HYDROXYMETHYL PHOSPHORUS DERIVATIVES FROM TETRAKIS(HYDROXYMETHYL) PHOSPHONIUM CHLORIDE. REACTION WITH LEAD CARBONATE AND OXIDE

1963 ◽  
Vol 41 (4) ◽  
pp. 821-825 ◽  
Author(s):  
N. Filipescu ◽  
L. M. Kindley ◽  
H. E. Podall ◽  
F. A. Serafin
Keyword(s):  
Phosphine Oxide ◽  
Lead Oxide ◽  
Elevated Temperatures ◽  
Azeotropic Distillation ◽  
No Oxidation ◽  
Reaction Conditions ◽  
Lead Carbonate ◽  
Propyl Alcohol ◽  
Phosphonium Chloride ◽  
Reaction Proceeds

A novel and convenient method has been developed for the preparation of tris(hydroxy-methyl) phosphine oxide (THPO) from tetrakis (hydroxymethyl) phosphonium chloride (THPC). The method consists essentially of oxidative deformylation of THPC with lead carbonate in n-propyl alcohol. The reaction is facilitated by azeotropic distillation of di-n-propylformal and n -propyl alcohol.The reaction of THPC with lead carbonate as well as with lead oxide has been studied in detail in aqueous solution and in n-propyl alcohol. The reaction proceeds via the initial formation of tetrakis(hydroxymethyl) phosphonium hydroxide (THPOH) followed by deformylation to tris (hydroxymethyl) phosphine (THP). THP then undergoes oxidation by air as well as by lead carbonate or oxide to THPO. If air is bubbled through the mixture at elevated temperatures, atmospheric oxidation predominates with little or no oxidation by the lead compound.Depending upon the reaction conditions, a phosphonium hydroxide, a phosphine, or a phosphine oxide are products of the reaction of tetrakis(hydoxymethyl) phosphonium chloride with lead carbonate or oxide.

scholarly journals The Eschenmoser coupling reaction under continuous-flow conditions

2011 ◽  
Vol 7 ◽  
pp. 1164-1172 ◽  
Author(s):  
Sukhdeep Singh ◽  
J Michael Köhler ◽  
Andreas Schober ◽  
G Alexander Groß
Keyword(s):  
Continuous Flow ◽  
Elevated Temperatures ◽  
Reaction Times ◽  
Coupling Reaction ◽  
Flow Chemistry ◽  
Flow Conditions ◽  
Reaction Conditions ◽  
Bond Forming ◽  
Carbon Carbon Bond ◽  
Reaction Proceeds

The Eschenmoser coupling is a useful carbon–carbon bond forming reaction which has been used in various different synthesis strategies. The reaction proceeds smoothly if S-alkylated ternary thioamides or thiolactames are used. In the case of S-alkylated secondary thioamides or thiolactames, the Eschenmoser coupling needs prolonged reaction times and elevated temperatures to deliver valuable yields. We have used a flow chemistry system to promote the Eschenmoser coupling under enhanced reaction conditions in order to convert the demanding precursors such as S-alkylated secondary thioamides and thiolactames in an efficient way. Under pressurized reaction conditions at about 220 °C, the desired Eschenmoser coupling products were obtained within 70 s residence time. The reaction kinetics was investigated and 15 examples of different building block combinations are given.

scholarly journals N-Methyl-D-Glucoseimine Synthesis Reaction Thermodynamic Properties Calculation

2020 ◽  
Vol 6 (11) ◽  
pp. 40-46
Author(s):  
S. Mikhailov ◽  
R. Brovko ◽  
S. Mushinskii ◽  
M. Sulman
Keyword(s):  
Elevated Temperatures ◽  
Equilibrium Constants ◽  
Thermodynamic Calculations ◽  
Process Conditions ◽  
Reaction Conditions ◽  
Formation Reaction ◽  
Reaction Proceeds ◽  
Energy Equilibrium ◽  
Reversible Formation ◽  
Pharmaceutical Practice

