Parameter-free structure-property correlation via progressive reaction posets for substituted benzenes

Progressive reaction networks as frequently arise in chemistry are naturally identifiable as "partially ordered sets" (or posets). Here the direction of the reaction identifies the partial ordering of the set of molecular species. The possibility that different properties are similarly ordered is a further natural consideration and is here investigated for a suite of over 30 properties for (methyl and chloro) substituted benzenes. Such a posetic correlation is favorably demonstrated for these substituted benzenes, and it is illustrated how suitable properties may be simply predicted in an interpolative parameter-free (albeit not model-free) fashion through the use of the reaction poset. Some numerical model-quality indicators are identified, and the simple approach is deemed quite reasonable.     

Pre-resonance Raman intensity studies of TCNQ and TCNQ−

Pre-resonance Raman spectra have been obtained for TCNQ and LiTCNQ in acetonitrile solution using an Ar⁺—Kr⁺ laser and a tunable rhodamine 6G dye laser. Using the theory of Albrecht and Hutley, we have calculated frequency factors for the intensity variations for several symmetric vibrational modes of each molecule. The observed spectra for TCNQ and LiTCNQ with violet, blue, and green excitation give evidence for B-type resonance enhancement due to vibronic mixing between at least two violet and ultraviolet transitions. The Raman spectra for LiTCNQ with yellow, orange, and red excitation show A-type enhancement due to a single electronic excitation in the near infrared.     

Formation and Crystal Structure of Stable Five‐coordinate Diorgano Cobalt(III) Complexes

The mer‐octahedral complexes(2‐carbonyl)(4‐Me)(6‐tBu)phenolato[C,O]hydridotris(trimethylphosphine)cobalt(III) ( 1 ) or ‐(1‐carbonyl)(2‐oxo)(1,2‐diphenylethene)[C,O]hydridotris(trimethylphosphine)cobalt(III) ( 2 ) via formal insertion of propynoic acid ethyl ester into Co‐H functions afford pentacoordinate vinylcobalt(III) 3 and 4 , respectively, that are diamagnetic and attain a square pyramidal structure as exemplified by an X‐ray diffraction analysis of 3 .     

Semiconductor gas sensors in bioreactor control

A simple semiconductor gas sensor (TGS 812) is used for the on-line measurement and control of indole during the production of l-tryptophan from indole and l-serine with immobilized E. coli cells. Indole is estimated in the reactor gas space. In combination with an automatic indole supply system, a feed-batch process became possible. The indole concentration was monitored and kept within the optimal range (300–600 mg l^?1). A simple gas-sensing electrode dipped in the reaction medium provides direct measurement of organic solvents and gases in the liquid. Such a system is suitable for on-line determination of ethanol (10–70 g l^?1) during continuous production of ethanol with immobilized yeast cells.     

13C nuclear magnetic resonance spectra—VI: Stereochemical dependence of γanti,heterosubstituent effects on 13C chemical shifts of bridgehead substituted molecules

The ¹³C NMR data of some mono- and disubstituted adamantanes, homoadamantenes and homonoradamantenes are presented. A model of dependencies of the γ_anti substituent induced shifts on torsion angles and internuclear distances between substituents and the γ carbons is proposed. Furthermore, it is shown that for the α substituent induced shifts strain within the molecular frameworks of these compounds plays no significant part.     

Mild and practical cycloaddition reactions of furans with phenyl vinyl sulfonate

Phenyl vinyl sulfonate reacts with various alkyl furan derivatives under mild conditions to produce excellent yields of the corresponding cycloadducts.     

Benzodiazepine analogues. Part 21. 13C NMR analysis of benzoxathiepine derivatives

The influence of substituents and structure on the 13C NMR spectra of four series of benzoxathiepine derivatives has been investigated. Signal assignments in the 13C NMR spectra have been facilitated by the use of several predictive methods, permitting comparison of their relative efficacy.     

Synthesis of pyrrolo[1,2-b]cinnolines

The synthesis of the pyrrolo[1,2-b]cinnoline analogs 2 and 4–13 is described. The key step of this synthesis involves an intramolecular aromatic halide displacement on [2-(2-halobenzoyl)pyrrol-1-yl]carbamic acid esters. Several reactions of these cinnoline analogs with electrophilic reagents have been investigated.