Triphenylboroxine
Structural formula | ||||||||||||||||
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General | ||||||||||||||||
Surname | Triphenylboroxine | |||||||||||||||
other names |
Triphenylboroxol |
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Molecular formula | C 18 H 15 B 3 O 3 | |||||||||||||||
Brief description |
colorless crystals |
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External identifiers / databases | ||||||||||||||||
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properties | ||||||||||||||||
Molar mass | 311.748 g mol −1 | |||||||||||||||
Physical state |
firmly |
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Melting point |
218-220 ° C |
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solubility |
almost insoluble in water |
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safety instructions | ||||||||||||||||
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As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . |
Triphenylboroxine is an organic boron compound that can be assigned to the boroxine group . The compound is also the trimeric anhydrate of phenylboronic acid .
Extraction and presentation
The compound can be obtained from phenylboronic acid with elimination of water by dry heating.
The formation of boroxine is slightly exothermic with a heat of reaction of −14.3 kJ mol −1 .
Another production variant is the conversion of boron trioxide with triphenylborane in tetrachloromethane .
properties
Physical Properties
Triphenylboroxine crystallizes in a monoclinic crystal lattice in the space group P 2 1 / c (space group no. 14) . The B 3 O 3 ring and the three substituted phenyl rings form an almost planar molecule with a slight curvature, since a boron atom in the B 3 O 3 ring deviates about 0.119 Å from the plane of the ring.
Chemical properties
The compound hydrolyzes immediately to phenylboronic acid in water. The hydrolysis is an equilibrium reaction with
The equilibrium constant results from
The equilibrium constant at 25 ° CK = 0.32 mol·l −1 .
Triphenylboroxine forms stable donor-acceptor adducts with nitrogen bases such as amines , hydrazines and nitrogen heterocycles . The adduct formation is based on donor-acceptor bonds between the boron atoms as electrophilic electron pair acceptors and the nitrogen atoms as nucleophilic electron pair donors . The structure of some adducts was characterized by means of X-ray structure analysis and 1 H or 11 B NMR spectroscopy .
Donor | composition | Melting point | source |
Propylamine | 1: 1 | 140-143 ° C | |
Diethylamine | 1: 1 | 85 ° C | |
Piperidine | 1: 1 | 213 ° C | |
Trimethylamine | 1: 1 | ||
Triethylamine | 1: 1 | 39 ° C | |
Quinuclidine | 1: 1 | ||
DABCO | 1: 1 | ||
Urotropin | 1: 2 | ||
Morpholine | 1: 1 | 188-189 ° C | |
p-phenylenediamine | 3: 2 | 167-168 ° C | |
Hydrazine | 1: 1 | 95-97 ° C | |
Hydrazine | 2: 1 | 48-52 ° C | |
1,2-dimethylhydrazine | 1: 1 | 102-105 ° C | |
1,1-dimethylhydrazine | 1: 1 | 44-48 ° C | |
1,1-dimethylhydrazine | 2: 1 | 107-109 ° C | |
Pyridine | 1: 1 | 152 ° C | |
3,5-lutidine | 1: 1 | ||
2,4-lutidine | 1: 1 | ||
2,6-lutidine | 1: 1 | ||
Quinoxaline | 1: 1 | ||
3,6-diaminoacridine | 1: 2 | 252-255 ° C |
The compound decomposes at higher temperatures. The decomposition temperature given with the criterion of a decomposition rate of 1 mol% h −1 is 357 ° C.
use
The compound can act as a flame retardant additive in polymers. In organic synthesis it can be used as an alternative to boronic acids in Miyaura-Suzuki couplings or couplings catalyzed by rhodium.
Individual evidence
- ↑ Entry on 2,4,6-triphenylboroxine at TCI Europe, accessed on April 29, 2014.
- ↑ a b c data sheet 2,4,6-TRIPHENYLBOROXIN, Aldrich at Sigma-Aldrich , accessed on April 29, 2014 ( PDF ).
- ↑ Sporzynski, A .; Szatylowicz, H .: Can triorganoboroxins exist in a “monomeric” RBO form? MNDO calculations and ebulliometric molecular weight determination in J. Organomet. Chem. 470 (1994) 31-34, doi : 10.1016 / 0022-328X (94) 80145-2 .
