Person: YILDIRIM, AYHAN
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YILDIRIM
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AYHAN
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Publication Efficient greener methodology for the preparation of bio-based phase change materials from lipids(Taylor, 2020-11-10) Yıldırım, Ayhan; Kiraylar, Kaan; YILDIRIM, AYHAN; Kıraylar, Kaan; 0000-0003-1018-3472; 0000-0002-2328-9754; W-8924-2019; GFD-3632-2022In the present work, a new, highly efficient and simple strategy has been developed for the synthesis of long chain esters from fatty acids and fatty alcohols as phase change materials. Equivalent amounts of the selected starting compounds were taken to the esterification reaction at 110 degrees C in a solventless medium. In order to catalyze the esterification reaction, non-hygroscopic triphenylphosphine-sulfur trioxide adduct was used (0.83 mmol%) which is an easily accessible compound. The relevant reaction was completed in a very short time (2 h) and under optimized esterification conditions, excellent conversion were reached. The targeted mono ester compounds (15 examples) were obtained in good to excellent yields even after a simple crystallization step (72-99%). Additionally, a catalyst reuse investigation and study covering the scale-up production of stearyl stearate was also carried out. The triphenylphosphine-sulfur trioxide catalyzed solvent free process can compete with existing processes and proved to be a cheaper, practical and environmentally-friendly method for the esterification of fatty acids and alcohols.Publication D-fructose-derived acetonide as a green neutral organocatalyst for proficient one-pot and three-component preparation of 1,3-benzoxazine monomers(Wiley-V C H Verlag, 2020-06-23) Yıldırım, Ayhan; Göker, Mustafa; YILDIRIM, AYHAN; Göker, Mustafa; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; 0000-0002-2328-9754; W-8924-2019; JIO-8136-2023A series of 1,3-benzoxazine monomers were successfully synthesized by simple one-pot and three-component condensation of phenol, paraformaldehyde and varying types of primary aliphatic and aromatic amines in a molar ratio of 1 : 2 : 1 and in the presence of non-acidic 2,3;4,5-di-O-isopropylidene-beta-D-fructopyranose as an effective green carbohydrate based organocatalyst obtained from renewable feedstock. This multicomponent method provides a convenient fast approach for the construction of valuable 1,3-benzoxazine monomers (8 examples) with moderate to excellent yields. The chemical structures of the synthesized benzoxazines were confirmed by FTIR,H-1 NMR,C-13 NMR spectra and elemental analysis.Publication An expedient method for kinetically controlled acetonide formation from d-fructose induced by ionic liquid catalyst accompanied with sr cl 2 .6h 2 O(Springer, 2020-03-16) Yıldırım, Ayhan; YILDIRIM, AYHAN; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü; GKJ-3046-2022The present work was undertaken to ascertain whether IL-metal salt catalyzed isopropylidenation of d-fructose yield desired acetonides. For the first time, an imidazole based ionic liquid compound accompanied with strontium chloride has been identified as a suitable dual catalyst system for the chemoselective O-isopropylidenation of d-fructose with acetone. In the present protocol, mainly the kinetically controlled less stable cyclic ketal 1,2;4,5-di-O-isopropylidene-beta-d-fructopyranose is formed as an initial product with satisfactory yield and without isomerization to the thermodynamically more stable cyclic ketal 2,3;4,5-di-O-isopropylidene-beta-d-fructopyranose. Therefore, this protocol is more advantageous compared to other mineral acid catalyzed protocols that require more sensitive reaction conditions.Publication Screening of simple carbohydrates as a renewable organocatalyst for the efficient construction of 1,3-benzoxazine scaffold(Elsevier, 2021-10-05) Yıldırım, Ayhan; Kaya, Yunus; Göker, Mustafa; YILDIRIM, AYHAN; Göker, Mustafa; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; GKJ-3046-2022; EXW-1951-2022A convenient protocol for the two component preparation of 1,3-benzoxazines by using several protected and unprotected carbohydrate molecules as organocatalysts have been developed which is broadly applicable to condensation reaction between variety of Mannich bases and paraformaldehyde. This study revealed that fructose have much higher catalytic activity than the other carbohydrates and can be an alternative to metalcontaining catalysts as a green renewable organocatalyst for efficient and rapid construction of 1,3-benzoxazine skeleton. In this context, 21 benzoxazine compounds were successfully synthesized and spectral characterizations of these compounds were carried out by spectroscopic methods and elemental analysis. Furthermore, density functional theory (DFT) calculations have been performed to study the detailed mechanism of organocatalyst assisted synthesis of the benzoxazine monomers. The results obtained from these calculations showed that the more realistic reaction pathway involves formation of a phenolate based intermediate which loses a water molecule to form benzenaminium ion. Subsequently, this ion provides the formation of the corresponding benzoxazines with good yields through the intramolecular ring closure step.