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Proton Abstraction from 4-Nitrophenyl[bis(ethylsulphonyl)]methane with TMG, TBD and MTBD Bases in Acetonitrile

100%

Jarczewski A. , Binkowska I.

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tom Vol. 75, nr 12

1895-1903

EN

4-Nitrophenyl[bis(ethylsulphonyl)]methane has been synthesized and used in kinetic studies of proton abstraction induced by 1,1,3,3-tetramethylguanidine (TMG), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and 7-methyI-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) bases in acetonitrile. The pK, values of this carbon acid in water and in acetonitrile solvents are 10.08 and 22.8 respectively. The electronic spectra of 4-nitrophenyl[bis(ethylsulphonyl)]methane and its anion ar well defined and temperaturę dependent. The rates of proton abstraction are large as the reaction occurs in the range of microseconds. The relaxation times were studied by spectrophotometric temperature-jump technique. The rate constants for proton transfer reaction promoted by TMG, TBD and MTBD bases in acetonitrile are: 1.39x10 5-2.1 Ix10 5; 8.8x10 6-19.2x10 6; 0.84x105-2.43x 10S [dm3 mol-1 s-1] respectively between 20-40°C. The enthalpies of activation are: deltaH# = 18.1, 28.7 and 40.0 [kJ mol-1] for TMG, TBD and MTBD respectively. The entropies of activation are all negative: deltaS# = -84.9, -13.6, -14.3 [J mol-1 deg-1] for the same sequence of bases reacting with 4-nitrophenyl[bis(ethylsulphonyl)]methane in acetonitrile solvent. The general discussion of the results obtained and their comparison with those for proton transfer reaction carried out with "normal" C-acids is given.

2

Anion Radical Formation in the Reaction of 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) with Tribenzylamine in Acetonitrile

100%

Dworniczak M. , Jarczewski A.

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tom Vol. 75, nr 11

1739-1743

EN

Kinetics of the reaction of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) with tribenzylamine in acetonitrile has been measured spectrophotometrically. The product of this reaction is a stable anion radical of DDQ. The reaction is relatively slow, due to a considerable steric hindrance in both quinone and amine molecule. Activation parameters indicate a charge separation in the transition state. The mechanism of the reaction has been proposed.

3

Influence of fatty acid methyl esters' additive to diesel engine on ecology, fuel consumption and vehicle's performance

80%

Chłopek Z. , Jarczewski A. , Bardziński W. , Sar H.

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tom Vol. 13, No. 1

261-268

EN

The paper presents results of researching a vehicle equipped with diesel engine, fueled by diesel fuel with fatty acid methyl esters' additive. Research was conducted on chassis dynamometer in static conditions (load characteristics) and dynamic road test cycles according to 83 ECE Regulation. On the basis of results the characteristics of average pollutants' emission, fuel consumption and exhaust opacity as a function of fatty acid methyl esters' additive to diesel fuel were made. Characteristics of engine's power and torque as a function of acid methyl esters' additive were also made. Research showed that together with increasing share of esters in diesel oil to 100% with reference to clean diesel oil there was taken place by the decreasing level of HC emission of 28 %, CO emission decreasing of 21%, increasing NOx emission of 8%, the smokiness decreasing of exhaust gases of 57%. Measurement of the fuel consumption with the method of the carbon balance showed increasing of the fuel consumption with the increasing of FAME share in the mixture. Growth volumetric fuel consumption clean esters with relation to the clean diesel oil carried out of 16%. There also was observed the essential decreasing of the smokiness of exhaust gases with increasing of FAME share. At to supply of the engine clean esters there was observed decreasing of the maximum power of 5. 1% with relation to supply clean diesel oil For the fuel of 10 % FAME decreasing of the engine power carries out about 0, 5 %.

PL

Artykuł prezentuje badania pojazdu zaopatrzonego w silnik diesla, zasilany olejem napędowym z c estrów metylowych kwasu tluszczowego(FAME). Badania były prowadzone na hamowni warunkach statycznych (charakterystyka obciążeniowa) i dynamicznych cyklach testu drogowego s Przepisów 83 ECE. Na bazie wyników charakterystyka średnich wartości składników toksycznych zużycie paliwa i wyglądu spalin zostały opracowane charakterystyki mocy silnika i momentu obrotowego w funkcji dodatku estrów metylowych do oleju napędowego. Badania wykazały, że wraz ze wzrostem udziału estrów w oleju napędowym do 100% w odniesieniu do czystego oleju napędowego nastąpił spadek poziomu emisji HC o 28 %, spadek emisji CO o 21%, wzrosłe NOX o 8%, spadek zadymienia spalin o 57%. Pomiary zużycia paliwa metodą bilansu węgla wykazały ł zużycia paliwa ze wzrostem udziałów FAMĘ w mieszaninie. Wzrost objętościowego zużycia czystych estrów w stosunku do czystego oleju napędowego wyniósł ok. 16%. Zaobserwowano też istotne zmniejszenie; spalin ze wzrostem udziału FAME. Przy zasilaniu silnika czystymi estrami zaobserwowano spadek i maksymalnej o 5,1% w stosunku do zasilania czystym olejem napędowym, dla paliwa z 10% dodatkiem FAME spadek mocy silnika wynosi około 0,5 %.

4

Zjawiska dysocjacji i asocjacji towarzyszące reakcjom przeniesienia protonu między C-kwasami i zasadami organicznymi w rozpuszczalnikach aprotonowych

80%

Nowak I. , Binkowska I. , Stańczyk-Dunaj M. , Jarczewski A.

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tom [Z] 62, 1-2

67-95

EN

The proton transfer reactions in solutions have attracted the attention of a number of laboratories for many years. These processes seem to be quite simple as they proceed without perturbation of bounding electrons and have low steric demands what enables study of their mechanism. However, many factors influences the mechanisms of these reactions. Among them and not the trifling ones, are dissociation-association effects accompanying them. The definition, behavior and reactivity of carbon acids (C-acids) depending on the type of electron withdrawing group are given [1-57]. Also the values of dissociation constants of C-acids in protic and aprotic solvents are collated in Tables 4, 5 and 7 [11, 38, 49]. The nature of products, free ions and ion pairs, of proton transfer reactions of various C-acids and strong organic bases are carefully discussed. Also their spectral characteristics are given. The equilibria and the possible routes between the substrates and the products of these reactions are also shown [58-66]. The reasons of the homoconjugation effects as a result of an association of the ionic products of the proton transfer reactions in different solvents are discussed in the context of their solvation abilities [67-86]. The formation constants of the homoconjugation complexes of amidine and guanidine bases in relation to their pK? values are quoted in Table 6 [87-95]. The nature of heteroconjugation complexes formed as the result of hydrogen bonding of different entities in the system of proton transfer reactions is discussed [96-116]. The pK? values of a number of C-acids, derivatives of nitromethane, measured in acetonitrile by potentiometric method, are given in Table 7. The pK? values of these derivatives measured in DMSO/H2O systems are compared with those obtained in acetonitrile [18, 38]. The general view of these problems is discussed and carefully reviewed.