Boron insertion

O BH SiMe ° /y-H Scheme 3.3-4. Boron insertion into the siladecaborane skeleton. 

LOCA (secondary) - increased water inventory increases time constants - automatic and passive (degree C) boron insertion and core coolant supply - not important... 

BODIPY has a rigid structure, which can be formed by boron insertion with BF3 OEt2 into a dipyrromethene unit. Generally, the synthesis of BODIPY derivatives starts from the dipyrromethene precursor. It is relatively easy to construct the precursor using the well-known pyrrole condensation reaction. There are two common synthetic strategies, especially for symmetric and unsymmetric BODIPY cores, respeetively. 

In contrast, asymmetric BODIPY dyes are usually obtained by a two-step procedure via condensation of a ketopyrrole with a pyrrole fragment that is not substituted at the 2-position, followed by boron insertion with BF3-OEt2 (Scheme 7.2). 

Roscoe, J. S., Kongpricha, S., and Papetti, S. 1970. Icosahedral carboranes. XIV. Preparation of boron-substituted carboranes by boron-insertion reactions. Inorg. Chem., 9, 1561-3. 

The 4-pyridylboronic acid and the 3-pyridylboronic acids led to dimeric cobaloximes 161 and 162 by a reaction with cobaloxime compounds. The bridges consisted in the axial pyridyl fragment and the boron inserted inside the dioxime macrocycles. In the case of 3-aminophenylboronic acid, a trinuclear arrangement 163 was observed (Scheme 23). ... 

Single-Carbon Insertion Reactions. Carbonylation, cyanidation, and "DCME," and related reactions are convenient general processes developed to bring about the transfer of organic groups from boron to a siagle-carbon atom. 

Boron haUdes have also been shown to insert into B—B bonds to give initial products with the new boryl moiety in a bridge position (80). 

Control of the nuclear chain reaction in a reactor is maintained by the insertion of rods containing neutron absorbing materials such as boron, boron carbide, or borated steel. In state-of-the-art high temperature reactor designs, such as the Gas... 

A valuable extension of the diazomethane reaction for the preparation of A-homosteroids was discovered by Johnson, Neeman and Birkeland " who found that a,j5-unsaturated ketones are homologated by reaction with diazomethane in the presence of either fluoroboric acid or boron trifluoride. The main product is formed by the insertion of a methylene group between the carbonyl group and the unsaturated a-carbon to give a / ,y-unsaturated ketone. 

Ceramic-coated disposable inserts, including silicon nitride, boron nitride, titanium nitride (TIN), titanium carbide (TIC) and sintered synthetic diamond ... 

Although these methods were applied for the synthesis of a number of various phthalocyanines with different central atoms (e.g., H2, Cu, Zn, Ni, Pt, Pd, Lu, etc.) not all metal phthalocyanines can be prepared by one of these methods. For example, the synthesis of silicon phthalocyanine, rhenium phthalocyanine and boron subphthalocyanine need more drastic conditions. In the following, an overview of the synthesis of phthalocyanines containing all central metals which have hitherto been inserted into the ring is given. 

If the rate of the chain reaction exceeds a certain level, the reactor will become too hot and begin to melt. Control rods—rods made from neutron-absorbing elements, such as boron or cadmium, and inserted between the fuel rods—help to control the number of available neutrons and the rate of nuclear reaction. 

The structure of CaB contains bonding bands typical of the boron sublattice and capable of accommodating 20 electrons per CaB formula, and separated from antibonding bands by a relatively narrow gap (from 1.5 to 4.4 eV) . The B atoms of the B(, octahedron yield only 18 electrons thus a transfer of two electrons from the metal to the boron sublattice is necessary to stabilize the crystalline framework. The semiconducting properties of M B phases (M = Ca, Sr ", Ba, Eu, Yb ) and the metallic ones of M B or M B5 phases (Y, La, Ce, Pr, Nd ", Gd , Tb , Dy and Th ) are directly explained by this model . The validity of these models may be questionable because of the existence and stability of Na,Ba, Bft solid solutions and of KB, since they prove that the CaB -type structure is still stable when the electron contribution of the inserted atom is less than two . A detailed description of physical properties of hexaborides involves not only the bonding and antibonding B bands, but also bonds originating in the atomic orbitals of the inserted metal . ... 

This reaction typifies the two possibilities of reaction routes for M-catalyzed addition of an S-X (or Se-X) bond to alkyne (a) oxidative addition of the S-X bond to M(0) to form 94, (b) insertion of alkyne into either the M-S or M-X bond to provide 95 or 96 (c) C-X or C-S bond-forming reductive elimination to give 97 (Scheme 7-21). Comparable reaction sequences are also discussed when the Chalk-Harrod mechanism is compared with the modified Chalk-Harrod mechanism in hydrosily-lations [1,3]. The palladium-catalyzed thioboratiori, that is, addition of an S-B bond to an alkyne was reported by Miyaura and Suzuki et al. to furnish the cis-adducts 98 with the sulfur bound to the internal carbon and the boron center to the terminal carbon (Eq. 7.61) [62]. 

The boranediyl insertion with BC13 and BBr3 gives products with 1-haloboratabenzene ligands which easily undergo nucleophilic substitution at boron complex 6 has been made in this way (57,79). However, these reactions have never been published in detail. 

More often, nucleophilic addition at boron can only be observed spectroscopically and is followed by more or less fast boranediyl extrusion (see Section VI,A) (69). A speculative mechanism has been proposed which links this boranediyl extrusion with the boranediyl insertion described earlier (Section V,A) (2,69). 

Boron-containing carbons synthesized by co-pyrolysis of coal-tar pitch with pyridine-borane complex (series 25Bn) have already been considered as hosts for lithium insertion [4], Unlike the commercial graphites described above, the boron-doped carbon 25B2 (WUT) as received was not suitable for direct use in the cylindrical cell due to very large and hard particles. This feature makes the coating process very difficult. 

Fig. 7 A zirconium rotor (A), and several types of caps (B) Kel-F, (C) boron nitride, and the stator (D) in which the doubly tuned transmitter/receiver coil (E) is inserted. Here, the rotor is 22 mm in length and 7 mm in outer diameter.

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