Strukturna karakterizacija i analitička primjena aromatskih hidrazona izvedenih iz nikotinohidrazida

doctoral thesis

• Title (english): Structural characterization and analytical application of aromatic hydrazones derived from nicotinic acid hydrazide
• Author: Tomislav Benković
• Mentor: Nives Galić (mentor)
• Committee member: Snežana Miljanić (predsjednik povjerenstva)
• Committee member: Ana Budimir (član povjerenstva)
• Committee member: Vesna Petrović-Peroković (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Chemistry); Zagreb
• Defense date and country: 2018-12-18, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry
• Universal decimal classification (UDC): 54 - Chemistry. Crystallography. Mineralogy

Abstract

Proučavano je dvanaest aromatskih hidrazona izvedenih iz nikotinohidrazida i različito supstituiranih benzaldehida, odnosno fenil-metil-ketona. Identifikacija i karakterizacija spojeva provedena je spektrometrijom masa i spektroskopskim metodama (NMR, UV-Vis i spektrofluorimetrija). Spektrometrijom masa razlikovani su metoksi derivati uslijed različitog pomaka keto-enolne tautomerne ravnoteže u plinskoj fazi. Dihidroksi- i klor- derivati razlikovani su na temelju "ortho efekta". Hidrazoni se u otopini nalaze u najstabilnijem enoliminskom obliku, osim nitro derivata koji u dimetilsulfoksidu podliježe deprotonaciji, E/Z izomeriji i keto-enolnoj tautomeriji. Za klor- i nitro- derivate uočena je fluorescencija u lužnatom. Spektrofotometrijskim titracijama određene su konstante protoniranja svih spojeva u sustavu metanol/voda 1/1. Vrijednosti pKa smanjuju se povećanjem elektron-odvlačećeg djelovanja supstituenta na salicilidenskom prstenu. U istom sustavu otapala praćena je hidroliza svih spojeva. U kiselim otopinama hidrolizu ubrzavaju elektron-donirajući supstituenti u para, a u lužnatom elektron-odvlačeći supstituenti u meta položaju u odnosu na dvostruku vezu C=N. Metoksi-derivati primijenjeni su kao ekstrakcijski reagensi za željezo(III). Razrađena je spektrofotometrijska metoda određivanja željeza spojem N'-(2-hidroksi-3-metoksifenilmetiliden)-3-piridinkarbohidrazidom.

Abstract (english)

Twelve aromatic hydrazones, derived from nicotinic acid hydrazide and differently substituted benzaldehydes or phenyl-methyl-ketone were studied. Identification and characterization of compounds were performed by mass spectrometry and spectroscopic methods (NMR, UV-Vis, and spectrofluorescence). Methoxy derivatives were distinguished by mass spectrometry duo to keto-enol tautomeric interconversion in gas phase. Dihydroxy and chloro derivatives were distinguished by "ortho effect". In solution, hydrazones were present in most stable enolimino form, apart from nitro derivative, which was subjected to deprotonation, E/Z isomerization and keto-enol tautomeric interconversion. Fluorescence was observed for chloro and nitro derivatives in basic media. Protonation constants for all compounds were determined in methanol/water 1/1 system by spectrophotometric titrations. The pKa values were lowered by electron-withdrawing substituent on the salicylidene ring. The hydrolisys of all compounds was studied in the same system. In acidic solutions the hydrolysis was faster due to electron-donor substituent in para, and in basic media by electron-withdrawing groups in meta position to the C=N double bond. Methoxy derivatives were used as extracting agents for iron(III). The spectrophotometric method for iron(III) determination by N'-(2-hydroxy-3-methoxyphenylmethylidene)-3-pyridinecarbohydrazide was developed.

• Keywords: aroilhidrazoni; hidroliza; izomerizacija; kompleksiranje; konstante protoniranja; strukturna karakterizacija; tautomerija
• Keywords (english): aroylhydrazones; complexation; hydrolysis; isomerization; protonation constants; structural characterization; tautomerism
• Language: croatian
• URN:NBN: urn:nbn:hr:217:573792
• Study programme: Title: Doctoral study in chemistry; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje kemija (doktor/doktorica znanosti, područje prirodnih znanosti, polje kemija)
• Type of resource: Text
• Extent: 154 str. ; 30 cm
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-01-09 14:08:30