Triphenylboroxine

Structural formula
General
Surname	Triphenylboroxine
other names	Triphenylboroxol
Molecular formula	C 18 H 15 B 3 O 3
Brief description	colorless crystals
External identifiers / databases
EC number	621-783-0
ECHA InfoCard	100.150.604
PubChem	72595
Wikidata	Q16857560
properties
Molar mass	311.748 g mol −1
Physical state	firmly
Melting point	218-220 ° C
solubility	almost insoluble in water
safety instructions
GHS labeling of hazardous substances	no GHS pictograms
	no GHS pictograms
H and P phrases	H: 413
	P: no P-phrases
	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. Template: room group / 14

Chemical properties

The compound hydrolyzes immediately to phenylboronic acid in water. The hydrolysis is an equilibrium reaction with

${\ displaystyle \ mathrm {3PhB (OH) _ {3} \ \ rightleftharpoons \ Boroxin + 3H_ {2} O}}$

The equilibrium constant results from

{\ displaystyle K = {c (Boroxine) * c ^ {3} (H_ {2} O) \ over c ^ {3} (PhB (OH) _ {2})}}

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-acceptor adducts between triphenylboroxine and nitrogen bases
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 .

[TCI-1] Entry on 2,4,6-triphenylboroxine at TCI Europe, accessed on April 29, 2014.

[Sigma-2] ta sheet 2,4,6-TRIPHENYLBOROXIN, Aldrich at Sigma-Aldrich , accessed on April 29, 2014 ( PDF ).

[Sporzynski-3] 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 .

[Michaelis-4] 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 .

[Washburn-5] 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 ).

[Tokunaga-6] 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 .

[7] 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 .

[Brock-8] Brock, CP; Minton, RP; Niedenzu, K .: Structure and Thermal Motion of Triphenylboroxin in Acta Cryst. C43 (1987) 1775-1779, doi : 10.1107 / S010827018709022X .

[Yabroff-9] Yabroff, DL; Branch, GEK: Addition Compounds of Phenylboric Acid with Bases in J. Am. Chem. Soc. 55 (1933) 1663-1665, doi : 10.1021 / ja01331a057 .

[Yalpani-10] ↑ ^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 .

[Fieldner-11] 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 .

[Das-12] ↑ ^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 .

[Snyder-13] 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-14] 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 .

[15] 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 .

[16] Morgan, AB; Jurs, JL; Tour, JM: in Polym. Prep. 40 (1999) 553.

[17] Miyaura, N .; Suzuki, A .: Palladium-Catalyzed Cross-Coupling Reactions of Organoboron Compounds in Chem. Rev. 95 (1995) 2457-2483, doi : 10.1021 / cr00039a007 .

[18] 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 .