3,5-Dinitrobenzoic acid

Light yellow crystalline powder

Fixed

1.683 g · cm -3

204-206 ° C

2.82 (25 ° C)

• Soluble in ethanol (50 g / l)
• Poorly soluble in water ( 1.350 g / l (25 ° C))
• Almost insoluble in benzene, diethyl ether and carbon disulfide

Attention

1800 mg · kg -1 ( LD50, rat, oral)

Template: Infobox chemical / molecular formula search available

The 3.5 - dinitrobenzoic is an organic chemical compound and is one of the aromatics. The structure consists of a benzene ring with an added carboxy group (-COOH) and two nitro groups (- NO2) as a substituent. It is derived from both the benzoic acid as well as from nitrobenzene and dinitrobenzene and belongs to the group of Dinitrobenzoesäuren. The 3.5 - dinitrobenzoic is mainly used in the analysis of organic substances.

Representation

3.5 dinitrobenzoic obtained from benzoic acid by reaction with fuming nitric acid in the presence of concentrated sulfuric acid.

Another way is the nitration of 3 -nitrobenzoic acid with a mixture of nitric acid with fuming sulfuric acid, with yields of about 98%.

Properties

3.5 dinitrobenzoic is an odorless, yellowish solid with a melting point of 204-206 ° C. It has due to the -M effect of the two nitro groups to a higher acidity compared to benzoic acid and the nitrobenzoic acids. The pK a value of 2.82 is therefore correspondingly lower ( benzoic acid: 4,20 ).

Use

The 3.5 - dinitrobenzoic is mainly used in the analysis of organic substances by derivatization. Liquid substances or those with a low melting point can be converted to a slightly crystallized derivatives: alcohols can be identified, for example by measuring the melting points of its esters of 4-nitrobenzoic acid, or 3,5- dinitrobenzoic. For this purpose the substance to be analyzed is reacted with 3,5-dinitrobenzoic acid in the presence of small amounts of sulfuric acid.

The melting points of these derivatives are usually sharp. This reaction is also suitable for many amines.

The derivatives of 3,5- dinitrobenzoic generally have higher melting points than that of 4-nitrobenzoic acid. You are then preferably selected when the melting point of 4-nitrobenzoic acid is too low and no more accurate determination is possible.

If the substance in question is more sensitive, and instead they direct reaction with the corresponding acid chloride, the 3,5- dinitrobenzoyl chloride. In this way, for example, derivatives of amino acids are available.