Priprava in karakterizacija kokristalov 4-nitropiridin-N-oksida z derivati benzojske kisline

Kužnik, Karmen (author), Golobič, Amalija (mentor)

Namen diplomskega dela je bil pripraviti kokristale piridin-N-oksida z benzojsko kislino in kokristale 4-nitro-piridin-N-oksida z naslednjimi derivati benzojske kisline: salicilno kislino, 2,6-dihidroksibenzojsko kislino in 2-fluorobenzojsko kislino. Sinteze smo izvajali s kristalizacijo. Reaktanta smo najprej zmleli in jima dodali topilo. Tako zmes smo segrevali ob mešanju do 70 °C, zatem pa poskusili izločiti kokristale z ohlajevanjem in počasnim odparevanjem topila. Dobljene produkte smo analizirali oziroma karakterizirali s pomočjo rentgenske difrakcije ter v nekaterih primerih tudi IR spektroskopije in CHN analize. Po postopku iz literature smo uspeli ponoviti sintezo kokristalov 4-nitropiridin-N-oksida in salicilne kisline (kokristal 1). Enak postopek smo uporabili za pripravo novih kokristalov, ki v literaturi še niso bili opisani, to je kokristalov 4-nitropiridin-N-oksida in 2,6-dihidroksibenzojske kisline (kokristal 2). Z rentgensko difrakcijo na monokristalu smo določili njihovo kristalno strukturo. Ugotovili smo, da so molekule kisline preko karboksilne skupine povezane z O atomom iz nitrozo skupine 4-nitro-piridin-N-oksida z močno vodikovo vezjo, kar je verjetno gonilna sila za nastanek teh kokristalov. Produkt smo karakterizirali tudi s praškovno difrakcijo, IR spektroskopijo in CHN analizo. Rezultati teh analiz so se ujemali z ugotovljeno kristalno strukturo. Na enak način smo želeli pripraviti kokristale 4-nitro-piridin-N-oksida z 2-fluorobenzojsko kislino, smo namesto kokristalov dobili le zmes kristalov izhodnih snovi. Poskusi priprave kokristalov piridin-N-oksida z benzojsko kislino so bili neuspešni zaradi velike higroskopnosti piridin-N-oksida in vlage v zraku. Zaradi tega se piridin-N-oksid ni izločil ne sam ne v obliki kokristalov.

• Language: Slovenian
• Keywords: kokristal, nitropiridin-N-oksid, hidroksi-benzojska kislina, rentgenska difrakcija, struktura
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2019
• PID: 20.500.12556/RUL-113242
• COBISS.SI-ID: 1538508227
• Publication date in RUL: 16.12.2019

KUŽNIK, Karmen, 2019, Priprava in karakterizacija kokristalov 4-nitropiridin-N-oksida z derivati benzojske kisline [online]. Bachelor’s thesis. [Accessed 14 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=113242

Secondary language

• Language: English
• Title: The preparation and characterization of co-crystals of 4-nitropyridine N-oxide with derivatives of benzoic acid

Abstract

The goal of this thesis was to produce co-crystals of pyridine-N-oxide with benzoic acid and co-crystals of 4-nitropyridine N-oxide with the following derivatives of benzoic acid: salicylic acid, 2,6-dihydroxybenzoic acid and 2-fluoro benzoic acid. Syntheses were performed with crystallization. The reactants were at first grinded and after that solvent was added. This mixture was then heated until 70 °C while also mixed. After that we tried to grow co-crystals by cooling and slow evaporation of the solvent. These products were analysed by X-ray diffraction and in some cases with IR spectroscopy and CHN analysis. According to the literature data, we managed to repeat the synthesis of co-crystals of 4-nitropyridine N-oxide and salicylic acid (co-crystal 1). By the same synthetic procedure (using 2,6-dihydroxybenzoic instead of salicylic acid) new co-crystals, which haven’t been reported in the literature yet, that is co-crystals of 4-nitropyridine N-oxide and 2,6-dihydroxybenzoic acid (co-crystal 2), were prepared. Their crystal structure was determined by X-ray single crystal diffraction. In co-crystals 2 acid molecules are bonded via carboxylic group to O atom of nitroso group of 4-nitropyridine N-oxide with a strong hydrogen bond, which is probably the main driving force for the existence of these co-crystals. The product was characterized also by X-ray powder diffraction, IR spectroscopy and CHN analysis. The results of these analyses were in the agreement with the results of structure analysis. Other syntheses were not successful. When we wanted to produce co-crystals of 4-nitropyridine N-oxide with 2-fluoro benzoic acid, we got a mixture of crystals of starting solids instead of co-crystals. The experiments of producing of co-crystals of pyridine-N-oxide with benzoic acid were also unsuccessful because of high hygroscopicity of pyridine-N-oxide and air’s moisture. That was the reason why pyridine-N-oxide did not percipitate neither itself nor in the form of co-crystals.

• Keywords: co-crystal, nitropyridine N-oxide, hydroxybenzoic acid, X-ray diffraction analysis, structure