Halogenation and Nitration

Introduction 

Halogenation is a chemical reaction in which halogen atoms replace hydrogen atoms in a molecule. The end product of halogenation is a chemical reaction that differs from the beginning component in terms of characteristics. Any halogen elements, such as fluorine, chlorine, bromine and iodine can halogenate water. Halogenation is essential in the research of water treatment and fire retardants in the setting of corrosion. The nitration process is a chemical reaction in which a nitro group (NO2) is introduced into an organic chemical molecule. Let us take a closer look at it now.

Halogenation is a chemical reaction in which halogen atoms replace hydrogen atoms in a molecule. Halogenation can occur using any halogen elements, i.e., fluorine, chlorine, bromine, iodine and astatine. Halogens occupy the seventh column in the periodic table. The resulting product of a halogenation compound reaction is known as a halogenated compound.

• Fluorine>chlorine>bromine>iodine is the sequence of halogen reactivity.
• Fluorine is the most stable halogen; removing a fluorine atom once added is difficult.
• The reaction is also influenced by the type of the halogenated substrate molecule.
• Halogenation reactions may require a catalyst to boost the electrophilicity of the halogen.

Halogenation of alkanes

When a halogen combines with an alkane in the presence of ultraviolet (UV) radiation or heat, a haloalkane is generated (alkyl halide). The chlorination of methane is one such example. 

When an alkane is halogenated, one or more halogen atoms are swapped for hydrogen atoms, resulting in a hydrocarbon derivative. Because they are non-polar and lack functional groups at which reactions can occur, alkanes are notoriously unreactive molecules. As a result, free radical halogenation provides a mechanism for functionalising alkanes. The amount of identical C-H bonds found in all but the simplest alkanes is a severe constraint of radical halogenation, making selective reactions challenging to execute. The halogenation of alkanes is an example of a substitution reaction, which is common in organic chemistry. A substitution reaction is a chemical reaction in which one atom or a group of atoms on a hydrocarbon or hydrocarbon derivative is replaced by a part of a tiny reactive molecule.

Nitration

Nitration is a term used in organic chemistry to describe a set of chemical processes that add a nitro group to an organic molecule. The phrase is often wrongly applied to the numerous processes of nitrate ester formation between alcohols and nitric acid (as occurs in the synthesis of nitroglycerin). The fundamental distinction between nitrates and nitro compounds is that the nitrogen atom establishes a chemical connection with a non-oxygen element such as carbon or other nitrogen atoms in the final structure. 

Organic nitrates’ nitrogen atom is usually connected to an oxygen atom bound to carbon. In nitro compounds, the nitrogen atom is directly linked to a non-oxygen atom. In contrast, the nitrogen atom in nitrates is bonded to a non-oxygen atom (usually carbon or another nitrogen atom). There are numerous industrial applications of nitration; the most important by volume is the synthesis of nitroaromatic chemicals like nitrobenzene. Nitration reactions are commonly utilised to create explosives.

Under certain conditions, alkanes react with nitric acid, a hydrogen atom being replaced by a nitro-group, NO2. This process is known as nitration. Nitration of the alkanes may be carried out in the vapour phase between 150° and 475 °C, to obtain a complex mixture of mononitro alkanes.

Nitration of Benzene

Nitrobenzene is an essential aromatic nitro chemical utilised as a solvent and an intermediary in producing a wide range of organic compounds. The majority of nitrobenzene produced is converted to aniline, which has numerous applications. The process of nitrating benzene for the commercial manufacturing of nitrobenzene (NB) is well-known.

When a nitro group replaces one (or more) hydrogen atoms on the benzene ring, NO2 nitration occurs. At a temperature of not more than 50°C, benzene is treated with a solution of concentrated nitric acid and concentrated sulfuric acid. The mixture is kept at this temperature for roughly half an hour, and nitrobenzene, a yellow greasy gas, is generated.

Because concentrated sulfuric acid serves as a catalyst, it is not included in the equations. There is a higher probability of getting more than one nitro group replaced on the ring at higher temperatures. Even at 50°C, a considerable amount of 1,3-dinitrobenzene will occur. Some of the generated nitrobenzenes react with the nitrating combination of concentrated acids, forming nitrobenzene. The new nitro group is placed in the third position on the ring. New groups are “directed” into nitro groups.

Conclusion

Halogenation reactions occur both in bulk and in fine chemical synthesis. The products and intermediates produced by halogenation find application in pharmaceuticals, polymers and plastics, refrigerants, fuel additives, fire retardants and agro products. In medicines, adding fluorine or chlorine atoms to a molecule can boost its medicinal potential. Organobromides and organoiodines are also present in nitro compounds. The intermediate molecules allow functional groups to a substrate and synthesise more complicated structures. Nitration replaces a hydrogen atom with one or more nitro groups in an organic molecule (single bond NO2).