Sveobuhvatna ljestvica nukleofugalnosti izlaznih skupina u odabranim otapalima

master's thesis

• Title (english): Comprehensive nucleofugality scale of leaving groups in chosen solvents
• Author: Viktorija Škiljan
• Mentor: Mirela Matić (mentor)
• Committee member: Mirela Matić (predsjednik povjerenstva)
• Committee member: Bernard Denegri (član povjerenstva)
• Committee member: Ana Budimir (član povjerenstva)
• Granter: University of Zagreb; Faculty of Pharmacy and Biochemistry; (Department of organic chemistry); Zagreb
• Defense date and country: 2023-05-12, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Pharmacy; Pharmacy

Abstract

Nukleofugalnost i elektrofugalnost predstavljaju reaktivnost izlaznih skupina koje nastaju reakcijama heterolize. Prilikom solvolize neutralnog spoja, nukleofug je izlazna skupina koja odnosi elektronski par i postaje anion, a elektrofug predaje elektrone i postaje kation. Njihovu kvantifikaciju omogućila je jednadžba koju su predložili Mayr i suradnici početkom 21. st. (log k (25 °C) = sf (Nf + Ef)), a koja opisuje nukleofugalnost Nf i sf, a elektrofugalnost Ef parametrom. Korelacija omogućuje semikvantitativno predviđanje konstanti brzina solvolize (i vremena polureakcije) što je važno u svakodnevnoj laboratorijskoj praksi za procjenu stabilnosti supstrata u otapalima, a sami parametri nukleofugalnosti međusobnu usporedbu reaktivnosti izlaznih skupina različitih struktura u pojedinom otapalu. Pregledom literature u ovom radu sakupljene su sve dosad objavljene eksperimentalne i izračunate vrijednosti nukleofugalnosti u odabranim organskim otapalima i njihovim smjesama s vodom te izrađena sveobuhvatna ljestvica. Opisana je i konstrukcija same ljestvice nukleofugalnosti te određivanje eksperimentalnih i izračunatih vrijednosti. Ukupan broj pronađenih vrijednosti nukleofugalnosti iznosi 1349, od kojih je 310 eksperimentalno određenih, a 1039 izračunatih. Najreaktivnijim izlaznim skupinama pokazali su se tosilat, mesilat i trinitrometil-karbonat, dok najmanje reaktivnim pripadaju prvenstveno karboksilati. Širok raspon reaktivnosti koji pokriva Mayrova jednadžba prikazan je na primjeru izračunatih konstanti brzina solvoliza supstrata sastavljenih od odabranih izlaznih skupina i elektrofuga različitih reaktivnosti.

Abstract (english)

Nucleofugality and electrofugality represent the reactivity of leaving groups which develop in heterolysis reactions. When neutral substrate undergoes solvolysis, nucleofuge is a leaving group that departs with an electron pair and becomes anion, while electrofuge gives its electrons over and becomes cation. Their quantification was made possible by an equation proposed by Mayr and coworkers at the beginning of 21st century (log k (25 °C) = sf (Nf + Ef)) in which nucleofugality is described with Nf and sf parameters and electrofugality with Ef parameter. Correlation enables semiquantitative estimation of solvolysis rate constants (and half-life) which is important in everyday laboratory practice for evaluation of substrate stability in solvents, and nucleofugality parameters alone made possible mutual comparison of leaving group reactivities of different structures in a certain solvent. This paper shows comprehensive nucleofugality scale comprised of all experimentaly obtained and calculated nucleofugality values in chosen organic solvents and their mixtures with water which have been published so far. The construction of the scale alone and determination of experimental and calculated nucleofugality values are described as well. Total number of nucleofugality values found by literature review is 1349, of which 310 were determined experimentally and 1039 were calculated. The most reactive leaving groups have proven to be tosylate, mesylate and trinitromethyl carbonate and the least reactive groups are primarily carboxylates. To illustrate wide reactivity range covered by Mayr equation, solvolysis rate constants were calculated for substrates comprised of chosen leaving groups and electrofuge of different reactivities.

• Keywords: nukleofugalnost; elektrofugalnost; konstanta brzine solvolize; ljestvica nukleofugalnosti
• Keywords (english): nucleofugality; electrofugality; solvolysis rate constant; nucleofugality scale
• Language: croatian
• URN:NBN: urn:nbn:hr:163:633946
• Study programme: Title: Pharmacy; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra farmacije (magistar/magistra farmacije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-05-15 15:39:43