-
Microporous Titanosilicates as Heterogeneous Catalysts for Basic Organic Synthesis
Eleonora Butenko,
Alexey Kapustin
Issue:
Volume 10, Issue 1, March 2022
Pages:
1-4
Received:
25 November 2021
Accepted:
11 January 2022
Published:
21 January 2022
Abstract: The products of the reactions of ethylene oxide with fatty alcohols, acids and amines are of great industrial importance. They include surfactants, plasticizers and insecticides. The reactions can be generally represented as oligomerization. Interaction between ethylene oxide and alcohols can proceed in the presence of acidic as well as basic catalysts; the main distinction being in the quantitative distribution of reaction products. In the presence of basic catalysts the rate of reaction increases with the molecular weight of the products and polyaddition reaction products have a wide distribution of molecular weights. Most of the information available comes from the well investigated uses of homogeneous bases as catalysts. Research on the use of solid catalysts in this area is comparatively recent. Heterogeneous catalysts, such as the synthetic zeolites, are better known as acid catalysts. Heterogeneous catalysts with well-defined sites able to display basic properties over a wide pH range, whilst retaining insolubilty and thermal stability, are little known. This work described herein studies the basic properties of two microporous titanosilicates, known as ETS-4 and ETS-10. Determinations of surface basicity were also carried out by following the titration method. The titanosilicates were examined as catalysts for the ethoxylation of ethylene glycol. One-parameter experiments showed that the processes observed had a first-order dependence on the concentrations of ethylene oxide and catalyst. The excess of alcohol present was assumed to lead to a first-order dependence on alcohol concentration as confirmed by studies on basic. The interaction of the proton donor agent with ethylene oxide proceeds through a tri-molecular transition state. The activated C-O bond is opened by a nucleophilic attack; a similar mechanism to an SN2 nucleophilic replacement. Titanosilicates are very effective catalysts with basic sites for organic synthesis processes.
Abstract: The products of the reactions of ethylene oxide with fatty alcohols, acids and amines are of great industrial importance. They include surfactants, plasticizers and insecticides. The reactions can be generally represented as oligomerization. Interaction between ethylene oxide and alcohols can proceed in the presence of acidic as well as basic catal...
Show More
-
Analysis of the Alcohol Amine Mixtures by 1D Selective COSY
Zhang He,
Huang Guilan,
Yang Hongyu
Issue:
Volume 10, Issue 1, March 2022
Pages:
5-11
Received:
18 March 2022
Accepted:
Published:
23 March 2022
Abstract: Proton nuclear magnetic resonance (1H-NMR) is one of the most commonly used techniques for structure identification in the field of chemical warfare convention (CWC) because of its strong ability in aiding structure assignment of chemicals. However, due to the lack of separation function coupled with chromatograph, the greatest disadvantage of 1H-NMR in the analysis of environmental and biological samples is that the resonances can be easily covered or interfered. One-dimensional NMR selective excitation technology can effectively remove background interference and reveal the hidden spectral peak information. In this paper, three schedule chemicals of Chemical Weapons Convention (CWC), triethanolamine, N-methyldiethanolamine and 2-diisopropylaminoethanol, were selected as model chemicals. Homonuclear 1D COSY NMR selective excitation analysis method was established with these chemicals to solve the problem of resonances covered in 1H-NMR. Key experiment parameters of 1D COSY were optimized. The optimized experimental conditions of 1D COSY are as follows: pulse sequence is selcogp, shaped pulse is G3, relaxation delay of d1 is 4 s, the excitation width of dH 0.91 (a), 2.51 (g), 2.62 (e) and 3.44 (d) is 39.16, 35.34, 20.00 and 26.03 Hz respectively. The established 1D COSY method was used to analyze 1~10 μg/mL alcohol amine mixtures with 2 mg/mL quinuclidinol as the background interference and the LOD was 5 μg/mL. This method is simple, fast and can wipe off the interference effectively in the 1H NMR spectrum without proceeding complex sample pretreatment. 1D selective COSY reflects the more accurate position of hydrogen atom, and can be used as a reliable auxiliary technology for structural identification.
Abstract: Proton nuclear magnetic resonance (1H-NMR) is one of the most commonly used techniques for structure identification in the field of chemical warfare convention (CWC) because of its strong ability in aiding structure assignment of chemicals. However, due to the lack of separation function coupled with chromatograph, the greatest disadvantage of 1H-N...
Show More
-
Determination of the Level of Traces Essential Metals (Cu, Fe & Zn) and Toxic Metals (Pb & Cd) from Nettle Leaves (Urticadioica L.) Grown from Gozamin Woreda
Issue:
Volume 10, Issue 1, March 2022
Pages:
12-22
Received:
26 October 2021
Accepted:
15 November 2021
Published:
23 March 2022
Abstract: Nettle, Stinging Nettle (Common names) Urticadioca; Urticaurens (Scientific names) is considered by many to be a bothersome pest, but the nettle has been used since ancient times as a source of food, fiber, and medicinal preparations. They also called in commonly as nettle, weedy perennial plant of the nettle family (Urticaceae). It is known for its stinging leaves classified as eukaryote. Because they contain a true nucleus and membrane bound organelles. The accuracy of the optimized procedure was evaluated by analyzing the digest of the spiked samples with standard solution and the percentage recoveries varied from 91.2% to 109%. The concentration determined (mg/100g dry weight) were in the ranges Fe (14.583 –14.7916), Cd (0–0.4076), Cu (0.4182–2.2962), Zn (13.432–18038) and Pb (0.001–0.3083). From these Fe has high concentration from trace metals. A statistical analysis of variance (ANOVA) at 95% confidence level indicated that there is significant difference in the levels of metals among the two samples means except Cd and Pb. The results indicates that Gozamin nettle leaves are good source of essential trace metals and free from the toxic metal. All the metals concentration in this study is slightly comparable with WHO guideline of vegetables.
Abstract: Nettle, Stinging Nettle (Common names) Urticadioca; Urticaurens (Scientific names) is considered by many to be a bothersome pest, but the nettle has been used since ancient times as a source of food, fiber, and medicinal preparations. They also called in commonly as nettle, weedy perennial plant of the nettle family (Urticaceae). It is known for it...
Show More
