Encimska pretvorba 5-hidroksimetilfurfurala (HMF) do 2,5-furandikarboksilne kisline (FDCA) in karakterizacija fizikalnih lastnosti kislinskih derivatov HMF

Virant, Gašper (author), Kogej, Ksenija (mentor), Likozar, Blaž (co-mentor)

Glede na naraščajoči trend svetovne populacije, izčrpavanje fosilnih virov in glede na očitne podnebne spremembe, je razvoj zelenih in trajnostno naravnanih tehnologij čedalje bolj pomemben. Lignocelulozna biomasa je bogato prisoten obnovljiv vir iz katerega lahko proizvajamo vrsto platformskih kemikalij. Primer je 5-hidroksimetilfurfural (HMF), produkt dehidracije glukoze in fruktoze, ki ga pridobivamo z depolimerizacijo celuloze. HMF lahko preko tristopenjske oksidacije pretvorimo do 2,5- furandikarboksilne kisline (FDCA). Slednjo je Ameriški Sektor za Energijo (DOE) uvrstil na seznam 12 najpomembnejših platformskih kemikalij pridobljenih iz biomase. FDCA ima zaradi strukturne podobnosti s tereftalno kislino priložnost izpodriniti ogromen delež fosilno-osnovane polietilen-tereftalatne (PET) plastike in jo zamenjati z bioplastiko. Tristopenjsko oksidacijo HMF do FDCA lahko dosežemo po kemijski poti, vendar ta zahteva uporabo dragih katalizatorjev, visokega tlaka in temperature ter toksičnih organskih topil. V zadnjem času zasledimo porast raziskav usmerjenih v encimsko oksidacijo HMF do FDCA, ki je precej bolj ekološka, saj ta poteka pri sobnem tlaku in temperaturi. V magistrskem delu smo tristopenjsko oksidacijo HMF do FDCA razdelili na posamezne intermediate in testirati katalitično aktivnost šestih komercialno dostopnih encimov: alkohol oksidaze, galaktoze oksidaze, katalaze, lakaze, lignin peroksidaze in hrenove peroksidaze. Aktivnost encimov smo testirali na vse intermediate v omenjeni oksidacijski poti. Katalitične aktivnosti so bile nizke z izjemo, ko je bil substrat 5-formil- 2-furankarboksilna kislina (FFCA), ki je bila v nekaterih primerih pretvorjena v FDCA z izkoristki večjimi od 80 %. Določili smo tudi nekatere fizikalno-kemijske lastnosti kislinskih derivatov HMF, kjer smo ugotovili, da slednji v raztopinah tvorijo asociate. Kislinskim derivatom HMF smo na podlagi kvantnomehanskega pristopa izračunali elektronsko gostoto in določili njihove pKa vrednosti.

• Language: Slovenian
• Keywords: bio-osnovane kemikalije, 2, 5-furandikarboksilna kislina, FDCA, 5- hidroksimetilfurfural, HMF, encimska sinteza FDCA, medmolekulska asociacija
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2020
• PID: 20.500.12556/RUL-121553
• COBISS.SI-ID: 38277379
• Publication date in RUL: 15.10.2020

Secondary language

• Language: English
• Title: Enzymatic conversion of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) and characterisation of physical properties of the HMF acid derivates

Abstract

With the rapid growth of the world population and continuing depletion of petroleum reserves, green approaches using renewable resources for the production of chemicals will be required. Lignocellulosic biomass is an abundant, inexpensive, and sustainable resource from which platform chemicals can be derived. 5-Hydroxymethylfurfural (HMF) is derived from cellulose via dehydration of glucose and fructose. HMF can be further converted to 2,5-furandicarboxylic acid (FDCA) through three-step oxidation. The latter is listed as one of twelve top biomass-derived value-added chemicals by the American Department of Energy (DOE). The most promising application of FDCA is the replacement of fossil-based terephthalic acid in synthesis of polyethylene terephthalate (PET) plastics. Three-step oxidation of HMF to FDCA can be achieved via chemical pathway, but it requires special catalysts, high pressure and temperature and organic solvents which make process environmentally unfriendly and costly. A lot of research has been recently pointed into enzymatic conversion of HMF to FDCA which, by contrast, requires mild conditions such as room pressure and temperature, producing less toxic waste and is thus eco-friendlier. In present master thesis we studied catalytic activity of six commercially available enzymes: alcohol oxidase, galactose oxidase, catalase, laccase, lignin peroxidase and horseradish peroxidase in field of oxidising HMF to FDCA. We broke down the aforementioned three-step oxidation to separate reactions to determine all the possible substrates as well as reaction products for each individual enzyme. The product yields obtained with these single-enzyme reactions were mostly low, except in case when the substrate was 5-formyl-2-furancarboxylic acid (FFCA), where some of the yields of the conversion of FFCA to FDCA exceeded 80 %. We have also determined some of the physical properties of the HMF acid derivatives, where we found that they form associates in solutions. Based on quantum mechanics approach we calculated electron density for each exanimated HMF acid derivative as well we determined corresponding pKa values.

• Keywords: bio-based chemicals, 2, 5-furandicarboxylic acid, FDCA, 5- hidroxymethylfurfural, HMF, enzymatic preparation of FDCA, intermolecular association