Immobilization of Burkholderia cepacia Lipase: Kinetic Resolution in Organic Solvents, Ionic Liquids and in Their Mixtures

Immobilization of Burkholderia cepacia Lipase: Kinetic Resolution in Organic Solvents, Ionic Liquids and in Their Mixtures Biocatalysis opens the door to green and sustainable processes in synthetic chemistry allowing the preparation of single enantiomers, since the enzymes are chiral and accordingly able to catalyze chemical reactions under mild conditions. Immobilization of enzymes enhances process robustness, often stabilizes and activates the enzyme, and enables reuse of the same enzyme preparation in multiple cycles. Although hundreds of variations of immobilization methods exist, there is no universal method to yield the highly active, selective and stable enzyme catalysts. Therefore, new methods need to be developed to obtain suitable catalysts for different substrates and reaction environments. Lipases are the most widely used enzymes in synthetic organic chemistry. The literature part together with the experimental part of this thesis discusses of the effects of immobilization methods mostly used to enhance lipase activity, stability and enantioselectivity. Moreover, the use of lipases in the kinetic resolution of secondary alcohols in organic solvents and in ionic liquids is discussed. The experimental work consists of the studies of immobilization of Burkholderia cepacia lipase (lipase PS) using three different methods: encapsulation in sol-gels, cross-linked enzyme aggregates (CLEAs) and supported ionic liquids enzyme catalysts (SILEs). In addition, adsorption of lipase PS on celite was studied to compare the results obtained with sol-gels, CLEAs and SILEs. The effects of immobilization on enzyme activity, enantioselectivity and hydrolysis side reactions were studied in kinetic resolution of three secondary alcohols in organic solvents, in ionic liquids (ILs), and in their mixtures. Lipase PS sol-gels were shown to be active and stable catalysts in organic solvents and solvent:IL mixtures. CLEAs and SILEs were highly active and enantioselective in organic solvents. Sol-gels and SILEs were reusable in several cycles. Hydrolysis side reaction was suppressed in the presence of sol-gels and CLEAs.

Annual and seasonal changes in production and composition of grazed clover-grass mixtures in organic farming

Selostus: Alsike-, puna- ja valkoapilan vaikutus laitumen tuottoon luonnonmukaisessa tuotannossa

β-Glucan contents of groats of different oat cultivars in official variety, in organic cultivation, and in nitrogen fertilization trials in Finland

Selostus: Kauran ytimen β-glukaanipitoisuus

Photoexcitation dynamics in organic solar cell donor/acceptor systems

Solceller presenteras ofta som ett miljövänligt alternativ för energiproduktion. Det största hindret för en bredare ibruktagning av kiselbaserade solceller är deras höga pris. I och med upptäckten av ledande och halvledande organiska (kolbaserade) molekyler och polymerer har ett nytt forskningsområde, organisk elektronik, vuxit fram. Den stora fördelen med organisk elektronik är att de använda materialen oftast är lösliga. Tillverkning av elektroniska komponenter kan då göras med hjälp av konventionella trycktekniker där bläcket ersatts med upplösta organiska material. Detta har potential att betydligt sänka priset för solceller. Nackdelen med organisk elektronik är att de använda materialen är komplexa, och de fysikaliska processerna i dem likaså. I min avhandling har jag studerat fotofysiken i två polymerer, P3HT och APFO3, som kan användas för att tillverka organiska solceller. Blandade med fullerenderivatet PCBM, som är en stark elektronacceptor, fås ett material som effektivt producerar elektroner och hål under belysning. I praktiken bidrar dock inte alla skapade laddningar till strömmen ur solcellen. Elektronerna och hålen kan förbli bundna till varandra i olika exciterade tillstånd, och även de som är fria kan träffa på motsatta laddningar under vägen till kontakterna och rekombinera. Centralt i mitt arbete har varit att identifiera olika typer av exciterade tillstånd i dessa solcellsmaterial, samt att bestämma deras livstider och rekombination. Metoden för detta har varit s.k. fotoinducerad absorption, som mäter fotoexcitationernas absorptioner i infraröda våglängdsområdet. De två viktigaste resultaten som presenteras i avhandlingen är en ratekvationsmodell för fotoexcitationsdynamiken i APFO3 på ultrasnabba tidsskalor (femtosekund - microsekund) och bildandet av en rekombinationshämmande dipol vid gränsytan för P3HT och PCBM som följd av värmebehandling. Dessa resultat bidrar till förståelsen av de fotofysikaliska processerna i relaterade material.

