PRODUCT IDENTIFICATION

CLASSIFICATION

PHYSICAL AND CHEMICAL PROPERTIES

clear to yellowish liquid

AUTOIGNITION

REFRACTIVE INDEX

80 C

APPLICATIONS

Nitrobenzene (also called nitrobenzol ) is a colourless to pale yellow, oily, highly toxic liquid with the odour of bitter almonds. Nitrobenzene is manufactured commercially by nitration of benzene (also a common air pollutant) using a mixture of nitric and sulfuric acids. Commercially nitrobenzene can be either produced in a batch or by a continuous process. Both batch and continuous processes employing mixed nitric and sulfuric acids are used to make nitrobenzene. The continuous process is favored over the batch process because its production capacity is much larger, it has lower capital costs and it entails more efficient labor usage. Reactors for the continuous process also usually utilized lower nitric acid concentrations, are smaller with more rapid and efficient mixing, and therefore have higher reaction rates. Nitrobenzene undergoes nitration, halogenation, and sulfonation much more slowly than does benzene. It may be reduced to a variety of compounds, depending on the reaction conditions. Most nitrobenzene produced is reduced to aniline; smaller amounts are converted to azobenzene, hydrazobenzene (the intermediate for benzidine), and phenylhydroxylamine. Reduction of both the nitro group and the benzene ring affords cyclohexylamine. Nitrobenzene is used as a mild oxidizing agent in the syntheses of quinoline and fuchsin. Nitrobenzene is used to produce lubricating oils such as those used in motors and machinery. Nitrobenzene and its derivatives are used in the manufacture of dyes, drugs, pesticides, polisher, paint, and synthetic rubber. 

The prefix nitro- indicates the presence of NO₂^- radical, while nitrate refers to any salt or ester of nitric acid or the NO₃^- anion. Nitroso- is the prefix indicating presence of the group -NO and azo- is for -N=N- group. Some range of  organic compounds containing nitrogen include nitro compounds (RNO₂ ), nitroso compounds (RNO), amines (R₃N ), amino acids, and natural alkaloids or nucleotides. The nitrogen ion in nitro compounds is trigonally planar with 120° angles. There are two resonance bonds so that the two oxygens are equivalent. Nitro compounds are strongly basic due to electron withdrawing both inductively and mesomerically. Historically, they are abundant in dyes and explosives. Nitro compounds, organic hydrocarbons having one or more NO₂ groups bonded via nitrogen to the carbon framework, are versatile intermediate in organic synthesis.

• Michael addition
• Reduction
• Henry Reaction (Nitro-aldol reaction)
• Nef reaction
• O-Alkylation
• Cycloaddition
• Substitution, Elimination, Conversion reaction
• Alkylation, Acylation, and Halogenation

When substituted benzene molecules undergo electrophilic substitution reactions, substituents on a benzene ring can influence the reactivity. Activating substituents that activate the benzene ring toward electrophilic attack can alter the reaction rate or products by electronically or sterically affecting the interaction of the two reactants. deactivating substituents removes electron density from the benzene ring, making electrophilic aromatic substitution reactions slower and more difficult than benzene itself. For example, a hydroxy or methoxy substituent in phenol and anisole increases the rate of electrophilic substitution, while a nitro substituent decreases the ring's reactivity. Electron donating substituents activate the benzene ring toward electrophilic attack, and electron withdrawing substituents deactivate the ring, making it less reactive to electrophilic attack. The strongest activating substituents are the amino (-NH₂) and hydroxyl (-OH) groups.

Reactivity Effects	Activating substituents	Deactivating substituents
Strong	-NH2, -NHR, -NR2, -OH, -O-	-NO2, -NR3+, -CF3, CCl3
Moderate	-NHCOCH3, -NHCOR, -OCH3,-OR	-CN, -SO3H, -COOH, -COOR, -COH, -COR
Weak	-CH3, -C2H5, -R, -C6H5	-F, -Cl, -Br, -I

Toluene, aniline and phenol are activated aromatic compounds. Examples of deactivated aromatic compounds are nitrobenzene, benzaldehyde and halogenated benzenes.

Activating substituents generally direct substitution to the ortho and para positions where substitutions must take place. With some exceptions, deactivating substituents direct to the meta position. Deactivating substituents which orient ortho and para- positions are the halogens (-F, -Cl, -Br, -I) and -CH₂Cl, and -CH=CHNO₂

When disubstituted benzene molecules undergo electrophilic substitution reactions, a new substituent is directed depends on the orientation of the existing substituents and their individual effects; whether the groups have cooperative or antagonistic directing effects. Ortho position is the most reactive towards electrophile due to the highest electron density ortho positions. But this increased reactivity is countervailed by steric hindrance between substituent and electrophile.

A nucleophilic substitution is a substitution reaction which the nucleophile displaces a good leaving group, such as a halide on an aromatic ring. This mechanism is called S_NAr ( the two-step addition-elimination mechanism), where electron withdrawing substituents activate the ring towards nucleophilic attack. Addition-elimination reactions usually occur at sp² or sp hybridized carbon atoms, in contrast to S_N1 and S_N2 at sp^3. Chloro and bromobenzene reacts with the very strong base sodium amide (NaNH₂) to give good yields of aniline. Other nucleophilic aromatic substitution mechanisms include benzyne mechanism and free radical (S_RN1) mechanism.

• Conversion of halogens into other various substituents
• Modifying activating substituents
• Oxidative degradation of alkyl chain
• Reduction of nitro or carbonyl substituents
• Reversibility of the aromatic sulfonation reaction

APPEARANCE

clear to yellowish liquid

99.0% min