A versatile protocol for the preparation of substituted 1- and 2-naphthyl piperazines from aminonaphthols

Aminonaphthols are easily transformed into a variety of 1- and 2-naphthyl piperazines using a sequence of diazotization, iodide substitution and Pd(0) catalyzed coupling reactions.     

On weak spreadability of distributed-parameter systems and its achievement via linear--quadratic control techniques

In this paper, the concept of weak spreadability is introduced.It constitutes an extension of the idea developed by El Jai& Kassara. In the case of linear distributed systems weconsider quadratic control techniques with a conveniently penalizedcriterion which makes the system weakly spreadable. The approachis outlined for a convection—diffusion system, and theresults of a numerical study are also included to illustratethe main features of the considered problem.     

Rail vs truck transport of biomass

This study analyzes the economics of transshipping biomass from truck to train in a North American setting. Transshipment will only be economic when the cost per unit distance of a second transportation mode is less than the original mode. There is an optimum number of transshipment terminals which is related to biomass yield. Transshipment incurs incremental fixed costs, and hence there is a minimum shipping distance for rail transport above which lower costs/km offset the incremental fixed costs. For transport by dedicated unit train with an optimum number of terminals, the minimum economic rail shipping distance for straw is 170 km, and for boreal forest harvest residue wood chips is 145 km. The minimum economic shipping distance for straw exceeds the biomass draw distance for economically sized centrally located power plants, and hence the prospects for rail transport are limited to cases in which traffic congestion from truck transport would otherwise preclude project development. Ideally, wood chip transport costs would be lowered by rail transshipment for an economically sized centrally located power plant, but in a specific case in Alberta, Canada, the layout of existing rail lines precludes a centrally located plant supplied by rail, whereas a more versatile road system enables it by truck. Hence for wood chips as well as straw the economic incentive for rail transport to centrally located processing plants is limited. Rail transshipment may still be preferred in cases in which road congestion precludes truck delivery, for example as result of community objections.     

Quinazolines and 1,4-benzodiazepines. XCV. Synthesis of 1,4-benzodiazepines by ring expansion of 2-chloromethylquinazolines with carbanions

1,4-Benzodiazepines bearing a carbon substituent at the 2-position were obtained by reaction of 2-chloromethylquinazoline 3-oxides with stabilized carbanions. The carbanions of alkyl acetates, N,N-disubstituted acetamides, acetonitrile, dimethylsulfone, N,N-dimethyl methanesulfonamide and 2-methylpyridine were successfully applied. The conversion of some of the 2-carbon substituted 1,4-benzodiazepines to imidazo[1,5-a][1,4]benzodiazepines and [1,2,5]oxadiazino[5,4-a][1,4]benzodiazepines is described.     

A novel palladium-mediated coupling approach to 2,3-disubstituted benzo(b)thiophenes and its application to the synthesis of tubulin binding agents

[structure: see text]. Flexible, convergent access to 2,3-disubstituted benzo[b]thiophenes has been developed. The most concise approach involves sequential coupling of o-bromoiodobenzenes with benzylmercaptan and zinc acetylides to give benzyl o-ethynylphenyl sulfides which react with iodine to give 3-iodobenzo[b]thiophenes in a 5-endo-dig iodocyclization. These iodides can be further elaborated using palladium-mediated coupling and/or metalation techniques. This method has been applied to the synthesis of some novel tubulin binding agents.     

Laser induced time-dependent thermal lensing studies of vibrational relaxation: translational cooling in CH3F

Time-resolved measurements of the thermal lens effect have been made for CH₃F, CH₃CI and C₂H₄. This technique is compared to others used in the study of vibrational relaxation phenomena and is found to be applicable to the study of a wide variety of gaseous systems at relatively low pressures. Translational cooling has been observed in CH₃F and an approximate lower limit of 200 msec^-1 has been established for the rate of this cooling process, which corresponds to equilibration of the ν₃ and ν₆ states, in a mixture of 0.2 torr CH₃F and 10 torr Ar.