Molecular geometry influencing thermal-based nucleophilic reactions on silicon (111) hydride surfaces

2020 ◽  
Vol 527 ◽  
pp. 146697
Author(s):  
C.H. Lee ◽  
Y.L. Khung
10.1002/jcc.2 ◽  
1996 ◽  
Vol 17 (16) ◽  
pp. 1804-1819 ◽  
Author(s):  
Attila Kov�cs ◽  
Istv�n Kolossv�ry ◽  
G�bor I. Csonka ◽  
Istv�n Hargittai

2020 ◽  
Vol 24 (18) ◽  
pp. 2181-2191
Author(s):  
Li Wang ◽  
Ziyi Li ◽  
Jiang Liu ◽  
Jianlin Han ◽  
Hiroki Moriwaki ◽  
...  

The development of an efficient and mild synthetic methodology for the construction of bioactive fluorine-containing molecules represents one of the hot research topics in general synthetic organic chemistry. In this review, some recent progresses achieved in the development of detrifluoroacetylatively generated mono-fluorinated enolates via CC bond cleavage and their asymmetric nucleophilic reactions for assembly of chiral quaternary C-F center containing compounds.


1992 ◽  
Vol 57 (10) ◽  
pp. 2203-2207 ◽  
Author(s):  
Katarína Špirková ◽  
Štefan Stankovský

Preparation of 1-(5-substituted-2-furyl)-2-phenylsulfonyl-2-furoyl ethylenes (IIa-IId) using the Lehnert modification of Knoevenagel condensation, as well as substitution nucleophilic reactions of the 1-(5-bromo-2-furoyl)-2-phenylsulfonyl-2-furoyl derivative (IIa) with the corresponding phenolate, thiophenolate and secondary amines are described. IR, UV and 1H NMR spectra of final products are presented.


Author(s):  
Wai-Kee Li ◽  
Hung Kay Lee ◽  
Dennis Kee Pui Ng ◽  
Yu-San Cheung ◽  
Kendrew Kin Wah Mak ◽  
...  

The First Edition of this book, which appeared in 2013, serves as a problem text for Part I (Fundamentals of Chemical Bonding) and Part II (Symmetry in Chemistry) of the book Advanced Structural Inorganic Chemistry published by Oxford University Press in 2008. A Chinese edition was published by Peking University Press in August in the same year. Since then the authors have received much feedback from users and reviewers, which prompted them to prepare a Second Edition for students ranging from freshmen to senior undergraduates who aspire to attend graduate school after finishing their first degree in Chemistry. Four new chapters are added to this expanded Second Edition, which now contains over 400 problems and their solutions. The topics covered in 13 chapters follow the sequence: electronic states and configurations of atoms and molecules, introductory quantum chemistry, atomic orbitals, hybrid orbitals, molecular symmetry, molecular geometry and bonding, crystal field theory, molecular orbital theory, vibrational spectroscopy, crystal structure, transition metal chemistry, metal clusters: bonding and reactivity, and bioinorganic chemistry. The problems collected in this volume originate from examination papers and take-home assignments that have been part of the teaching program conducted by senior authors at The Chinese University of Hong Kong over nearly a half-century. Whenever appropriate, source references in the chemical literature are given for readers who wish to delve deeper into the subject. Eight Appendices and a Bibliography listing 157 reference books are provided to students and teachers who wish to look up comprehensive presentations of specific topics.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Robert Christie ◽  
Adrian Abel

Abstract Disazoacetoacetanilide pigments, more commonly known as diarylide yellows, are the most important group of yellow classical organic pigments. They were commercialized in the early 20th century many years after the introduction of the structurally related monazoacetoacetanilides (Hansa yellows). The molecules adopt the bis-ketohydrazone tautomeric form. X-ray single crystal structure investigations have provided an insight into the influence of the molecular geometry and crystal packing arrangements in the solid state on the properties of the pigments in application. The synthesis of diarylide pigments is relatively straightforward, the conditions essentially following those used for the corresponding monoazo pigments, so that the products are economically priced. In the case of these disazo pigments, suitable aromatic amines (1 mol) are bis-diazotized and the resulting bis-diazonium salts reacted with acetoacetanilide coupling components (2 mol), the two azo coupling reactions occurring at the same time. They are by far the dominant group of yellow pigments used in printing inks, well-suited for most standard process yellow inks. They were formerly important in the coloration of plastics but are no longer recommended for polymers processed above 200 °C, under which conditions toxic decomposition products are formed. Diarylide yellow pigments are characterized by high color strength, good to excellent solvent fastness, and good chemical stability, although they generally show inferior lightfastness.


Author(s):  
Nicola A. Kiernan ◽  
Andrew Manches ◽  
Michael K. Seery

Visuospatial thinking is considered crucial for understanding of three-dimensional spatial concepts in STEM disciplines. Despite their importance, little is known about the underlying cognitive processing required to spatially reason and the varied strategies students may employ to solve visuospatial problems. This study seeks to identify and describe how and when students use imagistic or analytical reasoning when making pen-on-paper predictions about molecular geometry and if particular reasoning strategies are linked to greater accuracy of responses. Student reasoning was evidenced through pen-on-paper responses generated by high attaining, high school students (N = 10) studying Valence Shell Electron Pair Repulsion (VSEPR) Theory in their final year of chemistry. Through analysis and coding of students’ open-ended paper-based responses to an introductory task, results revealed that students employed multiple reasoning strategies, including analytical heuristics and the spontaneous construction of external diagrammatic representations to predict molecular geometry. Importantly, it was observed that despite being instructed on the use of VSEPR theory to find analytical solutions, some students exhibited preference for alternative reasoning strategies drawing on prior knowledge and imagistic reasoning; showing greater accuracy with 3D diagrammatic representations than students who used the algorithmic method of instruction. This has implications for both research and practice as use of specific reasoning strategies are not readily promoted as a pedagogical approach nor are they given credit for in national examinations at school level.


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