Dibromobenzenes

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Dibromobenzenes
Surname 1,2-dibromobenzene 1,3-dibromobenzene 1,4-dibromobenzene
other names o -dibromobenzene m -dibromobenzene p -dibromobenzene
Structural formula Structure of 1,2-dibromobenzene Structure of 1,3-dibromobenzene Structure of 1,4-dibromobenzene
CAS number 583-53-9 108-36-1 106-37-6
PubChem 11414 7927 7804
Molecular formula C 6 H 4 Br 2
Molar mass 235.92 g mol −1
Physical state liquid firmly
Melting point 4-6 ° C −7 ° C 83-87 ° C
boiling point 224 ° C 218-219 ° C 219 ° C
GHS
labeling
07 - Warning
Caution
07 - Warning
Caution
07 - Warning 09 - Dangerous for the environment
Caution
H and P phrases 315-319-335 315-319-335 315-319-335-400
no EUH phrases no EUH phrases no EUH phrases
261-305 + 351 + 338 261-305 + 351 + 338 261-273-305 + 351 + 338

In chemistry, the dibromobenzenes form a group of substances consisting of a benzene ring with two bromine atoms  (–Br) as substituents . Their different arrangements ( ortho , meta or para ) result in three constitutional isomers with the empirical formula C 6 H 4 Br 2 .

properties

The boiling points of the three isomers are practically the same, while their melting points differ more clearly. 1,4-Dibromobenzene, which has the highest symmetry, has the highest melting point.

presentation

Renewed bromination ( second substitution ) of bromobenzene with bromine and iron (III) bromide results in mixtures of the three isomers, with the meta derivative only being obtained in small quantities. The ortho / meta / para ratio is 13% / 2% / 85%. The dibromobenzenes can be prepared from the phenylenediamines by diazotizing both amino groups and then adding copper (I) bromide ( Sandmeyer reaction ).

Individual evidence

  1. ↑ a b c data sheet 1,2-dibromobenzene from Sigma-Aldrich , accessed on March 13, 2017 ( PDF ).
  2. ↑ a b c data sheet 1,3-dibromobenzene from Sigma-Aldrich , accessed on March 13, 2017 ( PDF ).
  3. ↑ a b c data sheet 1,4-dibromobenzene from Sigma-Aldrich , accessed on March 13, 2017 ( PDF ).
  4. ^ K. Peter C. Vollhardt , Neil E. Schore: Organische Chemie , 4th edition, Wiley-VCH, Weinheim 2005, ISBN 978-3-527-31380-8 , p. 824.
  5. ^ K. Peter C. Vollhardt , Neil E. Schore: Organische Chemie , 4th edition, Wiley-VCH, Weinheim 2005, ISBN 978-3-527-31380-8 , p. 1194.