3,5-dinitrobenzoic acid

Structural formula
General
Surname	3,5-dinitrobenzoic acid
Molecular formula	C 7 H 4 N 2 O 6
Brief description	light yellow crystalline powder
External identifiers / databases
EC number	202-751-1
ECHA InfoCard	100.002.501
PubChem	7433
Wikidata	Q223027
properties
Molar mass	212.12 g mol −1
Physical state	firmly
density	1.683 g cm −3
Melting point	204-206 ° C
pK s value	2.82 (25 ° C)
solubility	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 ;
safety instructions
GHS labeling of hazardous substances Caution
H and P phrases	H: 302-315-319-335-413
	P: 261-305 + 351 + 338
Toxicological data	1800 mg kg −1 ( LD 50 , rat , oral )
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

The 3,5-dinitro benzoic acid is an organic chemical compound and one of the aromatics . The structure consists of a benzene ring with an attached carboxy group (-COOH) and two nitro groups (-NO ₂ ) as substituents . It is derived from benzoic acid as well as from nitrobenzene or dinitrobenzene and belongs to the group of dinitrobenzoic acids . 3,5-Dinitrobenzoic acid is mainly used in the analysis of organic substances.

presentation

3,5-Dinitrobenzoic acid is 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 acid is an odorless, yellowish solid with a melting point of 204-206 ° C. Due to the −M effect of the two nitro groups, it has a higher acidity compared to benzoic acid and nitrobenzoic acids . The pK _s value of 2.82 is therefore correspondingly lower (benzoic acid: 4.20).

use

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

Detection of isopropanol as a derivative of 3,5-dinitrobenzoic acid:
3,5-dinitrobenzoic acid-2-propyl ester (melting point: 123 ° C.).

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

The derivatives of 3,5-dinitrobenzoic acid generally have higher melting points than those of 4-nitrobenzoic acid. They are preferred when the melting point of 4-nitrobenzoic acid is too low and an exact determination is no longer possible.

If the substance in question is more sensitive, the direct reaction with the corresponding acid chloride , 3,5-dinitrobenzoyl chloride , takes place instead . In this way z. B. derivatives of amino acids also accessible.

Individual evidence

↑ ^a ^b ^c ^d ^e ^f data sheet 3,5-Dinitrobenzoic acid, 99% from Sigma-Aldrich , accessed on March 7, 2017 ( PDF ).
↑ ^a ^b ^c data sheet 3,5-Dinitrobenzoic acid, 99% from Acros, accessed December 25, 2013.
↑ ^a ^b ^c ^d CRC Handbook of Tables for Organic Compound Identification , Third Edition, 1984, ISBN 0-8493-0303-6 , p. 206.
↑ ^a ^b B. C. Saunders, GJ Stacey, IGE Wilding: The Preparation of 3: 5-Dinitrobenzoic Acid and 3: 5-Dinitrobenzoyl Chloride - Observations on the Acylation of Amino-acids by means of 3: 5-Dinitrobenzoyl Chloride and certain other Acid Chlorides ; in: Biochem. J. , 1942 , 36 (3-4), pp. 368-375, PMID 16747534 ; PMC 1265703 (free full text).
^ RQ Brewster, Bill Williams, Ross Phillips: 3,5-Dinitrobenzoic Acid In: Organic Syntheses . 22, 1942, p. 48, doi : 10.15227 / orgsyn.022.0048 ; Coll. Vol. 3, 1955, p. 337 ( PDF ).
^ BA Lebedev, V. Yu. Dolmatov, PS Zubarev, NV Latynov, MM Aleksandrov, RI Ponamareva: Preparation of 3,5-dinitrobenzoic acid from meta-nitrobenzoic acid ; in: Pharmaceutical Chemistry Journal , 1988 , 22 (5), pp. 399-401, doi : 10.1007 / BF00769656 .

Web links

Entry to 3,5-dinitrobenzoic acid . In: P. J. Linstrom, W. G. Mallard (Eds.): NIST Chemistry WebBook, NIST Standard Reference Database Number 69 . National Institute of Standards and Technology , Gaithersburg MD, accessed May 2, 2013.

[Sigma-1] ↑ ^a ^b ^c ^d ^e ^f data sheet 3,5-Dinitrobenzoic acid, 99% from Sigma-Aldrich , accessed on March 7, 2017 ( PDF ).

[acros-2] ta sheet 3,5-Dinitrobenzoic acid, 99% from Acros, accessed December 25, 2013.

[CRC-3] CRC Handbook of Tables for Organic Compound Identification , Third Edition, 1984, ISBN 0-8493-0303-6 , p. 206.

[Saunders_1942-4] B. C. Saunders, GJ Stacey, IGE Wilding: The Preparation of 3: 5-Dinitrobenzoic Acid and 3: 5-Dinitrobenzoyl Chloride - Observations on the Acylation of Amino-acids by means of 3: 5-Dinitrobenzoyl Chloride and certain other Acid Chlorides ; in: Biochem. J. , 1942 , 36 (3-4), pp. 368-375, PMID 16747534 ; PMC 1265703 (free full text).

[5] RQ Brewster, Bill Williams, Ross Phillips: 3,5-Dinitrobenzoic Acid In: Organic Syntheses . 22, 1942, p. 48, doi : 10.15227 / orgsyn.022.0048 ; Coll. Vol. 3, 1955, p. 337 ( PDF ).

[6] BA Lebedev, V. Yu. Dolmatov, PS Zubarev, NV Latynov, MM Aleksandrov, RI Ponamareva: Preparation of 3,5-dinitrobenzoic acid from meta-nitrobenzoic acid ; in: Pharmaceutical Chemistry Journal , 1988 , 22 (5), pp. 399-401, doi : 10.1007 / BF00769656 .