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Synthesis of new hydrazone derivatives of vitamine B6, pyridine-4-carbaldehyde and 2-quinolinecarbaldehyde
No full textU radu su sintetizirani hidrazonski derivati vitamina B6, piridin-4-karbaldehida te 2-kinolinkarbaldehida (1-15). Za sintezu su korišteni fenil-hidrazin te supstituirani fenil-hidrazini: 2,4-dinitrofenil-hidrazin, 4-klorfenil-hidrazin, 4-fluorfenil-hidrazin, 4-metilfenil-hidrazin. Reakcije su izvedene u dva različita otapala, acetonu i etanolu kako bi se ispitao utjecaj polarnosti i apsorpcijske moći otapala na iskorištenje reakcije. Sinteze su se odvijale pod utjecajem mikrovalnog zračenja, ekološki prihvatljivijom metodom kojom se u znatno kraćem vremenu može dobiti željeni produkt. U radu je ispitano kako mikrovalno zračenje kao jedno od alternativnih metoda sinteze i odabir otapala utječu na kemijska iskorištenja u odnosu na konvencionalne metode sinteze hidrazonskih derivata. Dobiveni rezultati uspoređeni su s istraživanjima drugih autora koji su slične ili iste hidrazone dobili klasičnom organskom sintezom.Hydrazone derivatives of vitamin B6, pyridine-4-carbaldehyde and 2-quinolinecarbaldehyde (1-15) were synthesized in this thesis. Phenyl-hydrazine and substituted phenyl-hydrazines were used for the synthesis: 2,4-dinitrophenyl-hydrazine, 4-chlorophenyl-hydrazine, 4-fluorophenyl-hydrazine, 4-methylphenyl-hydrazine. Reactions were performed in two different solvents, acetone and ethanol to examine the effect of solvent polarity and absorption power on reaction yield. The syntheses were carried out under the influence of microwave radiation, a more environmentally friendly method by which the desired product can be obtained in a much shorter time. The thesis examines how microwave radiation as one of the alternative methods of synthesis and the choice of solvent affect the chemical yields compared to conventional methods of synthesis of hydrazone derivatives. The obtained results were compared with the researches of other authors who obtained similar or the same hydrazones by classical organic synthesis
Organometallic compounds of d-block elements
No full textOrganski spojevi koji posjeduju minimalno jednu kovalentnu vezu između atoma ugljika i atoma metala klasificiraju se kao organometalni spojevi. Metal u metalnim karbonilima istog koordinacijskog broja poput oksidacijskog stanja podliježe 18 - elektronskom pravilu. U slučaju istih orbitalnih karekteristika dva fragmenta klastera definiraju se kao izolobalna. Primjena izolobalnog odnosa uzmeđu klastera na Wade-ovo pravilo omogućava njegovu primjenu pri brojanju elektrona jednostavnih organometalnih spojeva. Mingosovo pravilo nalazi primjenu pri brojanju ukupnog broja valentnih elektrona polinuklearnih organometalnih spojeva u slučaju kada se Wade-ovim pravilom isti ne mogu strukturno opisati. Najvažnije organometalne reakcije su β-hidrogen eliminacija, α-hidrogen apstrakcija, supstitucija CO ligand, migracija vodika i alkila te oksidativna adicija.Organic compounds that have at least one covalent bond between carbon atoms and metal atoms are classified as organometallic compounds. Metal in metal carbonyls of the same coordination number as oxidation state is subject to an 18- electron rule. In the case od the same orbital characteristics, 2 cluster fragments are defined as isolobal. The application of the isolobal relationship between clusters to the Wade rule allows it to be applied in the case of counting electrons of simple organometallic compounds. The Mingos rule finds application in counting the total number of valent electrons of polynuclear organometallic compounds when the Wade rule can not structurally describe them. The most important organometall reactions are: β-hydrogen elimination, α-hydrogen abstraction, CO ligand substitution, hydrogen and alkyl migration and oxidative addition
Reduction of aldehydes to alcohols
