Boron halogenides

Finally, an important form of boron nitride should be mentioned, pyrolytic boron nitride. It is manufactured by reacting ammonia and a boron halogenide at about 2000°C and depositing the BN vapor on a graphite substrate or mandrel. The characteristic feature of pyrolytic boron nitride is the high degree of crystal orientation with the hexagonal basal plane parallel to the mold surface and the c-direction perpendicular to the substrate. 

BertheviUe B, Herrmannsdorfer T, Yvon K (2001) Structure data for K2MgH4 and Rb2CaH4 and comparison with hydride and fluoride analogues. J Alloys Compd 325 L13-L16 Hines J, Cambon O, Astier R et al (2004) Crystal structures of a-quartz homeotypes boron phosphate and boron arsenate structure-property relationships. Z Krist 219 32-37 Feldmann C, Jansen M (1995) Zurkristallchemischen Ahnlichkeit von Aurid- und Halogenid-lonen. Z anorg allgem Chem 621 1907-1912... 

In another one-pot procedure, a Suzuki coupling and a Wittig olefination were realized back to back. A great variety of aryl- and heteroaryl halogenides and aldehyde-functionalized aryl- and heteroaryl-boronic acids were used along with ethoxycarbonylmethylenephosphorane (Scheme 95/1). In another variation, 2-bro-mothiophene, (4-formylphenyl)boronic acid and three different phosphoranes were used (Scheme The biaryl/biheteroaryl/arylheteroaryl acrylic or other... 

Alkylation describes the reaction where an active hydrogen is replaced with an alkyl group, for example, a methyl group. Most polar groups can be alkylated, and many reagents can be used, for example, alkyl halogenides, diazo alkanes, and N,N -dimethylformamide dialkyl acetal. An example of an alkylation is the formation of methyl esters of fatty acids by using methanolic BF3, where boron trifluoride (BF3) acts as a catalyst. 

The inductively coupled plasma mass spectrometry (ICP-MS) measurement confirmed the absence of copper in both the products obtained with halogenides and with the boronic acids. The catalyst was recovered and dried after washing with ethanol followed by acetone before reuse. This was recycled up to eight runs with a marginal linear loss of activity of the catalyst due to some loss during handling in each step. 

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