Nitrobenzaldehydes

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Nitrobenzaldehydes
Surname 2-nitrobenzaldehyde 3-nitrobenzaldehyde 4-nitrobenzaldehyde
other names o -nitrobenzaldehyde m -nitrobenzaldehyde p -nitrobenzaldehyde
Structural formula Structure of 2-nitrobenzaldehyde Structure of 3-nitrobenzaldehyde Structure of 4-nitrobenzaldehyde
CAS number 552-89-6 99-61-6 555-16-8
PubChem 11101 7449 541
Molecular formula C 7 H 5 NO 3
Molar mass 151.12 g mol −1
Physical state firmly
Brief description slightly yellow crystalline powder
Melting point 41-43 ° C 55 ° C 103-106 ° C
boiling point 156 ° C (20 hPa) 164 ° C (31 hPa) -
GHS
labeling
07 - Warning
Caution
07 - Warning
Caution
07 - Warning
Caution
H and P phrases 302-315-319-335 302-411 317-319-412
no EUH phrases no EUH phrases no EUH phrases
261-305 + 351 + 338 273 261-280-302 + 352
305 + 351 + 338

In chemistry, nitrobenzaldehydes form a group of substances that are derived from both benzaldehyde and nitrobenzene . The structure consists of a benzene ring with attached aldehyde  (-CHO) and nitro group  (-NO 2 ). Their different arrangement ( ortho , meta or para ) results in three constitutional isomers with the empirical formula C 7 H 5 NO 3 .

presentation

Preparation of 2-nitrobenzaldehyde
  • 3-Nitrobenzaldehyde is obtained from benzaldehyde by reaction with fuming nitric acid in the presence of concentrated sulfuric acid .
Preparation of 3-nitrobenzaldehyde
Preparation of 4-nitrobenzaldehyde

properties

The nitrobenzaldehydes are slightly yellow crystalline solids, some of which have a bitter almond odor. The 4-nitrobenzaldehyde, which has the highest symmetry, has the highest melting point.

In a basic medium, the nitrobenzaldehydes disproportionate in a Cannizzaro reaction to form nitrobenzoic acids and nitrobenzyl alcohols .

use

  • 2-Nitrobenzaldehyde reacts with acetone to form indigo .
Reaction equation for the production of indigo.

Individual evidence

  1. a b c Entry on 2-nitrobenzaldehyde in the GESTIS substance database of the IFA , accessed on March 29, 2016(JavaScript required) .
  2. a b c Entry on 3-nitrobenzaldehyde in the GESTIS substance database of the IFA , accessed on March 29, 2016(JavaScript required) .
  3. a b c Entry on 4-nitrobenzaldehyde in the GESTIS substance database of the IFA , accessed on March 29, 2016(JavaScript required) .
  4. Test specification : Nitration of benzaldehyde to 3-nitrobenzaldehyde (PDF) from the collection of integrated organic-chemical internship at the University of Regensburg, accessed on October 30, 2011.
  5. University of Hamburg: 3-nitrobenzaldehyde, test instructions (PDF; 24 kB).
  6. ^ SV Lieberman and Ralph Connor: p-Nitrobenzaldehyde In: Organic Syntheses . 18, 1938, p. 61, doi : 10.15227 / orgsyn.018.0061 ; Coll. Vol. 2, 1943, p. 441 ( PDF ).
  7. Helmut Schmidt: "Indigo - 100 Years of Industrial Synthesis", in: Chemie in our Time , 1997 , 31  (3), pp. 121–128; doi: 10.1002 / ciuz.19970310304 .

See also