3,5-dinitrobenzoic acid
Structural formula | ||||||||||||||||
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General | ||||||||||||||||
Surname | 3,5-dinitrobenzoic acid | |||||||||||||||
Molecular formula | C 7 H 4 N 2 O 6 | |||||||||||||||
Brief description |
light yellow crystalline powder |
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properties | ||||||||||||||||
Molar mass | 212.12 g mol −1 | |||||||||||||||
Physical state |
firmly |
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density |
1.683 g cm −3 |
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Melting point |
204-206 ° C |
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pK s value |
2.82 (25 ° C) |
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solubility |
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safety instructions | ||||||||||||||||
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Toxicological data | ||||||||||||||||
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.
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.