Recovery of carboxylic acids from aqueous streams by extraction and back extraction

Separation of carboxylic acids from aqueous streams is an important part of their manufacturing process. The aqueous solutions are usually dilute containing less than 10 % acids. Separation by distillation is difficult as the boiling points of acids are only marginally higher than that of water. Because of this distillation is not only difficult but also expensive due to the evaporation of large amounts of water. Carboxylic acids have traditionally been precipitated as calcium salts. The yields of these processes are usually relatively low and the chemical costs high. Especially the decomposition of calcium salts with sulfuric acid produces large amounts of calcium sulfate sludge. Solvent extraction has been studied as an alternative method for recovery of carboxylic acids. Solvent extraction is based on mixing of two immiscible liquids and the transfer of the wanted components form one liquid to another due to equilibrium difference. In the case of carboxylic acids, the acids are transferred from aqueous phase to organic solvent due to physical and chemical interactions. The acids and the extractant form complexes which are soluble in the organic phase. The extraction efficiency is affected by many factors, for instance initial acid concentration, type and concentration of the extractant, pH, temperature and extraction time. In this paper, the effects of initial acid concentration, type of extractant and temperature on extraction efficiency were studied. As carboxylic acids are usually the products of the processes, they are wanted to be recovered. Hence the acids have to be removed from the organic phase after the extraction. The removal of acids from the organic phase also regenerates the extractant which can be then recycled in the process. The regeneration of the extractant was studied by back-extracting i.e. stripping the acids form the organic solution into diluent sodium hydroxide solution. In the solvent regeneration, the regenerability of different extractants and the effect of initial acid concentration and temperature were studied.

Interfacial effects in organic solar cells

Solceller baserade på organiska halvledare erbjuder en möjlighet till storskalig och billig solenergiproduktion. Organiska halvledare har den fördelen att de är lösningsprocesserbara vilket gör att solceller och andra elektroniska komponenter baserade på dessa halvledare kan tillverkas vid låga temperaturer och med liten energiförbrukning. Nackdelen med dessa material är deras strukturella och energetiska oordning som leder till lägre effektivitet. För att organiska solceller ska kunna kommersialiseras krävs grundläggande insikter i de olika processer som begränsar effektiviteten. En stor del av forskningen om dessa processer har varit fokuserad kring egenskaperna av solcellens olika komponenter (de aktiva materialen) som sådana, medan gränsytorna mellan olika material har fått mindre uppmärksamhet. Gränsytor mellan olika material har distinkt olika egenskaper jämfört med ett rent material, och gränsytors olika egenskaper kan ha en väldigt stor inverkan på hur solcellerna fungerar. Syftet med denna avhandling är att klargöra några olika gränsyterelaterade effekter i organiska dioder och solceller. De gränsytor som behandlas är gränsytan mellan kontakten och det aktiva lagret (metall-organisk) och gränsytan mellan donor och acceptor (organisk-organisk). Resultaten visar att metall-organiska gränsytor måste designas noggrant för att begränsa förlust av effektivitet. En icke-idealisk kontakt leder till starkt reducerad effektivitet på grund av att elektronerna extraheras ineffektivt. Även till synes idealiska kontakter kan orsaka förluster genom spontan laddningsöverföring från metallen till det organiska lagret som effektivt sett minskar på den spänning som cellen kan alstra. Den organisk-organiska gränsytan påverkar hur mycket ström cellen kan alstra och beroende på gränsytans beskaffenhet kan de negativa rekombinationsprocesserna i materialet kontrolleras. ------------------------------------------------- Orgaanisille puolijohteille perustuvat aurinkokennot mahdollistavat suurimuotoisen ja edullisen aurinkoenergiatuotannon. Orgaanisten puolijohteiden etu on että ne voidaan liuottaa, jolloin aurinkokennot ja muut näille johteille perustuvat elektroniset komponentit voidaan valmistaa alhaisessa lämpötilassa kuluttaen vähän energiaa. Materiaalien huonona puolena on kuitenkin niiden rakenteellinen ja energeettinen epäjärjestys, jonka seurauksena niiden tehokkuus on huonompi. Orgaanisten aurinkokennojen kaupallistaminen edellyttää perustavanlaatuista ymmärystä tehokkuutta rajoittavista prosesseista. Aurinkokennotutkimus on pääosin keskittynyt aurinkokennon eri komponenttien (aktiivisten materiaalien) ominaisuuksiin, kun taas eri materiaalien rajapinnat ovat jääneet vähemmälle huomiolle. Eri materiaalien välisillä rajapinnoilla on huomattavan erilaisia ominaisuuksia verrattuna puhtaisiin materiaaleihin. Rajapintojen ominaisuudet voivat kuitenkin vaikuttaa merkittävästi aurinkokennojen toimintaan. Tämän väitöstutkimuksen tarkoituksena on selventää joitain rajapintoihin liittyviä toimintoja orgaanisissa diodeissa ja aurinkokennoissa. Käsiteltävät rajapinnat ovat rajapinta kontaktin ja aktiivisen kerroksen välillä (metallis-orgaaninen) ja rajapinta donorin ja akseptorin välillä (orgaanis-orgaaninen). Tutkimustulokset osoittavat, että metallis-orgaaniset rajapinnat tulee suunnitella huolellisesti, jotta tehokkuuden alenemista voidaan rajoittaa. Mikäli kontakti ei ole ideaalisti suunniteltu, vähenee tehokkuus huomattavasti, mikä johtuu elektronien tehottomasta ekstrahoinnista. Jopa ideaalisilta vaikuttavat kontaktit voivat johtaa tehokkuuden alenemiseen, mikäli varaus siirtyy spontaanisti metallista orgaaniseen kerrokseen, sillä tämä alentaa jännitettä jonka kenno voi tuottaa. Kennon orgaanis-orgaaninen rajapinta vaikuttaa siihen, kuinka paljon virtaa kenno pystyy tuottamaan. Rajapinnan ominaisuuksista riippuen materiaalin rekombinaatio on hallittavissa.