No full textAlkoholi su organski spojevi koji sadrže hidroksilnu funkcijsku skupinu (-OH) vezanu na sp3 hibridizirani ugljikov atom. Za razliku od alkana i alkil halogenida, ova skupina ima dvije reaktivne kovalentne veze, C - O i O - H vezu, koje snažno pridonose fizikalnim svojstvima alkohola. Mogu se pripremiti iz različitih vrsta spojeva, a jedan on načina je redukcijom aldehida. Najčešće korišteni redukcijski reagens pri redukciji aldehida jest . U ovom radu sintetizirana su dva alkohola iz odgovarajućih dialdehida. Reakcija je izvedena uz pomoć redukcijskog sredstva u tetrahidrofuranu i etanolu kao reakcijskom mediju. Nastali produkti su karakterizirani FT-IR spektroskopijom i NMR spektroskopijom, te im je određena temperatura tališta.Alcohols are organic compounds that contain a hydroxyl functional group (-OH) attached to an sp3 hybridized carbon atom. Unlike alkanes and alkyl halides, this group has two reactive covalent bonds, the C - O and O - H bonds, which strongly contribute to the physical properties of alcohol. They can be prepared from many different types of compounds, and one way is to reduce the aldehydes. The most commonly used reducing reagents is . In this thesis, two alcohols were synthesized from the aldehydes. The reaction was performed using the reducing agent in tetrahydrofuran and ethanol as a reaction medium. Synthesized products were characterized by FT-IR spectroscopy, NMR spectroscopy, and their melting point was determined
Application of electroanalytical methods in analytical chemistry
No full textElektroanalitičke metode su metode koje imaju široku primjenu. Pomoću tih metoda proučavamo kemijske promjene, odnosno interakcije na molekulskoj i atomskoj razini, koje nastaju utjecajem električne struje koja protječe elektrokemijskim člankom. Svojstva električne struje, direktno ili indirektno, su povezana s koncentracijom analita u otopini koja se ispituje. S obzirom na svojstva struje koja prolazi elektrokemijskim člancima razlikujemo: amperometriju, polarografiju, potenciometriju, kulometriju, konduktometrije te elektrogravimetriju. Najpogodnija metoda je ona koja je najosjetljivija, najpreciznija i najtočnija za određeni eksperiment, ovisno o analitu. U ovom radu opisat će se navedene metode te navesti njihova primjena u svakodnevnom životu.Electroanalytical techniques encompass a wide range of quite diverse methods such as amperometry, potentiometry, polarography, culometry, conductometry and electrogravimetry. Electroanalitical methods study chemical reactions, on molecular and atomic level, induced by electricity. Properities of eletricity depend, directly or indirectly, on concentration of analyte. The most convenient method is the one that is sensitive and precise for a specific analyte in experiment. This paper presents an overview of earlier mentioned electroanalytical methods and their implication in everyday life
Investigation of the influence of interferences on response of the senzor with functionalized carbon nanotubes to anionic surfactants
No full textOrganske tvari koje smanjuju površinsku napetost tekućina između dviju faza koje se međusobno ne miješaju se nazivaju tenzidi. Svaki tenzid je po svojoj strukturi amfifilni spoj što znači da se molekula sastoji od hidrofilnog i hidrofobnog dijela. Hidrofilni dio molekule tenzida koji se ujedno zove i glava sadrži polarne funkcionalne skupine koje mogu sadržavati različite naboje. S obzirom na naboj koji se nalazi na hidrofilnoj glavi tenzide možemo podijeliti u četiri kategorije: anionski, kationski, neionski i amfoterni. Hidrofobni dio svakog tenzida se sastoji od dugačkog alifatskog ugljikovodičnog lanca koji može biti ravni, razgranati ili aromatski. Hidrofilna glava anionskog tenzida otpušta negativno nabijene površinski aktivne ione prilikom disocijacije u vodenim otopinama. Analize tenzida se često izvode pomoću potenciometrijskih metoda koje se temelje na određivanju koncentracije tenzida mjerenjem elektrokemijskog potencijala sustava koji se sastoji od dviju vrsta elektroda, indikatorske i referentne. Kao indikatorska elektroda tijekom eksperimenta korištena je tenzidno-selektivna elektroda koja sadrži tekuću membranu u koju je ugrađen senzorski materijal s višestjenčanim ugljikovim nanocjevčicama i tetrafenilboratom (MWCNT-TPB). Odziv MWCNT-TPB senzora na anionski tenzid natrijev dodecil sulfat (NaDDS) mjeren je metodom direktne potenciometrije u ultračistoj vodi i otopinama različitih smetajućih iona (interferenata) koncetracije 1· mol/. Interferirajući ioni korišteni u eksperimentu su: klorid, jodid, fluorid, karbonat, hidrogenkarbonat, nitrat, nitrit, sulfat, sulfamat, benzoat, EDTA, ksilensulfonat, borat, hidrogenfosfat, fosfat, toluensulfonat, acetat, citrat i dodecilbenzensulfonat. Na temelju provedenih mjerenja izračunati su koeficijenti potenciometrijske selektivnosti MWCNT-TPB senzora za navedene anione.Organic substances that reduce the surface tension of liquids between two phases that do not mix with each other are called surfactants. Each surfactant is an amphiphilic compound in its structure, which means that the molecule consists of a hydrophilic and a hydrophobic part. The hydrophilic part of the surfactant molecule, which is also called the head, contains polar functional groups that can contain different charges. Given the charge found on the hydrophilic head, surfactants can be divided into four categories: anionic, cationic, nonionic, and amphoteric. The hydrophobic part of each surfactant consists of a long aliphatic hydrocarbon chain which may be straight, branched or aromatic. The hydrophilic head of the anionic surfactant releases negatively charged surfactant ions during dissociation in aqueous solutions. Surfactant analyzes are often performed using potentiometric methods based on the determination of surfactant concentration by measuring the electrochemical potential of a system consisting of two types of electrodes, indicator and reference. As an indicator electrode during the experiment, a surfactant-selective electrode was used containing a liquid membrane in which a sensor material with multiwall carbon nanotubes and tetraphenylborate (MWCNT-TPB) was embedded. The response of the MWCNT-TPB sensor to the anionic surfactant sodium dodecyl sulfate (NaDDS) was measured by direct potentiometry in ultrapure water and solutions of various interfering ions (interferences) with a concentration of 1· mol/. Interfering ions used in the experiment are: chloride, iodide, fluoride, carbonate, bicarbonate, nitrate, nitrite, sulfate, sulfamate, benzoate, EDTA, xylene sulfonate, borate, hydrogen phosphate, phosphate, toluenesulfonate, acetate, citrate and dodecylbenzene sulfonate. Based on the performed measurements, the potentiometric selectivity coefficients of MWCNT-TPB sensor for these anions were calculated
Polyphenolic profile and bioactivity of compounds presented in soy, Glicine max (L.) Merr
No full textAntioksidansi su kemijski spojevi koji usporavaju ili potpuno sprječavaju nastajanje oštećenja stanica koja su uzrokovana slobodnim radikalima. Soja (Glycine max (L.) Merr.) je mahunarka bogata antioksidansima koji štite naš organizam od kroničnih bolesti i raka. Zbog djelotvornih sastojaka, zauzima vodeće mjesto u prehrambenoj i poljoprivrednoj industriji širom svijeta. Najvažnija skupina spojeva koja je odgovorna za antioksidacijsko djelovanje su polifenoli. Flavonoidi čine najznačajniju skupinu polifenola sa strukturom difenilpropana, dijele se u 8 podskupina, a za soju vežemo prvenstveno izoflavone. Cilj ovog završnog rada je istražiti bioaktivnost spojeva u soji te analizirati polifenolni profil soje i proizvoda na bazi soje, kako bi dobili bolji uvid u potencijalni antioksidacijski učinak soje i njezin značaj za zdravlje.Antioxidants are chemical compounds that can prevent or slow damage to cells caused by free radicals. Soy (Glycine max (L.) Merr.) is a legume rich in antioxidants which protect our organism from chronic diseases and cancers. Because of its beneficial properties, soy takes a leading position in food and agricultural industry worldwide. Polyphenols are the most important group responsible for antioxidant activity. The most significant polyphenols are flavonoids with the structure of diphenylpropane, divided in 8 subgroups. Isoflavones are main flavonoids found in soy. The aim of this bachelor's thesis is to investigate the bioactivity of compounds found in soy and to analyse the polyphenolic profile of soy and soy products in order to get a better insight in the antioxidant potential of soy and its impact on the health
Solid state syntheses
No full textU modernom dobu gdje smo sve više okrenuti "zelenoj kemiji" zbog osviještenosti stanja okoliša koriste se sinteze bez toksičnih i štetnih otapala za ljudsko zdravlje i okoliš. Popularizira se sve više mehanokemijska sinteza koja ne koristi toksična organska otapala poput drugih sinteza. Cilj ovog završnog rada bio je sintetizirati trostruke perovskite Ba3Fe2WO9 i Sr3Fe2WO9 mehanokemijskom sintezom pomoću planetarnog kugličnog mlina. Dobiveni uzorci analizirani su termogravimetrijskom analizom (TGA) te rentgenskom difrakcijom na prahu (PXRD).In the modern age where we are increasingly facing green chemistry due to environmental awareness, synthesis without toxic and harmful solvents is used for shell health and the environment. More and more mechanochemical synthesis is popularized, which does not use toxic organic solvents like other synthesis. The goal of this work was to synthesize the triple perovskites and by utilization of mechanochemical synthesis using planetary ball mill. The obtained compounds were analyzed by thermogravimetric analysis (TGA) and an X-ray powder diffraction (PXRD)
Synthesis and properties of liquid crystals
No full textTekući kristali su tvari koje posjeduju svojstva tekućina i čvrstih tvari. Njihove molekule imaju uređenu strukturu jer posjeduju određenu orijentaciju i visok stupanj uređenosti kao što su molekule u kristalima, no za razliku od čvrstih tvari su fluidni te se kreću poput tekućina. Ono što ih od tekućina još razlikuje, izuzev visokog stupnja uređenosti i orijentiranih molekula, je svojstvo anizotropije koje je osnova fizikalnih svojstava tekućih kristala. Ovisno o vanjskim uvjetima u kojima se nalaze, stupnju uređenosti i orijentaciji molekula mogu biti postojani u dvije osnovne faze: termotropnoj fazi koja egzistira u točno određenom temperaturnom intervalu izvan kojega je faza tekućeg kristala narušena te liotropnoj fazi koja osim o temperaturi sustava ovisi i o njegovoj koncentraciji. Tekući kristali također grade polimerne strukture od kojih je najpoznatiji primjer poli-parafenilen tetraftalamid, komercijalnog naziva Kevlar. Najvažnija primjena tekućih kristala u današnjoj uporabi su dobro poznati LCD (engl. Liquid crystal display) zasloni koji imaju široku primjenu u raznim uređajima.Liquid crystals are materials that possess both liquid and crystalline properties. Their molecules have a very organized structure because they possess distinct orientation and a high degree of organization as molecules in crystals. But, apart from solid state, they flow as fluids. Excluding the high degree of organization, anisotropy is also a property that distinguishes liquid crystals from liquids, and that is the basis of their physical properties. Depending on external conditions, degree of organization and orientation of molecules, they can be found in two basic phases: thermotropic which is stable in a certain temperature interval and lyotropic phase which, besides temperature, depends on the concrentration of the solution. Liquid crystals can also build polymer structures and the most known is Poly(p-phenylene terephthalamide), known as Kevlar. The most important role of liquid crystals in todays life are well known LCD (liquid crystal displays), displays used in various devices
Selectivity investigation of surfactant sensors based on new quaternary ammonium salts
