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001-es BibID:	BIBFORM082761
Első szerző:	Balogh Ágnes
Cím:	Reaction Schemes That Are Easily Confused with a Reversible First-Order Reaction / Ágnes Balogh, Gábor Lente, József Kalmár, István Fábián
Dátum:	2015
ISSN:	0538-8066
Megjegyzések:	A detailed kinetic analysis of two schemes, one involving coupled consecutive pro-cesses and another featuring the simultaneous association reaction and decay of a component,is presented here using Taylor series expansion. It is shown that both of these schemes areeasily confused with the reversible second-order reaction in a routine kinetic study. The kinetictraces predicted by both schemes are sufficiently close to pseudo-first-order curves so that itis practically impossible to identify the deviations based on data with the usual experimentalerrors, which was also demonstrated by fitting simulated theoretical curves to exponentialfunctions. The dependence of the pseudo-first-order rate constants on the concentration ofthe excess reagent features the same trend as in the case of a reversible reaction: A straightline with an intercept is observed. This analysis emphasizes that the reversible nature of reac-tions should be demonstrated by direct equilibrium studies when elements of reversibility areimplied by kinetic results.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk
Megjelenés:	International Journal Of Chemical Kinetics. - 47 : 12 (2015), p. 773-782. -
További szerzők:	Lente Gábor (1973-) (vegyész) Kalmár József (1985-) (vegyész) Fábián István (1956-) (vegyész)
Pályázati támogatás:	TÁMOP-4.2.2.A-11/1/KONV-2012-0043 TÁMOP NK 105156 Egyéb
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
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001-es BibID:	BIBFORM079608
Első szerző:	Nagy Lajos (vegyész)
Cím:	Kinetics of Uncatalyzed Reactions of 2,4'- and 4,4'-Diphenylmethane-Diisocyanate with Primary and Secondary Alcohols / Lajos Nagy, Tibor Nagy, Ákos Kuki, Mihály Purgel, Miklós Zsuga, Sándor Kéki
Dátum:	2017
ISSN:	0538-8066
Megjegyzések:	The kinetics of the uncatalyzed reaction of an industrially important 50/50blend of isomers of 4,4·-diphenylmethane-diisocyanate (4,4-MDI) and 2,4·-diphenylmethane-diisocyanate (2,4·-MDI) with primary and secondary alcohols was studied using high-performance liquid chromatography coupled with photodiode array detector. The alcoholssuch as 1-propanol, 2-propanol, 1-hexanol, 2-hexanol, 3-hexanol, 1-methoxy-2-propanol, and3-methoxy-1-propanol were used in high molar excess to diisocyanate in toluene at 80?C, andpseudo?first-order dependences on the concentrations of 4,4·-MDI and 2,4·-MDI were found.Appropriate treatments of the kinetic data allowed us to determine the corresponding pseudo?first-order rate constants. According to the kinetic results, the reactivity of the isocyanate groupin the para-position is about four to six times higher than that of the ortho-positioned iso-cyanate group, depending on the reacting alcohol. Furthermore, the substitution effect, i.e.,change in the reactivity of the free isocyanate group after the other has been reacted, was foundfor both 4,4·-MDI and 2,4·-MDI isomers. The differences in the reactivities of the isocyanategroups of 2,4·-MDI and 4,4·-MDI isomers before and after one of two isocyanate groups hasbeen reacted are explained in terms of partial positive charges on the corresponding carbonylcarbon atom calculated by high-level quantum chemical calculations. In addition, the UV-spectral properties of the products obtained by quenching the reactionmixture with methanol are also discussed in light of practical implications.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk
Megjelenés:	International Journal of Chemical Kinetics. - 49 : 9 (2017), p. 643-655. -
További szerzők:	Nagy Tibor (1988-) (vegyész) Kuki Ákos (1966-) (villamosmérnök) Purgel Mihály (1982-) (vegyész) Zsuga Miklós (1944-) (polimer kémikus) Kéki Sándor (1964-) (polimer kémikus)
Pályázati támogatás:	GINOP-2.3.2-15-2016-00041 GINOP ÚNKP-16-3 Egyéb K-116465 egyéb
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
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