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Published in Takayuki Fueno, The Transition State, 2019
Tsutomu Ikegami, Suehiro Iwata
Three stable structures and four transition states of Ar4+ are located on the ground state potential energy surface. These structures are shown in Fig. 6.1. The most stable structure is a distorted T-shape (DT, in Fig. 6.1a). There is a small barrier between two equivalent DT isomers. The transition state connecting them to each other has a symmetric T-shape (T, in Fig. 6.1c). The other local minimum is located at a linear structure (L, in Fig. 6.1b), which is separated by a transition state of TL, in Fig. 6. Id. These four structures are characterized by having a distinct trimer ion core. To give an overview of the location of these structures, the potential energy surface of Ar4+ is shown in Fig. 6.2. In this figure, the structure of the ion core is fixed at that of an isolated Ar3+ and the surface is plotted as a function of the position of the fourth atom. Note that the potential energy may be lowered if the structural relaxation of the ion core is allowed.
Base Oils
Published in Wilfried J. Bartz, Engine Oils and Automotive Lubrication, 2019
Through the series AlCl3, (C4H9)2O2, Et3Al/TiCl4, Et3Al2Cl3/TiCl4, and BF3 ⋅ H2O there is a marked trend towards a lower degree of oligomerization. The BF3 ⋅ H2O catalyst system, however, is unique in its ability to peak the oligomer at the trimer. It is a combination of this characteristic, the skeletal branching induced by this catalyst, and the consequent wide range of physical properties obtained when this catalyst is used in conjunction with 1-decene that led to the adoption of BF3/decene as the basis of manufacture by every major producer of low viscosity PAO’s. The remainder of the research presented here will deal only with BF3 catalyst systems.
Polyalphaolefins
Published in Leslie R. Rudnick, Synthetics, Mineral Oils, and Bio-Based Lubricants, 2020
The BF3 · ROH catalyst system is unique for two reasons. First, this catalyst combination produces an oligomer distribution that is markedly peaked at trimer. Figure 1.1 shows a gas chromatography (GC) trace indicating the oligomer distribution of a typical reaction product derived from 1-decene using a BF3 · n-C4H9OH catalyst combination at a reaction temperature of 30°C. The chromatogram indicates that only a relatively small amount of dimer is formed. The bulk of the product is the trimer, with only much smaller amounts of higher oligomers present.
V-shaped Schiff’s base liquid crystals based on resorcinol: synthesis and characterisation
Published in Liquid Crystals, 2020
Yuan-Yuan Quan, Duo Wang, Qing-Qing He, Ji-Wen Hu, Mei Tian, Xin-Jiao Wang, Ying-Gang Jia, Dan-Shu Yao
By introducing different polar substituents such as -OCH3, -CH3 and -Cl groups in the terminal groups, the structure modification of trimers can be realised, which will provide different materials and help to understand the relationship between molecular structure and thermal behaviour. At the same time, the effect of the length of flexible chain on the phase transition and transition temperature of V-shaped Schiff base liquid crystal molecules was studied, and the V-shaped Schiff base liquid crystal molecules were characterised by Differential Scanning Calorimeter (DSC) and POM. It was found that the polarity of substituents and the length of flexible chains play an important role in the phase transition temperature.