摘要:

Basicity of KetonesThe determination of the protonation ratios of weak organic bases e. g. ketones in strong acidic solutions by means of NMR and UV spectroscopy is described. Different extrapolation procedures which allow to obtain the basicity and solvation parameters are presented and compared. Literature data for aliphatic, cyclic and aromatic ketones as well as diketones are collected and discussed in terms of structural and solvation effects on basicity.

ISSN:0941-1216    

DOI:10.1002/prac.19943360702

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe lifetime of cation selective carrier‐PVC‐membranes partially depends on the components' remaining in the membrane. An exchange of monomeric by polymeric plasticizers with low tendency to migrate lengthens the function time drastically. Other than for Na+‐ and NH 4+‐selective membranes, it is essential for K+‐ and Ca2+‐selective membranes and optional for H+‐selective membranes to incorporate lipophilic anions in order to make the phase transfer catalysis more efficient. The resistence to saponification of phthalic acid polyester gives H+‐selective membranes a high stability of measured values even in the alkaline range.For anion selective PVC‐membranes, instead of cation selective plasticizers the plasticizing qualities of a liquid charged ligand should be used.The tubular carrier‐PVC‐membranes of our ion selective flow through measuring systems are diffusion welded to the ends of two PVC‐tubes [1] so that they are absolutely tight with no risk of potential leakage. Migration of the membrane components plasticizer and ionophore across this border as well as their extraction [2, 3]into the measuring solution [4] will naturally reduce the membran

ISSN:0941-1216    

DOI:10.1002/prac.19943360703

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

Critical Micelle Concentration of Sulfobetaines in Anhydrous Hydrofluoric AcidUp to now only little attention has been paid to micellation in nonaqueous polar solvents. Anhydrous hydrogen fluoride should be a suitable medium for micellation. The CMC‐data of selected sulfobetaines in anhydrous hydrogen fluoride are determined by solubilisation measurements with hydrocarbons. The free energy of micelle formation and the dependence of the CMC‐data on temperature are given and dicus

ISSN:0941-1216    

DOI:10.1002/prac.19943360704

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe naphthalimide derivatives (2a–g, 3a–e) were synthesized from 1,8‐naphthalic carboximides. They show green fluorescence, and are suitable for dyenig of textile materials and epoxy resins. The colour parameters of the dyed fabrics were measured. The assessment of colour was made in terms of CIE tristimulus values as well as the position of colour in CIELAB coordinates (L*, a*, b*). The correlation between colour and structure of the dyes is disc

ISSN:0941-1216    

DOI:10.1002/prac.19943360705

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

Rhodium‐catalyzed Two‐phase Hydroformylation of Hex‐1‐ene with Sulfonated Tris(4‐fluorophenyl)phosphine as Water‐soluble Complex LigandsTris(4‐fluorophenyl)phosphine (TFPP) was prepared from 1‐bromo‐4‐fluoro‐benzene in 35% yield. This phosphine was quantitatively sulfonated by using a H2SO4‐SO3mixture containing 25,5% SO3and a 14‐fold excess of SO3to phosphine. The desired product was the trisodium salt of the trisulfonated tris(4‐fluorophenyl)phosphine (TFPPTS). After 410 hours of sulfonation, hydrolysis and pH‐selective separation, the resulting mixture contained 6% TFPPTS and 94% disodium salt of the disulfonated tris(4‐fluorphenyl)phosphine (TFPPDS).Hex‐1‐ene was hydroformylated in a two‐phase system by using the water‐soluble catalytic systems Rh4(CO)12with a mixture of 94% TFPPDS + 6% TFPPTS and Rh4(CO)12with the trisodium salt of trisulfonated triphenylphosphine (TPPTS). The TFPP or TFPPTS ligand possesses a stronger π‐acidity than the TPP or TPPTS and at low P/Ph‐ratios higher selectivities to linear aldehydes are achieved with the Rh/TFPP or Rh/TFPPDS + TFPPTS than with the Rh/TPP or Rh/TPPTS catalytic system. The Rh/TFPPDS + TFPPTS complex is quantitatively recovered by simple separation of the aqueous layer from the organic layer w

ISSN:0941-1216    

DOI:10.1002/prac.19943360706

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

Abstract3‐Acyl‐4‐hydroxy‐2(1H)‐quinolones5are obtained by hydrolytic ring opening and subsequent decarboxylation from the corresponding pyrano[3,2‐c]quinolin‐2,5(6H)‐diones4, which in turn are easily obtained from 1:2 condensation of anilines1with diethyl malonate2aor 1:1 condensation of diethyl alkyl‐ or arylmalonates2b–ewith 4‐hydroxy‐2(1H)‐quinolones3. Nitropyranoquinolinediones6furnish after ringopening 3‐nitroacetyl‐4‐hydroxy‐2(1H)quinolones8. Pyranoquinolines7and9with acetyl‐ or aminosubstituents are hydrolyzed

ISSN:0941-1216    

DOI:10.1002/prac.19943360707

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

Abstract2,5‐dihydrofuran1was galvanostatically oxidized in aqueous electrolytes on Pt and PbO2anodes at current densities of 10 to 50 mA cm−2. Under acidic conditions maleic dialdehyde2was obtained on both electrodes with a current efficiency (c.e) of up to 50%. In the alkaline region (pH 10) 4‐hydroxy crotonic aldehyde3(Pt) or 2,5‐dihydrofuranone4(PbO2) become the main products with c.e.'s of 29% and 27%, respectively, depending on the anode material. The influence of pH and of the anode material are discussed in detail. 2,3‐dihydrofuran7, vinyl ethyl ether8and for comparison, furan9were studied in

ISSN:0941-1216    

DOI:10.1002/prac.19943360708

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

ISSN:0941-1216    

DOI:10.1002/prac.19943360709

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

ISSN:0941-1216    

DOI:10.1002/prac.19943360710

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

ISSN:0941-1216    

DOI:10.1002/prac.19943360711

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY