What Are Nitro Compounds Definition Types Preparation Methods Reactions and Uses
Nitrogen is necessary for all living beings, and it forms a vital constituent of cells in the form of proteins, DNA, RNA and amino acids. Nitrogen forms complex compounds, such as nitrous oxides and ammonia, which gets used in various industrial and clinical purposes. Mostly, nitro compounds find their applications to produce fertilisers for promoting crop growth.
If you are studying about these complexes, you must not skip learning about nitro compounds properties. Learn related conceptions with great detail to score well in your exams.
What is Nitrogen Compound?
Nitrogen forms many different types of compounds, such as ammonia, nitrous oxides, cyanide, etc. Azides can be inorganic or organic compounds of nitrogen, which comprises of three nitrogen atoms within a group (N3). The compounds comprising of nitrogen arise from a chemical reaction known as nitration, which happens when nitric acts react with an organic compound.
In nature, nitrogen complexes form through various processes, such as nitrification and de-nitrification.
Through nitrification, nitrogen-fixing bacterias present within the soil help in the conversion of ammonia into nitrite. This, in turn, gets converted into nitrates. These complex compounds are taken up by the plants and used in forming animal and plant proteins.
De-nitrification is a process where de-nitrifying bacteria helps in completing the nitrogen cycle through the conversion of nitrate (NO3) back into nitrogen gas (N2). They release nitrogen gas back into the atmosphere from nitrates by removing oxygen.
Read from below about some common types of nitrogen compounds. These include:
Properties of Nitrogen Compounds
Nitrogen compounds occur when nitrous action acts on any organic compound through nitration. Some of the nitro compounds properties are as follows:
Ammonia:
Ammonia, one of the nitrogen consisting compounds, is a colourless gas having a strong, sharp smell.
It has a boiling point of 33.35 degree Celsius and a freezing point of 77.7 degree Celsius along with high vaporisation.
A molecule of ammonia comprises of three atoms of hydrogen and a single nitrogen atom.
Ammonia is a polar molecule attached with strong intermolecular forces due to hydrogen bonding.
Nitrous Oxide:
At normal temperatures, it is heavier than gas having a specific gravity more than 1.53 times.
At room temperature, it exists in a gaseous state, whereas it becomes a liquid after being compressed in a cylinder.
The boiling point of nitrous oxide is -89 degree Celsius, and its density equals to 1.22g/cm3.
At normal temperature, it occurs as a gas without any colour with a sweet smell and taste.
It is also known popularly as laughing gas because when anyone inhales it, produces continuous laughter along with insensibility to pain.
Di-nitrogen oxide is highly insoluble in water and blood.
Moreover, it is not flammable, although it allows the combustion of other materials when it comes in close contact with them.
Nitrate:
Mostly, all nitrate salts get dissolved in water quickly.
Nitrates are nitrogen-based compounds formed due to reduction of a proton from nitric acid (HNO3).
The molecular weight of this nitrogen comprising compounds is 62.005 g/mol.
The number of hydrogen bond donors and acceptors is 0 and 3, respectively.
The di-nitrogen oxide’s exact mass accounts to 61.987818 g/mol same as its mono-isotopic mass.
Nitrites:
Nitrites are nitrogen-based compounds formed because of the deduction of a proton from nitrous acid.
At normal temperatures, it appears as a solution without any colour or crystalline solids.
It is usually denser than water.
When this nitrate compound comes in close contact with eyes, skin or nose, it may result in irritation. It is also harmful if consumed.
The molecular weight of this nitrogen compound accounts to 46.006 g/mol.
Its number of hydrogen bond donor and acceptor equal to 0 and 3 similar to nitrates, respectively.
The exact mass of this nitrogen comprising compound amounts to 45.992903 g/mol similar to its mono-isotopic mass.
The number of nitrites heavy atom is 3, whereas the number of isotope atom amounts to 0.
Urea:
Urea, an organic nitrogen-based compound, forming within the liver, gets dissolved quickly. Usually, minimal amounts of urea get exhibited through human sweat.