No full textTenzidi su sastavni dio mnogih proizvoda koji se koriste u industriji i u kućanstvu. Svakim danom se proizvode u sve većoj količini i mnogo ih završi u okolišu i tamo se nakuplja. Postoji velika potreba za brzim, jeftinim i jednostavnim načinom određivanja tenzida u proizvodima i u otpadnim vodama. U ovom radu je ispitana selektivnost pet tenzidnih senzora na bazi novih kvaternih amonijevih soli u otopinama devetnaest interferenata. Svi senzori su pokazali dobru selektivnost za anionski tenzid natrijev dodecilsulfat (NaDDS). Ispitan je i utjecaj pH u rasponu od 2 do 12 na odziv senzora, pri čemu je utvrđeno da promjena pH nema velik utjecaj. Dinamički odzivi senzora su također dobri. Uporabljivost senzora u realnim sustavima je ispitana u otopinama tri komercijalna deterdženta i rezultati su uspoređeni s rezultatima dobivenim titracijom u dvije faze.Surfactants are constituents of many products that are used in industry and in the household. Every day they are produced in increasing quantities and many end up in the environment and accumulate there. There is great need for a fast, cheap and simple way to determine surfactants in products and in wastewater. In this paper, the selectivity of five surfactant sensors based on quaternary ammonium salts was examined in solutions of nineteen interferences. All sensors showed good selectivity for anionic surfactant sodium dodecyl sulfate (NaDDS). The effect of pH in the range of 2 to 12 on the sensor response was also examined and it was found that the change in pH does not have large effect. Dynamic responses of the sensors are also good. The applicability of the sensors in real systems was tested in solutions of three commercial detergents and results were compared with results obtained by two-phases titration
Methods for thiabendazole detection
No full textTiabendazol (TBZ) je vrlo korisno antihelmintičko i fungicidno sredstvo koje je našlo široku primjenu. Kao antihelmintik, tiabendazol može djelovati na dva načina: može inhibirati enzim fumarat reduktazu ili nastanak mikrotubula tijekom mitoze. Ako se koristi kao fungicid, u gljivicama može inhibirati sustav prijenosa elektrona ili mitozu hifa. Budući da se zbog svojih učinkovitih svojstava sve učestalije koristi kao fungicid, moguće je da tiabendazol zaostaje na usjevima pa je zbog toga određena maksimalna dopuštena koncentracija pri kojoj tiabendazol ne šteti. Međutim, zbog mogućih štetnih posljedica na endokrini sustav pri višim koncentracijama, potrebno ga je određivati i pratiti u uzorcima voća, povrća, tla i vode. Tiabendazol se uspješno može odrediti raznim pektroskopskim, kromatografskim, elektroanalitičkim te biološkim i imunokemijskim metodama. Najčešće korištene metode su spektrofluorimetrija, spektroskopija površinski pojačanog Ramanovog raspršenja i tekućinska kromatografija visoke djelotvornosti.Thiabendazole (TBZ) is a very useful anthelmintic drug and fungicide that has a broad spectrum of applications. As anthelmintic, thiabendazole has two possible mechanisms of action: it can inhibit fumarate reductase or formation of microtubule during mitosis. If used as a fungicide, it can inhibit electron transfer system or mitosis of hypha in fungus. Since it has been used more often as fungicide, because of its effective properties, it is possible that thiabendazole can leave residues on crops and for this reason the maximum residue levels have been determined, at which thiabendazole is not harmful. However, due to the possible harmful effects on the endocrine system at higher levels, it should be determined and monitored in samples of fruits, vegetables, soil and water. Thiabendazole can be successfully determined by various spectroscopic, chromatographic, electroanalytical, bio- and immunochemical methods. The most commonly used methods are spectrofluorimetry, surface-enhanced Raman spectroscopy (SERS) and high-performance liquid chromatography (HPLC)