Chlorobenzaldehyde

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Chlorobenzaldehyde
Surname 2-chlorobenzaldehyde 3-chlorobenzaldehyde 4-chlorobenzaldehyde
other names o -chlorobenzaldehyde m -chlorobenzaldehyde p -chlorobenzaldehyde
Structural formula Structure of 2-chlorobenzaldehyde Structure of 3-chlorobenzaldehyde Structure of 4-chlorobenzaldehyde
CAS number 89-98-5 587-04-2 104-88-1
PubChem 6996 11477 7726
Molecular formula C 7 H 5 ClO
Molar mass 140.57 g mol −1
Physical state liquid firmly
Melting point 11-14 ° C 16-18 ° C 45-47 ° C
boiling point 212-214 ° C 213-214 ° C 213-214 ° C
GHS
labeling
05 - Corrosive
danger
07 - Warning
Caution
07 - Warning
Caution
H and P phrases 314 315-319-335 302-315-319-335
no EUH phrases no EUH phrases no EUH phrases
280-305 + 351 + 338-310 261-305 + 351 + 338 261-305 + 351 + 338

In chemistry, chlorobenzaldehydes are a group of substances that are derived from both benzaldehyde and chlorobenzene . The structure consists of a benzene ring with attached aldehyde group  (-CHO) and chlorine  (-Cl) as substituents . Their different arrangements ( ortho , meta or para ) result in three constitutional isomers with the empirical formula C 7 H 5 ClO.

presentation

The synthesis of 4-chlorobenzaldehyde can take place starting from 4-chlorotoluene , which is first reacted with phosphorus pentachloride and chlorine under UV radiation. Hydrolysis of the intermediate product obtained in this way, which is doubly chlorinated on the methyl group, with concentrated sulfuric acid leads to 4-chlorobenzaldehyde.

properties

The 4-chlorobenzaldehyde, which has the highest symmetry, has the highest melting point.

use

Chlorobenzaldehydes are used for triphenylmethane dyes and drugs. 4-chlorobenzaldehyde is a basic substance for the synthesis of the pesticides chlorobenzilate , coumachlor , paclobutrazole , triticonazole and uniconazole . Clomazone is obtained from 2-chlorobenzaldehyde .

The 4-chlorobenzaldehyde can also be used to produce 4-fluorobenzaldehyde.

Individual evidence

  1. ↑ a b c d e f Alfa Aesar catalog 2008/09, p. 445.
  2. ↑ Data sheet 2-chlorobenzaldehyde from Sigma-Aldrich , accessed on October 16, 2016 ( PDF ).
  3. ↑ Data sheet 3-Chlorobenzaldehyde from Sigma-Aldrich , accessed on October 16, 2016 ( PDF ).
  4. ↑ Data sheet 4-chlorobenzaldehyde from Sigma-Aldrich , accessed on October 16, 2016 ( PDF ).
  5. ^ WL McEwen: p-Chlorbenzaldehyde In: Organic Syntheses . 12, 1932, p. 12, doi : 10.15227 / orgsyn.012.0012 ; Coll. Vol. 2, 1943, p. 133 ( PDF ).
  6. ↑ Entry on chlorobenzaldehyde. In: Römpp Online . Georg Thieme Verlag, accessed on May 3, 2014.
  7. ↑ Thomas A. Unger: Pesticide Synthesis Handbook . William Andrew, 1996, ISBN 0-8155-1853-6 , pp. 1028 ( limited preview in Google Book search).
  8. ↑ http://www.prepchem.com/synthesis-of-4-fluorobenzaldehyde/