The molecular weight of urea (nitrogenous compound) accounts to 60.056 g/mol.
The exact mass of this nitrogen comprising compound equals to 60.032363 g/mol identical to the mono-isotopic mass of urea.
The number of heavy atom amounts to 4, whereas the number of isotope atom amounts to 0.
The complexity of this nitrogen compound amounts to 29.
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Applications of Nitrogen Compounds
Nitrogen-based compounds find various uses. Read these popular applications to know more:
Nitric acid (HNO3) is a compound comprising of nitrogen, used in the manufacture of fertilisers, plastics and dyes.
Pyrazines, a cyclic compound comprising of nitrogen acts as a flavour enhancer of many baked and natural foods. They also add to the aroma in grapes and wines.
Ammonia gets mostly used in the manufacture of fertilisers, and various industrial activities.
Di-nitrogen oxide also gets used as a fuel in most of the food aerosols. In racing automobiles, it gets used in engines.
Nitrous oxide (N2O) also popularly known as laughing gas, gets used for anaesthesia in hospitals and dental applications due to its clinical properties.
Nitric acid also finds its applications in the production of explosives like nitroglycerin. Nitroglycerin is a liquid used in the manufacture of dynamite. Also, it has applications in the military for construction purposes.
Urea, one of the well-known nitro compounds, gets used as a raw material in industries apart from use in fertilisers.
Plants:
Apart from the clinical and industrial applications, nitro compounds also provide benefits to plants. These include:
As soon as nitrogen transforms into complex compounds, plants take these up from the soil to transfer them to other portions. These complexes also find applications in forming macromolecules (proteins and nucleic acids).
One of the primary applications of amines (one of the organic nitrogen compounds) is that it gets used as ammonium salts for promoting the growth of crops. Crops like sugarcane and rice require these salts for steady growth.
It also gets used in the manufacture of chlorophyll in plants which is an essential component for photosynthesis.
Interesting Facts about Chemical Nitrogen and its Compounds
Nitrous oxide is a greenhouse gas, and it is also a potential air pollutant. In terms of weight, it has an impact of 300 times more than carbon dioxide.
Nitrogen is a chemical element having a symbol (N) with a number of isotopes 4.
Nitrous oxide also finds uses in motor racing as it can enhance the power of the engine along with its speed.
Nitrogen has the atomic number 7, and it is a colourless non-metal gas without any odour.
Nitrogen is a tasteless gas present in all living organisms, such as human beings, plants and animals.
Nitrogen gas often gets used in place of carbon dioxide for storage of beer, as it can produce smaller bubble suitable for maintenance of liquor.
Test Your Knowledge
What will be the amine ‘A’ when it acts with nitrous acid exhibiting an oily, yellowish substance?
Aniline
Tri-methylamine
Methylphenylamine
None of these
What will be the formation when aniline reacts with chloroform (under alkaline circumstances)?
Cyanide
Phenyl isonitrile
Isocyanate
None of them
Which of these will not follow azo coupling reaction when it comes with benzene diazonium?
Aniline
Cyanide
Nitrobenzene
None of the above
Organic chemistry is a vast subject. Students often get confused because they do not have in-depth knowledge of the concepts. If you have any doubts related to nitro compounds class 12, just go through the above pointers carefully. You can also visit our website for live classes to understand the problematic concepts of Chemistry clearly. Now you can even download our Vedantu app for better access to these detailed study materials and online sessions.
FAQs on Nitro Compounds Structure Preparation Reactions and Applications
1. What are nitro compounds in chemistry?
Nitro compounds are organic compounds that contain one or more nitro groups (–NO2) directly bonded to a carbon atom. The nitro group consists of one nitrogen atom bonded to two oxygen atoms, commonly represented as –NO2.
Key points about nitro compounds:
- General formula: R–NO2 (where R = alkyl or aryl group).
- The nitro group is strongly electron-withdrawing.
- Examples include nitromethane (CH3NO2) and nitrobenzene (C6H5NO2).
