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An efficient one-pot method for synthesis of simple alkyltrifluoroborate salts has been developed. Alkyldichloroboranes, prepared by the Matteson Hydroboration Method using in situ generated HBCl2, were esterified with 2-propanol, treated with aqueous KHF2 and isolated using standard procedures. The overall isolated yields were generally greater than 90% when fluoridation was conducted under nitrogen. In contrast, reactions using “open air” conditions showed oxidation and gave lower yields of the alkyltrifluoroborate salts.

Mixed organoboranes based on diphenyl- or dimethylalkylboranes transfer the alkyl group in the reductive alkylation of p-benzoquinone to form the alkylhydroquinones in very high yields. The auxiliary groups do not transfer or have a low migratory aptitude. Primary and secondary alkyl groups are transferred with retention of regio- and stereochemistry to the hydroquinone. O-Alkylation is the major product with tertiary and secondary groups with steric bulk in proximity to the site of attachment. The presence of metal salts, such as magnesium, results in reduction to the unsubstituted hydroquinone. This reaction makes the first practical route to alkylhydroquinones via organoboranes.

The reaction of styrene and “Cp 2 Zr” forms the trans-2,5-diphenylzirconacycle. Transmetalation of this zirconacyle with an equivalent of boron trichloride forms the 1-chloro-trans-2,5-diphenylborolane with retention of stereochemistry. This B-chloroborolane is converted into other boranes and can be oxidized to the diol.

The hydrozirconation of alkenes or alkynes yields the dicyclopentadienyl alkyl- or alkenylzirconium chloride, respectively, in high yields and with high regioselectivity. The reaction of these organozirconium compounds with a boron halide results in the exchange of the halogen and organic group, forming the organoborane. We report here a systematic investigation of the transmetallation of organic groups from zirconium to a variety of boron compounds. The migration is facile to a variety of boron halides, yielding structurally different types of alkyl or alkenylboranes in good to high yields. Exploiting the unique reactivity and selectivity of the hydrozirconation reaction for the preparation of organoboranes expands the range of potential of both metals for synthesis.

The reaction of the anhydrides of boronic or borinic acids with trihaloboranes in hydrocarbon solvents leads to the clean exchange of the oxygen and halide to form the organodihaloboranes and diorganohaloboranes in good to excellent yields.

The hydrozirconations of acyclic alkenes are known to yield the dicyclopentadienyl-1-aklyl-zirconium chlorides regioselectively and in high yields. These alkyl groups may readily be transmetallated to the haloboranes forming regioisomeric pure alkylboranes in good yields. In principle, this migration reaction combines the facile hydrozirconation and unique isomerization reactions of organozirconiums with the established chemistry of boron, expanding the utility of both metals for use in organic synthesis.

The hydrozirconation of alkenes or alkynes yields the dicyclopentadienyl alkyl- or alkenylzirconium chloride, respectively, in high yields and with high regioselectivity. The reaction of these organozirconium compounds with a boron halide results in the exchange of the halogen and organic group, forming the organoborane. We report here a systematic investigation of the transmetallation of organic groups from zirconium to a variety of boron compounds. The migration is facile to a variety of boron halides, yielding structurally different types of alkyl or alkenylboranes in good to high yields. Exploiting the unique reactivity and selectivity of the hydrozirconation reaction for the preparation of organoboranes expands the range of potential of both metals for synthesis.

The reaction of styrene and “Cp 2 Zr” forms the trans-2,5-diphenylzirconacycle. Transmetalation of this zirconacyle with an equivalent of boron trichloride forms the 1-chloro-trans-2,5-diphenylborolane with retention of stereochemistry. This B-chloroborolane is converted into other boranes and can be oxidized to the diol.

The hydrozirconations of acyclic alkenes are known to yield the dicyclopentadienyl-1-aklyl-zirconium chlorides regioselectively and in high yields. These alkyl groups may readily be transmetallated to the haloboranes forming regioisomeric pure alkylboranes in good yields. In principle, this migration reaction combines the facile hydrozirconation and unique isomerization reactions of organozirconiums with the established chemistry of boron, expanding the utility of both metals for use in organic synthesis.

The reaction of the anhydrides of boronic or borinic acids with trihaloboranes in hydrocarbon solvents leads to the clean exchange of the oxygen and halide to form the organodihaloboranes and diorganohaloboranes in good to excellent yields.

Methylborane (MeBH 2 ), the simplest of the monoalkylboranes, possesses extraordinary hydroborating characteristics in tetrahydrofuran. In this solvent MeBH 2 selectively hydroborates all important classes of alkenes, hindered and nonhindered, to yield the methylalkylborane MeRBH. These dialkylboranes are readily converted into and isolated as their borinic esters, MeRBOR', which in turn can be transformed into methyl ketones, thus providing a simple and highly regio- and stereoselective synthesis of the latter. The addition of a second equivalent of another alkene to the methyalkylborane gives a sequential hydroboration product, MeR A R B B. This mixed trialkylborane is readily converted into the corresponding tertiary alcohol via carbonylation-oxidation

Trialkoxyboranes are conveniently synthesized in good to excellent yields from the corresponding alcohols or phenols and boric acid using calcium hydride as a drying agent. This method is successful for a variety of sterically hindered alcohols. In a new general route, trialkoxyboroxins are formed under mild reaction conditions from these same readily available materials. The trialkoxyboranes and trialkoxyboroxins can be interconverted by addition of stoichiometric amounts of boric acid or the alcohols/phenols, in the presence of calcium hydride. Calcium hydride is most effective for the removal of water. This allows for a simple and convenient route for the preparation of the useful trialkoxyboranes and the previously inaccessible trialkoxyboroxins, for further investigation or applications.

