Epoxides in vicinal diol dehydration. 7. A mechanistic characterization of the spontaneous ring opening process of epoxides in aqueous solution: kinetic and product studies

1988 ◽  
Vol 110 (19) ◽  
pp. 6492-6497 ◽  
Author(s):  
Y. Pocker ◽  
B. P. Ronald ◽  
K. W. Anderson
2021 ◽  
Vol 2 (1) ◽  
pp. 45-54
Author(s):  
Allwar Allwar ◽  
Mayla Nur Fatima ◽  
Bayu Wiyantoko

Cellulose from banana fruit bunch was used as a precursor for doping titanium oxide (TiO2) in producing of TiO2/cellulose adsorbent.  Cellulose was obtained by chemical impregnation using potassium hydroxide (KOH) and followed by the hydrothermal process at 250oC for 5 h. The mixture of TiO2 nanoparticles and cellulose was carried out into hydrothermal reactor under de-ionized water and ethanol and heated up to 200oC for 4 h in graphite furnace. Surface morphology analysis showed that the TiO2 clearly immobilized on the surface of cellulose with an increasing roughness of surface and irregular size of porosity. The development of the amorphous to the crystalline phase of TiO2/cellulose was clearly observed by the XRD. The effectiveness of TiO2/cellulose for removal of rhodamine B was investigated from different parameters of adsorption in aqueous solution. Kinetic models were well described by the pseudo-first and second-order with the best correlation coefficient (R2) attributing to the occurrence of chemisorption and physisorption mechanism.


e-Polymers ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 491-499
Author(s):  
Fukai Yang ◽  
Hao Yu ◽  
Yuyuan Deng ◽  
Xinyu Xu

Abstract In this article, five kinds of soybean oil-based polyols (polyol-E, polyol-P, polyol-I, polyol-B, and polyol-M) were prepared by ring-opening the epoxy groups in epoxidized soybean oil (ESO) with ethyl alcohol, 1-pentanol, isoamyl alcohol, p-tert-butylphenol, and 4-methoxyphenol in the presence of tetrafluoroboric acid as the catalyst. The SOPs were characterized by FTIR, 1H NMR, GPC, viscosity, and hydroxyl numbers. Compared with ESO, the retention time of SOPs is shortened, indicating that the molecular weight of SOPs is increased. The structure of different monomers can significantly affect the hydroxyl numbers of SOPs. Due to the large steric hindrance of isoamyl alcohol, p-hydroxyanisole, and p-tert-butylphenol, SOPs prepared by these three monomers often undergo further dehydration to ether reactions, which consumes the hydroxyl of polyols, thus forming dimers and multimers; therefore, the hydroxyl numbers are much lower than polyol-E and polyol-P. The viscosity of polyol-E and polyol-P is much lower than that of polyol-I, polyol-B, and polyol-M. A longer distance between the molecules and the smaller intermolecular force makes the SOPs dehydrate to ether again. This generates dimer or polymers and makes the viscosity of these SOPs larger, and the molecular weight greatly increases.


2019 ◽  
Vol 943 ◽  
pp. 95-99
Author(s):  
Li Jun Wang ◽  
Kazuo Umemura

Optical absorption spectroscopy provides evidence for individually dispersed carbon nanotubes. A common method to disperse SWCNTs into aqueous solution is to sonicate the mixture in the presence of a double-stranded DNA (dsDNA). In this paper, optical characterization of dsDNA-wrapped HiPco carbon nanotubes (dsDNA-SWCNT) was carried out using near infrared (NIR) spectroscopy and photoluminescence (PL) experiments. The findings suggest that SWCNT dispersion is very good in the environment of DNA existing. Additionally, its dispersion depends on dsDNA concentration.


2013 ◽  
Vol 4 (7) ◽  
pp. 49-54
Author(s):  
Elahaj Babiker Mohamed ◽  
Shehab Naglaa Ahmed ◽  
Ali Heyam Saad

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