2. What is the functional group of nitro compounds?
The functional group of nitro compounds is the nitro group (–NO2). This group contains one nitrogen atom bonded to two oxygen atoms and attached to a carbon atom of an alkyl or aryl group.
Important features:
- Structure: R–NO2
- It shows resonance between N–O bonds.
- It strongly withdraws electrons by –I (inductive) and –M (mesomeric) effects.
3. How are nitro compounds prepared?
Nitro compounds are commonly prepared by the nitration reaction, where a nitro group (–NO2) is introduced into an organic molecule using concentrated nitric acid. The method depends on whether the compound is aliphatic or aromatic.
Common methods:
- Nitration of alkanes (free radical substitution):
Example: CH4(g) + HNO3(g) → CH3NO2(l) + H2O(l) - Nitration of benzene (electrophilic aromatic substitution):
C6H6(l) + HNO3(l) → C6H5NO2(l) + H2O(l) (in presence of concentrated H2SO4)
4. What is the difference between nitro and nitrite compounds?
The key difference is that in nitro compounds the nitro group (–NO2) is bonded through nitrogen, while in nitrite compounds the –ONO group is bonded through oxygen. This difference in bonding leads to different chemical properties.
Comparison:
- Nitro compound: R–NO2 (bond through nitrogen)
- Alkyl nitrite: R–O–NO (bond through oxygen)
- Example nitro: CH3NO2
- Example nitrite: CH3ONO
5. Why are nitro compounds electron-withdrawing?
Nitro compounds are electron-withdrawing because the –NO2 group exerts strong –I (inductive) and –M (resonance) effects. The highly electronegative oxygen atoms pull electron density away from the carbon chain.
Effects of this electron withdrawal:
- Decreases electron density on adjacent carbon atoms.
- In aromatic rings, deactivates the ring toward electrophilic substitution.
- Directs new substituents to the meta position in electrophilic aromatic substitution.
6. What happens when nitro compounds are reduced?
On reduction, nitro compounds are converted into amines (–NH2). The nitro group (–NO2) is reduced to an amino group under suitable conditions.
Example (reduction of nitrobenzene):
C6H5NO2(l) + 3H2(g) → C6H5NH2(l) + 2H2O(l) (in presence of Ni/Pd catalyst)
Common reducing agents:
- H2/Ni or Pd (catalytic hydrogenation)
- Sn/HCl
- Fe/HCl
7. What are the types of nitro compounds?
Nitro compounds are mainly classified as aliphatic nitro compounds and aromatic nitro compounds based on the carbon group attached to the nitro group.
Types:
- Aliphatic nitro compounds: Nitro group attached to an alkyl chain (e.g., CH3NO2).
- Aromatic nitro compounds: Nitro group attached to an aromatic ring (e.g., C6H5NO2).
8. Why does the nitro group direct to the meta position in benzene?
The nitro group directs substitution to the meta position because it is a strong electron-withdrawing group that destabilizes the ortho and para carbocation intermediates. Its –I and –M effects reduce electron density most strongly at the ortho and para positions.
As a result:
- Ortho and para intermediates are less stable.
- The meta intermediate is relatively more stable.
9. What are the common uses of nitro compounds?
Nitro compounds are widely used in the manufacture of explosives, solvents, dyes, and pharmaceuticals. Their chemical reactivity and high energy content make them industrially important.
Major uses:
- Explosives: Trinitrotoluene (TNT)
- Solvents: Nitromethane
- Dye intermediates: Nitrobenzene derivatives
- Pharmaceuticals: Precursors to aromatic amines
10. Can you give an example of a nitration reaction of benzene?
An example of nitration of benzene is the formation of nitrobenzene by reacting benzene with concentrated nitric acid in the presence of concentrated sulfuric acid. This is an electrophilic aromatic substitution reaction.
Balanced equation:
C6H6(l) + HNO3(l) → C6H5NO2(l) + H2O(l)
Key points:
- H2SO4 generates the NO2+ (nitronium ion).
- The reaction occurs at about 50–60°C.
- The product is nitrobenzene, an aromatic nitro compound.
