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471.
Sodium bicarbonate is a substance which is produced in the middle stages of the soda ash production process. In this precipitation process, carbon dioxide gas is continuously injected into the bubble column reactor which contains carbonate and bicarbonate solutions. To elucidate the key parameters affecting precipitation kinetics, an experimental study was conducted to understand nucleation and growth in conditions of industrial reactor. The composition of the solution is followed during the crystallization process by titration. Magma density is also monitored and crystal size distribution (CSD) is obtained by sieving. The method of moments was used to determine nucleation and growth rates of crystals. The nucleation and growth rate correlations for sodium bicarbonate precipitation in industrial scale were correlated by empirical power laws as B = 26.685MT0.42Δw1.31 and G = 1.381×10–4Δw1.53. The nucleation and growth rate correlations obtained in this study can be used to simulate the crystallization of sodium bicarbonate plants. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
472.
473.
Ghasem Marandi Malek Taher Maghsoodlou Nourallah Hazeri Reza Heydari Sayyed Mostafa Habibi‐Khorassani Niloufar Akbarzadeh Torbati Seyed Sajad Sajadikhah Danial Saravani Mansoureh Rakhshanipour Samira Gholamipour Faramarz Rostami‐Charati Brian W. Skelton Mohamed Makha Zeynab Zare Mojtaba Lashkari 《Heteroatom Chemistry》2011,22(5):630-639
The reaction between triphenyl or trialkyl phosphite and acetylenic esters in the presence of some heterocyclic or aromatic NH compounds such as thiazolidine‐2,4‐dione, 2‐methyl indole, 5‐bromoisatine, 3‐nitroacetanilide, saccharin, 5,5‐dimethylhydantoin, 2‐nitroaniline, 4‐nitroaniline, benzophenon hydrazine, and anthranilic acid led to the formation of phosphonato esters in high yield. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:630–639, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20725 相似文献
474.
Summary For stable processes which are Fourier transforms of processes with independent increments, we obtain a Wold decomposition, we characterize their regularity and singularity, and, in the discrete-parameter case, we derive their linear predictors. In sharp contrast with the Gaussian case, regular stable processes which are Fourier transforms of processes with independent increments are not moving averages of stable motion.This research was supported by the Air Force Office of Scientific Research Grant No. F 49620 82C0009 相似文献
475.
A facile and highly convenient base-free protocol for the chemoselective preparation of 1,2-diol mono-esters is described. In this method, the regioselective ring opening of epoxides with carboxylic acids in the presence of [bmim]Br furnishes the corresponding 1,2-diol mono-esters in excellent yields. This method is efficient for various structurally diverse epoxides and carboxylic acids and it can be efficiently applied for the scale up synthesis of 1,2-diol mono-esters in reasonable to good yields. [bmim]Br remarkably influences the reaction progress and acts as both solvent and catalyst in this protocol. 相似文献
476.
BenoÏT Rigo RGis Dolaine Samira El Ghammarti Daniel Couturier 《Journal of heterocyclic chemistry》1996,33(4):1063-1066
While methyl N-(4-nitrobenzyl)pyroglutamate can be obtained from methyl N-trimethylsilylpyroglutamate, the best way to obtain methyl N-(2-nitrobenzyl)pyroglutamate is to react 4-nitro benzyl bromide with the iminoether derived from methyl pyroglutamate. 相似文献
477.
Ali Khalafi-Nezhad Babak MokhtariMohammad Navid Soltani Rad 《Tetrahedron letters》2003,44(39):7325-7328
A very simple and efficient solvent-free procedure for the preparation of primary amides is described from carboxylic acids and urea using imidazole under microwave irradiation. Various aliphatic and aromatic primary amides were prepared in good yields by this direct amidation method. 相似文献
478.
Mitra Ghassemzadeh Samira Bahemmat Javad Malakootikhah Bernhard Neumüller Alexander Rothenberger 《无机化学与普通化学杂志》2007,633(8):1178-1182
The reactions of AMTTO = 4‐amino‐6‐methyl‐1,2,4‐triazine‐thione‐5‐one (AMTTO, 1 ) with 2‐hydroxybenzaldehyde (salicylaldehyde) and 4‐hydroxybenzaldehyde in methanol under reflux conditions led to the corresponding Schiff‐bases ( H2L1 and H2L2 ). The reaction of H2L1 with palladium acetate in ethanol and additional recrystallization from toluene gave the tetrameric complex [Pd(L)]4·2C7H8 ( 2 ). All compounds were characterized by infrared spectroscopy, elemental analyses as well as by X‐ray diffraction studies. Crystal data for H2L1 at ?80 °C: space group P21/c with a = 1285.4(1), b = 707.7(1), c = 1348.2(1) pm, β = 109.32(1)°, Z = 4, R1 = 0.0328, H2L2 at ?80 °C: space group P43212 with a = 762.5(1), b = 762.5(1), c = 4038.9(2) pm, Z = 8, R1 = 0.025 and for 2 at ?103 °C: space group C2/c with a = 2862.5(6), b = 2847.6(6), c = 1727.8(4) pm, β = 105.18(3)°, Z = 8, R1 = 0.0704. 相似文献
479.
Fernandes VT Ribeiro-Neto LM Lima SB Vieira JG Verreschi IT Kater CE 《Journal of chromatographic science》2003,41(5):251-254
21-Hydroxylase deficiency (21-OHD) is the most common form of congenital adrenal hyperplasia (CAH), followed by 11beta-hydroxylase deficiency (11beta-OHD). Diagnostic serum markers for these conditions are 17-hydroxyprogesterone (17-OHP) and 11-desoxycortisol (S), respectively. In 21-OHD, the large amounts of 17-OHP are further 11beta-hydroxylated to form 21-deoxycortisol (21-DF), making it also an excellent marker of this disease. These steroids can be measured in blood by radioimmunoassay (RIA). In this paper, we report the use of high-performance liquid chromatography (HPLC) for steroid purification, prior to RIA determinations of 21-DF, S, 17-OHP, and testosterone (T) in ether-extracted serum. The chromatographic separation is developed in a BDS-Hypersil column using water-methanol (53:47, v/v) as the mobile phase. The method is applied to 35 patients with the classic form of 21-OHD (18 females, 17 males, 5.1-14.2 years old) and 2 with 11beta-OHD (1 female, 1 male, 9.5 and 12.6 years old). Thirteen control children (5 females and 8 males, 5.2-15.2 years) are also studied. The results obtained for all measured steroids are compatible with those reported in the literature. The method is precise, and recovery is adequate. The HPLC technique proved to be of value for the purification of several steroids from single serum samples prior to RIA in patients with CAH. 相似文献
480.
A. Khalafi-Nezhad A. Zare A. Parhami M. N. Soltani Rad G. R. Nejabat 《Journal of the Iranian Chemical Society》2007,4(3):271-278
An efficient, simple and solvent-free method for highly regioselective N-alkylation of benzotriazole in the presence of SiO2, K2CO3 and tetrabutylammonium bromide (TBAB) under thermal and microwave conditions has been described. In this method, 1-alkyl benzotriazoles were obtained regioselectively in moderate to high yields and short reaction times. 相似文献