C 2 -symmetric bis(sulfonamide) ligands derived from trans -(1 R ,2 R )-cyclohexane-1,2-diamine were synthesized and complexed with [Cp ∗ RhCl 2 ] 2 in situ and used in the ATH of aromatic ketones with aqueous sodium formate as the hydrogen source. The chiral secondary alcohols were obtained with 90–99% enantioselectivity and in 50–100% yield. Reductions in water were faster than those in isopropanol/KOH.

New chiral Schiff base ligands derived from tert -butyl salicylaldehydes bearing electron withdrawing and donating groups were synthesized by reaction with various substituted chiral amino alcohols. These ligands were used with titanium tetraisopropoxide to study steric and electronic effects on the enantioselectivity of the trimethylsilylcyanation of benzaldehyde. ZINDO calculations are in agreement with the experimental results on the intermediate complexes, which indicate that the steric effects of the substituents are more important than the electronic ones.

Trialkoxyboranes are conveniently synthesized in good to excellent yields from the corresponding alcohols or phenols and boric acid using calcium hydride as a drying agent. This method is successful for a variety of sterically hindered alcohols. In a new general route, trialkoxyboroxins are formed under mild reaction conditions from these same readily available materials. The trialkoxyboranes and trialkoxyboroxins can be interconverted by addition of stoichiometric amounts of boric acid or the alcohols/phenols, in the presence of calcium hydride. Calcium hydride is most effective for the removal of water. This allows for a simple and convenient route for the preparation of the useful trialkoxyboranes and the previously inaccessible trialkoxyboroxins, for further investigation or applications.

Methylborane, MeBH 2 , the simplest of the monoalkylboranes, possesses extraordinary hydroboration characteristics in tetrahydrofuran. In this solvent, methylborane is capable of monohydroborating the usual classes of alkenes, hindered and unhindered, to provide the simple alkylmethylboranes, RMeBH. The addition of a second equivalent of another alkene to the alkylmethylborane formed initially produces the sequential hydroboration product, RR′MeB. In all cases there is no evidence of redistributed products.

Methylboronic acid and ita anhydride, tximethylboroxin, were prepared by three routes. The carbonylation of borane-dimethyl sulfide gives in high yields trimethylboroxin, readily hydrated to methylboronic acid. The reaction of methyllithium with selected trialkoxyboranes and methyl Grignards with 2-methoxy1,3,2-&0xaborinane yields the corresponding esters, readily hydrolyzed to methylboronic acid in good yields. Methylboronic acid can be dehydrated to trimethylboroxin. Each of these routes was studied in detail to develop efficient, relatively simple routes to both methylboronic acid and trimethylboroxin.

Engineering developments in the field of high-power (1014 and 1015 neutrons/cm2 sec) research reactors are reviewed with emphasis on fuel element technology and the principle of the flux trap. Calculational methods used in designing reactors are discussed. Several examples of two types of advanced research reactor are described: plate-fuel-element tank reactors and pulsed reactors. Present policies with regard to site selection and containment of research reactors are reviewed briefly. The more important nuclear accidents involving research reactors are summarized.

Methylborane, MeBH 2 , the simplest of the monoalkylboranes, possesses extraordinary hydroboration characteristics in tetrahydrofuran. In this solvent, methylborane is capable of monohydroborating the usual classes of alkenes, hindered and unhindered, to provide the simple alkylmethylboranes, RMeBH. The addition of a second equivalent of another alkene to the alkylmethylborane formed initially produces the sequential hydroboration product, RR′MeB. In all cases there is no evidence of redistributed products.

Optically pure borinic esters such as (IV), obtained from optically pure boronic esters, e.g. (I), by a known route, are treated with the ether (V) in the presence of Li tert-butoxide to give, after oxidation, α-chiral ketones such as (VI) of generally very high enantiomeric purity (> 99% e.e.).

A model is developed which describes the effects of weak collisions on the linear kinetic theory of electrostatic density drift instabilities. A dispersion equation valid at all frequencies and wave numbers is derived using the assumptions of a weak, uniform density gradient; a uniform magnetic field; and the BGK collision operator with a modification of the local approximation. The properties of the universal and collisional density drift instabilities at maximum growth rates are examined in detail. The thresholds of the instabilities are examined for an ionospheric model which includes ion-neutral, electron-neutral, and electron-ion collisions, and are compared with the threshold of the lower hybrid density drift instability. It is concluded that the k to the -5th short wavelength density power spectra observed above 280 km in the PLUMEX experiment are due to the effects of the universal density drift instability.

The linear Vlasov stability of a class of electron velocity distributions which model those observed within the earth's bow shock is examined. The study is restricted to electrostatic waves which propagate parallel to the ambient magnetic field B. Two instabilities are identified which are driven by free energy in the direction parallel to B: an ion acoustic wave with real frequency below the ion plasma frequency and an electron acoustic wave with real frequency of several times the ion plasma frequency. The characteristics of the unstable waves are in accord with observations obtained within the bow shock, in particular, with the trend of the observed electrostatic waves to be polarized parallel to the magnetic field. The instabilities identified here may contribute to electron dissipation in collisionless shocks.