Person: YILDIRIM, AYHAN
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YILDIRIM
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AYHAN
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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 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 Flexible semicrown ether-linked symmetric cationic gemini surfactants: Synthesis and evaluation as catalysts for acceleration of diastereoselective [3+2] cycloaddition reaction in reversed phase micellar media(Wiley, 2019-03-01) Öztürk, Serkan; Yıldırım, Ayhan; Gece, Gökhan; Türkdemir, Haluk; ÖZTÜRK, SERKAN; YILDIRIM, AYHAN; TÜRKDEMİR, MEHMET HALUK; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü; 0000-0002-9396-1403; 0000-0002-2328-9754; W-8924-2019; AAH-1812-2021; JJY-2268-2023Novel cationic gemini surfactants with a hydrophilic oligo-oxyethylene spacer group were synthesized and their physicochemical properties were identified. Computational studies for these compounds were also performed; molecular geometry, frontier molecular orbitals, and quantum chemical parameters were calculated using density functional theory (DFT). After exploration for catalytic activity, it was found that these surfactants can efficaciously accelerate the [3 + 2] cycloaddition reactions in reversed phase micellar media.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 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.Publication Synthesis and surface characterization studies of polyether-linked symmetric higher sulfanyl-1,3,4-oxadiazoles(Taylor, 2015-09-02) Yıldırım, Ayhan; Öztürk, Serkan; YILDIRIM, AYHAN; ÖZTÜRK, SERKAN; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü; 0000-0002-2328-9754; 0000-0002-9396-1403; W-8924-2019; AAH-1812-2021The synthesis and the characterization of a series of novel symmetric double length alkyl-chained sulfanyl-1,3,4-oxadiazoles functionalized with a polyether head group are reported. In addition, surface characterization studies were conducted on the metal surface of these synthesized compounds. The metal surfaces were characterized by contact angle measurements via the sessile-drop method, and 3D images of the metal surface were obtained using an optical profilometer. The surface studies showed that the inhibitor molecule increases the hydrophobic character and decreases the wettability of the metal surface.Publication Metallic magnesium: An efficient catalyst toward N-aryl and N-alkyl substituted amides directly from aliphatic carboxylic acids(Springer, 2015-06-01) Yıldırım, Ayhan; YILDIRIM, AYHAN; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü; 0000-0002-2328-9754; W-8924-2019An efficient and inexpensive procedure for direct conversion of aliphatic carboxylic acids into amides has been developed using anilines or aliphatic amines and Mg(0) as catalyst in toluene. The amides were obtained by single crystallization in moderate to excellent yields with high purity.Publication Synthesis of novel alkyl-sulfanyl 1,3,4-oxadiazolyl-1,3,5,7-tetraazatricyclic ammonium chloride type cationic surfactants(Wiley, 2015-03-01) Yıldırım, Ayhan; YILDIRIM, AYHAN; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü; 0000-0002-2328-9754; W-8924-2019A series of novel cationic surfactants bearing 1,3,4-oxadiazole and tetraazatricyclic ring structures were synthesized by alkyl chain elongation of 5-{10-[4-(hydroxymethyl)phenoxy]decyl}-2,3-dihydro-1,3,4-oxadiazole-2-thione with homologous series of alkyl bromides, followed by chlorination of the corresponding benzyl alcohols with thionyl chloride and quaternization of the obtained intermediates with hexamethylenetetramine.Publication Improved protocol toward 1,3,4-oxadiazole-2(3H)-thiones and scale-up synthesis in the presence of SDS as a micelle promoted catalyst(Slovensko Kemijsko Drustvo, 2015-01-01) Yıldırım, Ayhan; YILDIRIM, AYHAN; Uludağ Üniversitesi/Fen-Edebiyat FakültesiKimya Bölümü; 0000-0002-2328-9754; W-8924-2019Convenient procedure for in situ cyclization of hydrazinecarbodithioate potassium salts to 1,3,4-oxadiazole-2(3H)-thiones under normal phase micellar media catalysis promoted by sodium dodecyl sulfate (SDS) as an anionic surfactant is reported. The main advantage of this procedure is to provide shorter reaction time for the completion of cyclization; scale-up synthesis is possible and the oxadiazoles were obtained in high to excellent yields (87-100%), making the protocol an attractive alternative to the available methods.Publication Mild and efficient regioselective surfactant catalyzed deacylation of lipophilic 5-substituted 4-acyl-2-(acylamino)-δ2 1,3,4-thiadiazolines(Wiley, 2023-01-22) Yıldırım, Ayhan; YILDIRIM, AYHAN; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü; 0000-0002-2328-9754; W-8924-2019The most common transport route of biologically active compounds or drugs involves the absorption of the respective compounds across cell membranes via passive diffusion. In this context, biologically active compounds must have sufficient lipophilic character for their penetration through cell membranes. On the other hand, it is a very important task to be able to derivatize the existing compounds with effective and practical transformations to increase their biological activities. Accordingly, the free amino group in the structures of thiadiazolines can be functionalized and their biological activities can be further improved. In the present study, for the first time, several novel lipophilic 5-substituted 4-acyl-2-(acylamino)-Delta(2)-1,3,4-thiadiazolines as potential biologically active agents were synthesized and selectively deacylated with the assistance of urotropin based cationic surfactant to afford the corresponding 5-substituted 4-acyl-2-amino-Delta(2)-1,3,4-thiadiazolines with moderate to good isolated yields. The surfactant catalyzed eco-friendly method developed in this study greatly facilitated the regioselective deacylation of the thiadiazoline ring system at the N-2 position.