Studies on chemoenzymatic synthesis: Lipase-catalyzed acylation in multistep organic synthesis

In this thesis, biocatalysis is defined as the science of using enzymes as catalysts in organic synthesis. Environmental aspects and the continuously expanding repertoire of available enzymes have firmly established biocatalysis as a prominent means of chemo-, regio- and stereoselective synthesis. Yet, no single methodology can solve all the challenges faced by a synthetic chemist. Therefore, the knowledge and the skills to combine different synthetic methods are relevant. Lipases are highly useful enzymes in organic synthesis. In this thesis, an effort is being made to form a coherent picture of when and how can lipases be incorporated into nonenzymatic synthesis. This is attempted both in the literature review and in the discussion of the results presented in the original publications contained in the thesis. In addition to lipases, oxynitrilases were also used in the work. The experimental part of the thesis comprises of the results reported in four peer-reviewed publications and one manuscript. Selected amines, amino acids and sugar-derived cyanohydrins or their acylated derivatives were each prepared in enantio- or diastereomerically enriched form. Where applicable, attempts were made to combine the enzymatic reactions to other synthetic steps either by the application of completely separate sequential reactions with isolated intermediates (kinetic and functional kinetic resolution of amines), simultaneously occurring reactions without intermediate isolation (dynamic kinetic resolution of amino acid esters) or sequential reactions but without isolating the intermediates (hydrocyanation of sugar aldehydes with subsequent diastereoresolution). In all cases, lipase-catalyzed acylation was the key step by which stereoselectivity was achieved. Lipase from Burkholderia cepacia was a highly selective enzyme with each substrate category, but careful selection of the acyl donor and the solvent was important as well.

Mass transfer and reaction kinetics in single droplet systems

As reactive extraction grown more and more popular in a variety of technological applications, optimizing its performance becomes more and more important. The process of complex formation is affected by a great number of both physical and chemical properties of all the components involved, and sometimes their interference with one another makes improving the effectiveness of such processes very difficult. In this Master’s Theses, the processes of complex formation between the aqueous phase - represented by copper sulfate water solution, and organic phase – represented by Acorga M5640 solvent extractor, were studied in order to establish the effect these components have on reactive extraction performance and to determine which step is bottlenecking the process the most.

