Arsabenzene
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| General | |||||||||||||
| Surname | Arsabenzene | ||||||||||||
| other names |
Arsinine |
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| Molecular formula | C 5 H 5 As | ||||||||||||
| Brief description |
air sensitive liquid |
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| Molar mass | 140.02 g mol −1 | ||||||||||||
| Physical state |
liquid |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | |||||||||||||
Arsabenzene is an aromatic heterocycle that contains an arsenic atom in addition to carbon and hydrogen . The molecular formula is C 5 H 5 As. It is therefore a heavier homologue of pyridine and phosphabenzene and is one of the heterobenzenes with the general formula C 5 H 5 E (E = N, P, As, Sb, Bi).
structure
Arsabenzene is planar. The C – C bond distance is 139 pm, the As – C bond distance 185 pm. This is 6.6% shorter compared to a “normal” As – C single bond.
presentation
The first synthesis of a substituted arsaabenzene - more precisely 9-arsaanthracene - was described by Peter Jutzi and Friedrich Bickelhaupt .
A synthesis for arsaabenzene has been described starting from arsenic trichloride :
- CH 2 (CHCH) 2 SnBu 2 + AsCl 3 → CH 2 (CHCH) 2 AsCl + Bu 2 SnCl 2
- CH 2 (CHCH) 2 AsCl → C 5 H 5 As + HCl
Properties and reactions
Arsabenzene is sensitive to air and has an onion-like odor. It decomposes when heated.
Arsabenzene can be substituted electrophilically in the ortho - and para -position. B. Friedel-Crafts acylation possible.
Comparison with other heterobenzenes
All heterobenzenes have in common their aromaticity. The stability decreases with the atomic number of the heteroatom . The bond lengths and angles of the heterobenzenes of the 15th group of the periodic table are shown below (from left to right: pyridine, phosphabenzene, arsabenzene, stibabenzene and bismabenzene ):
The stability, which decreases with increasing atomic number, is related to the fact that a [4 + 2] cycloaddition preferably already takes place at low temperatures and the isolation of the pure substances consequently z. T. is impossible.
Arsabenzene is less basic than pyridine and unreactive towards Lewis acids . Trifluoroacetic acid does not protonate arsabenzene.
In 1982 Gottfried Märkl provided a compilation of the properties, syntheses and reactions of the pyridine homologues phosphabenzene and arsabenzene .
Individual evidence
- ↑ a b c J. IG Cadogan, J. Buckingham, F. Macdonald: Dictionary of Organic Compounds , 6th. Edition, Volume 10, CRC Press, 1997, ISBN 0-412-54110-6 , p. 491.
- ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
- ↑ a b c d C. Elschenbroich: Organometallics ( German ). Wiley-VCH Weinheim, 2006, ISBN 3-527-29390-6 , pp. 229-230.
- ↑ a b A. J. Ashe: The Group 5 Heterobenzenes . In: Accounts of Chemical Research . 11, No. 4, 1978, pp. 153-157. doi : 10.1021 / ar50124a005 .
- ↑ Christoph Elschenbroich: Organometallchemie . 6th edition. Teubner Verlag, Wiesbaden 2008 ( limited preview in the Google book search [accessed on February 25, 2010]).
- ↑ Gottfried Märkl: Phosphabenzol and Arsabenzol. The higher element homologues of pyridine , Chemie in our time 16 (1982) 139-148, doi : 10.1002 / ciuz.19820160503 .