + benzene.
For example, chlorine (Cl) attached to a phenyl group would be named chlorobenzene (chloro + benzene).
The Figure to the left shows the two resonance forms of benzene. For this reason, the OMP system will yield common names that can be converted to systematic names by using the same method as above.
Since there is only one substituent on the benzene ring, we do not have to indicate its position on the benzene ring (as it can freely rotate around and you would end up getting the same compound.).
Other names such as toluene, styrene, naphthalene, or phenanthrene can also be seen in the IUPAC system in the same way.
Polymerisation involves the reaction of many smaller molecules to form long chains of molecules. c) Phenol
They are all present in coal tar, a mixture of organic substances formed when coal is converted to coke by heating at high temperatures (about 1000 C) in the absence of air. This is due to the fact that a number of them still have ‘common’ names that are still frequently used, or even preferred, over their IUPAC names.
(Note that toluene by itself is retained by the IUPAC nomenclature, but its derivatives, which contains additional substituents on the benzene ring, might be excluded from the convention). There is a misconception amongst the scientific community, however, that all aromatics are sweet smelling and that all sweet smelling compounds would have a benzene ring in its structure. Why or why not?
No reaction, benzene requires a special catalyst to be hydrogenated due to its unusual stability given by its three conjugated pi bonds. Alternatively, the circle within the benzene ring can also be dashed to show the same resonance forms (#4). In order to stabilize this structure, 3 conjugated π (double) bonds are formed in the benzene ring in order for carbon to have four adjacent bonds.
d) Methanol Using toluene as the example, the ortho orientation is the 1,2 relationship; the meta is 1,3 and the para is 1,4. This terminology derives from the fact that they are often have a pleasant and sweet fragrance (although benzene itself does not), but the more modern definition of the word relates to the the structure of molecules. They are defined as the following: Using the same example above in Figure 9a (1,3-dichlorobenzene), we can use the ortho-, meta-, para- nomenclature to transform the chemical name into m-dichlorobenzene, as shown in the Figure below. Common benzene derived compounds with various substituents. The concept of a base is similar to the nomenclature of aliphatic and cyclic compounds, where the parent for the organic compound is used as a base (a name for its chemical name.
c) Phenol is highly toxic to the body even in small doses.
A large number of polycyclic aromatic hydrocarbons are known.
This is best illustrated in the diagram below.
f) Cannot determine from the above information.
Since the carbons in the cyclohexane ring is fully saturated with hydrogens (carbon is bound to 2 hydrogens and 2 adjacent carbons), no double bonds are formed in the cyclic ring. Click to enlarge Benzene is a hugely important compound in organic chemistry.
Figure 3. In order to correctly name TNT under the IUPAC system, the simple benzene naming system should be used: Figure 18. The correct abbreviation for Benzyl chloride is Bn-Cl.
Q17) A scientist has conducted an experiment on an unknown compound.
Figure 4.
While the use of other common names are usually acceptable in IUPAC, their use are discouraged in the nomenclature of compounds.