Ask about the color of nitro after it is reduced to an amino group

This post,The time interval has been long.,I don't know if it helps? Iron powder reduction and hydrogenation reduction products, I don't know if you have analyzed them in detail? In fact, it is caused by different reaction mechanisms, different side reactions, that is, different by-products.

There are few by-products of iron powder reduction, but the reaction of nitro substance is not complete, and there are few color-based products; There are many side reactions of hydrogenation reduction, and there are many color group products, especially azo, oxidized azo, hydrogenated azo, and even halogens.

group, there are a large number of dehalogenated products, which directly affect the appearance, but the purity can be ensured to be very high. If it is rectified, the low boiling matter and the high boiling substance can be removed, and the color becomes light or colorless. Of course, all amino substances will gradually darken in color when they come into contact with air, and the effect of high temperatures will be greater.

The general color will become darker, if the melting point is not too high, you can use the decompression method to steam out to see, I have done an experiment of nitro reduction amino group before, the color of the product is brown, and it is off-white after decompression evaporation!

It's normal for the color to get darker, as long as you purify it a little bit and look for it, it's just that it contains some pigments, and these problems don't need to be so bothered.

The specific methods of nitro reduction into sales amino are: metal reduction method, catalytic hydrogenation reduction method.

1. Metal reduction method.

Reduced with metal and hydrochloric acid, commonly used metals are zinc, iron, etc., which are suitable for acid-stable compounds.

2. Catalytic hydrogenation reduction method.

With catalytic hydrogenation, such as PT, Ni, etc., only nitro can be reduced with mild reduction (slightly pressurized at room temperature). There are also some characteristic reduction reactions of nitrobenzene, such as the reduction of zinc to phenyl hydroxylamine under weakly acidic conditions; Reduced under alkaline conditions, aqueous solution to obtain azobenzene, alcohol solution to obtain hydrogenated azobenzene.

It should be noted that the various reaction transition states in nitro reduction, such as nitroso, azo, ammonia, etc. are inevitable, and many reaction points can usually be seen when tracking the reaction, and the reaction time is usually appropriately extended (and it is recommended to reduce the reaction temperature), and these intermediates will generally be basically reduced completely, if it is not possible, you can consider changing the hydrogenation conditions, such as pd c for catalyst (although its activity will be reduced under alkaline conditions), hydrazine for hydrogen, etc.

The essence of nitro

Nitro refers to the group left after removing one hydroxyl group from the nitric acid molecule, and the compound where the nitro group is attached to other groups (mainly hydrocarbon groups) is called nitro compound.

Nivu (especially aromatic nitro compounds) is toxic, and the introduction of multiple nitro groups into the molecule not only increases the toxicity, but also enhances the oxidation, and most of them become the most important substances. It is a functional group of nitro compounds, and it also contains nitro in nitrates.

Nitro is another chromophore, which can deepen the color of chromogen; Some drugs introduce nitro groups to enhance antimicrobial properties; The reaction of introducing nitro groups into organic molecules (and a few inorganic molecules) is called nitrification. Trinitrotoluene is commonly known as: TNT, which is a light yellow solid and easy to **.

The above content refers to Encyclopedia-Nitro.

Summary. The reduction reaction of nitro compounds is a chemical reaction in which the nitro group is separated from the nitro compound, making it a non-nitro compound. This reaction is usually achieved by oxidizing agents such as hydrogen peroxide, red copper, halides or reducing agents such as sodium or potassium.

In this reaction, the oxidant separates the nitro group from the nitro compound, while the reducing agent removes oxygen. The general equation for the reduction reaction of nitro compounds is: R-NO2 + 2H+ +2E- R-H + H2O

To the equation. The reduction reaction of nitro compounds is a chemical reaction in which the nitro group is separated from the nitrate-based hood segment complex to become a non-stuffy nitro compound. This reaction is usually achieved by oxidizing agents such as hydrogen peroxide, red copper, halides or reducing agents such as sodium or potassium.

In this reaction, the oxidant separates the nitro group from the nitro compound, while the reducing agent removes oxygen. The general formula for the reduction reaction of nitro compounds is: R-NO2 + 2H+ +2E- R-H + H2O

Butanol, propionaldehyde, 3-pentanone, cyclohexanone, glutaric acid, glycerin, o-methylphenol methyl, acethylamine, benzoic acid, ethyl benzoate, propanol, propyl chloride 2-methylbutyraldehyde, thiobium, dextrose, n,n-dimethylaniline, acetic acid structure.

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Butanol: CH3CH2OH Propionaldehyde: CH3CH3CH 3-pentanone:

ch3ch2coch3 cyclosedan ketone: C5H10O glutaric acid: Hoocch2C2Cooh glycerol:

C3H8O3 o-methylphenol: C6H5C(CH3)2OH Methyl ether: R-O-R ethylamine:

NH2CH2CH3 Pyridine:C5H5N Benzoic Acid:C6H5CO2H Ethyl Benzoate:

C6H5CoOC2H5 Propanol:CH3CH2OH Propionyl Chloride:ClCoCH3 2-Methylbutyraldehyde:

ch3coch2cho thienesan: c4h4s azole: c4h4n2 glucose:

C6H12O6 N,N-Dimethylaniline:C7H9N acetic acid:HCOOH

The reduction of nitro to amino usually requires the use of a reducing agent. The more common reducing agents are sodium bisulfite and sodium hydroxide zinc powder. The reduction of nitro groups to amino groups is mainly used in organic chemistry, for example in the synthesis of drugs and dyes.

The reduction of nitro using sodium bisulfite needs to be carried out under acidic conditions, generally using acetic acid or hydrochloric acid as an acid catalyst. After the reduction reaction, the product can be separated by extraction or separating funnel and then purified by distillation or crystallization.

When sodium hydroxide zinc powder reduces nitro, it needs to be carried out under alkaline conditions. The reaction is similar to sodium bisulfite reduction, and the product can be separated and purified by the same method.

It should be noted that it is crucial to maintain the stability of the reaction temperature and the correct use of catalysts when the land fiber is performing the nitro reduction reaction. During the reaction, it is also necessary to pay attention to the control of the reaction rate and the stability of the product.

In addition, there are other reducing agents that can also be used for nitro reduction, such as nitrite, oral isopropyl acetate, etc. The selection of the appropriate reducing agent and reaction conditions depends on the specific requirements and purpose of the reaction.

In summary, the conditions for the reduction of nitro to amino groups generally require the use of reducing agents, which are carried out under acidic or alkaline conditions, while paying attention to the reaction temperature and the use of catalysts, as well as the separation and purification of the products. <>