Sterolin valmistus selluprosessin yhteydessä

Työssä tutkittiin UPM-Kymmene Oyj Kaukaan kemiallisella tehtaalla käytössä olevia steroliprosesseja. Steroleita erotetaan sulfaattiselluloosan keitossa syntyvasta suovasta uutetusta neutraaliainejakeesta. Neutraaliaine sisältää β-sitosterolia, α-sitosterolia ja kampesterolia yhteensä noin 20 p-%. Primal-laadun valmistus perustuu neste-nesteuuttoon sekä kiteytykseen ja Ultra-laadun kaksivaiheiseen suorakiteytykseen. Työn kirjallisessa osassa perehdytään sterolien kemiaan sekä neste-nesteuuttoon ja kiteytykseen erotus- ja puhdistusmenetelminä. Laboratoriokokeissa tutkittiin kolmen eri alkoholin ja kahden eri hiilivetyliuottimen soveltuvuutta Primal-sitosterolin uuttoon ja kiteytykseen. Lisaksi tutkittiin liuotinseoksen vesipitoisuuden vaikutusta. Tavoitteena oli löytää uuttoliuottimien koostumus, jolla uuton sterolisaanto ja sterolikiteiden puhtaus olisivat mahdollisimman korkeat. Havaittiin, että uuton sterolisaanto voitiin maksimoida pitämällä uuttoalkoholin vesipitoisuus niin alhaisena, että faasit juuri ja juuri erottuvat toisistaan. Laboratoriokokeissa saatujen tulosten perusteella tehtiin tehdasmittakaavan koeajo Primal-sitosterolin valmistuslaitteistolla UPM-Kymmene Oyj Kaukaan kemiallisella tehtaalla. Talloin uutossa saavutettiin noin 50 %:n sterolisaanto. Ultra-sitosterolin laboratoriomittakaavaisissa kiteytyskokeissa vertailtiin neljän eri alkoholin ja kahden muun orgaanisen liuottimen soveltuvuutta kiteytysliuoksen komponenteiksi. Lisaksi tutkittiin vesipitoisuuden liuotinseoksen vaikutusta. Tarkoituksena oli löytää se liuotinkoostumus, jolla sterolikiteiden saanto ja puhtaus olisivat mahdollisimman korkeat. Sopivalla kiteytysliuoksen koostumuksella saavutettiin melko hyvä sterolisaanto ja lähes 98 %:n puhtaus.

Chelating Adsorbents in Purification of Hydrometallurgical Solutions

In this thesis, equilibrium and dynamic sorption properties of weakly basic chelating adsorbents were studied to explain removal of copper, nickel from a concentrated zinc sulfate solution in a hydrometallurgical process. Silica-supported chelating composites containing either branched poly(ethyleneimine) (BPEI) or 2-(aminomethyl)pyridine (AMP) as a functional group were used. The adsorbents are commercially available from Purity Systems Inc, USA as WP-1® and CuWRAM®, respectively. The fundamental interactions between the adsorbents, sulfuric acid and metal sulfates were studied in detail and the results were used to find the best conditions for removal of copper and nickel from an authentic ZnSO4 process solution. In particular, the effect of acid concentration and temperature on the separation efficiency was considered. Both experimental and modeling aspectswere covered in all cases. Metal sorption is considerably affected by the chemical properties of the studied adsorbents and by the separation conditions. In the case of WP-1, acid affinity is so high that column separation of copper, nickel and zinc has to be done using the adsorbent in base-form. On the other hand, the basicity of CuWRAM is significantly lower and protonated adsorbent can be used. Increasing temperature decreases the basicity and the metals affinity of both adsorbents, but the uptake capacities remain practically unchanged. Moreover, increasing temperature substantially enhances intra-particle mass transport and decreases viscosities thus allowing significantly higher feed flow rates in the fixed-bed separation. The copper selectivity of both adsorbents is very high even in the presence of a 250-fold excess of zinc. However, because of the basicity of WP-1, metal precipitation is a serious problem and therefore only CuWRAM is suitable for the practical industrial application. The optimum temperature for copper removal appears to be around 60 oC and an alternative solution purification method is proposed. The Ni/Zn selectivity of both WP-1 and CuWRAM is insufficient for removal of the very small amounts of nickel present in the concentrated ZnSO4 solution.