- ↑ a b Michaelis, A .; Becker, P .: About monophenylboron chloride and some derivatives of the same in Chem. Ber. 15 (1882) 180-185, doi : 10.1002 / cber.18820150143 .
- ↑ a b Washburn, RM; Levens, E .; Albright, CF; Cheap, FA: Benzeneboronic Anhydrides In: Organic Syntheses . 39, 1959, p. 3, doi : 10.15227 / orgsyn.039.0003 ; Coll. Vol. 4, 1963, p. 68 ( PDF ).
- ↑ a b c Tokunaga, Y .; Ueno, H .; Shimomura, Y .; Seo, T .: Formation of Boroxine: Its Stability and Thermodynamic Parameters in Solution in Heterocycles 57 (2002) 787-790, doi : 10.3987 / COM-02-9464 .
- ↑ Hennion, GF; McCusker, PA; Ashby, EC; Rutkowski, AJ: Organoboron Compounds. VIII. The Reaction of Triorganoboranes with Boric Oxide in J. Am. Chem. Soc. 79 (1957) 5194-5196, doi : 10.1021 / ja01576a032 .
- ↑ a b Brock, CP; Minton, RP; Niedenzu, K .: Structure and Thermal Motion of Triphenylboroxin in Acta Cryst. C43 (1987) 1775-1779, doi : 10.1107 / S010827018709022X .
- ↑ a b c d e Yabroff, DL; Branch, GEK: Addition Compounds of Phenylboric Acid with Bases in J. Am. Chem. Soc. 55 (1933) 1663-1665, doi : 10.1021 / ja01331a057 .
- ↑ a b c d e f g h i j k l Yalpani, M .; Boese, R .: The structure of amine adducts of Triorganylboroxines in Chem. Ber. 116 (1983) 3347-3358, doi : 10.1002 / cber.19831161011 .
- ↑ a b Fieldner, WL; Chamberlain, MM; Brown, CA: Formation of an adduct of triphenylboroxine and p-phenylenediamine in J. Org. Chem. 26 (1961) 2154-2155, doi : 10.1021 / jo01065a637 .
- ↑ a b c d e f Das, MK; Mariategui, JF; Niedenzu, K .: Boron-nitrogen compounds. 114. Hydrazine complexes of B-triorganoboroxins in Inorg. Chem. 26 (1987) 3114-3116, doi : 10.1021 / ic00266a011 .
- ↑ a b c d Snyder, H .; Konecky, M .; Lennarz, W .: Aryl Boronic Acids. II. Aryl Boronic Anhydrides and their Amine Complexes in J. Am. Chem. Soc. 80 (1958) 3611-3615, doi : 10.1021 / ja01547a033 .
- ↑ Beckmann, J .; Dakternieks, D .; Duthie, A .; Lim, AEK; Tiekink, ERT; Tiekink, ERT: Ring strain in boroxine rings: computational and experimental considerations in J. Organomet. Chem. 633 (2001) 149-156, doi : 10.1016 / S0022-328X (01) 01060-9 .
- ↑ Johns, IB; McElhill, EA; Smith, JO: Thermal Stability of Some Organic Compounds in J. Chem. Eng. Data 7 (1962) 277-281, doi : 10.1021 / je60013a036 .
- ↑ Morgan, AB; Jurs, JL; Tour, JM: in Polym. Prep. 40 (1999) 553.
- ↑ Miyaura, N .; Suzuki, A .: Palladium-Catalyzed Cross-Coupling Reactions of Organoboron Compounds in Chem. Rev. 95 (1995) 2457-2483, doi : 10.1021 / cr00039a007 .
- ↑ Hayashi, T .; Inoue, N .; Taniguchi, N .; Ogasawara, M .: Rhodium-Catalyzed Hydroarylation of Alkynes with Arylboronic Acids: 1,4-Shift of Rhodium from 2-Aryl-1-alkenylrhodium to 2-Alkenylarylrhodium Intermediate in J. Am. Chem. Soc. 123 (2001) 9918-9919, doi : 10.1021 / ja0165234 .