The presented article is devoted to thermodynamic calculations of the N-methyl-D-glucosimine reversible formation reaction, an intermediate product for N-methyl-D-glucosamine synthesis, which is widely used in pharmaceutical practice as a ballast or counterion that improves the bioavailability of the main active substance. N-methyl-D-glucosimine is synthesized as a result of the interaction of D-glucose with methylamine in organic solvents, the reaction is reversible, and the yield of the target product depends entirely on the reaction conditions. The use of thermodynamic calculations makes it possible to evaluate the influence of the chemical process conditions on the yield of target products, which in turn contributes to a deeper understanding of the chemical reactions mechanisms. In chemical equilibrium, direct and reverse reactions proceed at equal rates, while the concentrations of products and reagents remain constant. When the reaction proceeds in a closed system, after a certain time, a state of equilibrium occurs, while the reaction does not proceed with a complete transformation of the reagents. This article presents the results of thermodynamic calculations of the reaction for the synthesis of N-methyl-D-glucosimine by the Van Kravlen – Cheremnov method. The Gibbs energy, equilibrium constants, and D-glucose conversion were calculated as activity function of reacting substances. It was shown that an increase in the temperature of the reaction mixture from 20 to 160 °C promotes an increase in the conversion of D-glucose from 3 to 32%, and therefore it is possible to recommend carrying out this reaction at elevated temperatures.

scholarly journals Synthesis of propylene carbonate from urea and 1,2-propylene glycol over metal carbonates

2011 ◽  
Vol 17 (3) ◽  
pp. 323-331 ◽  
Author(s):  
Jiancheng Zhou ◽  
Wu Dongfang ◽  
Birong Zhang ◽  
Yali Guo
Keyword(s):  
Reaction Time ◽  
Propylene Glycol ◽  
Propylene Carbonate ◽  
Reaction Temperature ◽  
Reaction Conditions ◽  
Lead Carbonate ◽  
Synthetic Process ◽  
Metal Carbonates ◽  
Optimal Reaction ◽  
Mixed Carbonate

A series of single-metal carbonates and Pb-Zn mixed-metal carbonates were prepared as catalysts for alcoholysis of urea with 1,2-propylene glycol (PG) for the synthesis of propylene carbonate (PC). The mixed carbonates all show much better catalytic activities than the single carbonates, arising from a strong synergistic effect between the two crystalline phases, hydrozincite and lead carbonate. The mixed carbonate with Pb/Zn=1:2 gives the highest yield of PC, followed by the mixed carbonate with Pb/Zn=1:3. Furthermore, Taguchi method was used to optimize the synthetic process for improving the yield of PC. It is shown that the reaction temperature is the most significant factor affecting the yield of PC, followed by the reaction time, and that the optimal reaction conditions are the reaction time at 5 hours, the reaction temperature at 180 oC and the catalyst amount at 1.8 wt%, resulting in the highest PC yield of 96.3%.

The Study of the Melting of Waelz Oxide with an Increase in the Temperature of the Calcination Process

2021 ◽  
Vol 316 ◽  
pp. 705-710
Author(s):  
A.G. Ryazanov ◽  
A.V. Senin ◽  
V.D. Nasonov
Keyword(s):  
Partial Melting ◽  
Gas Phase ◽  
Lead Oxide ◽  
Elevated Temperatures ◽  
Lead Sulfate ◽  
Raw Material ◽  
Chemical Transformations ◽  
Calcination Process ◽  
Waelz Oxide ◽  
Negative Effect

Waelz-oxide is a raw material for the production of metallic zinc. Waelz-oxide contains impurities of zinc and lead chlorides and fluorides. Halides have a negative effect on the process of zinc electrolysis. Halides have a relatively low boiling point; therefore, they are removed into the gas phase by calcining Waelz-oxide at 800–850 °С. To intensify the process, calcination is sometimes carried out at elevated temperatures of 1100–1250 °С. However, an increase in temperature leads to partial melting and granulation of the calcined product. In the present work, the chemical and phase composition of the initial and calcined Waelz-oxide was studied. Thermodynamic modeling of phase and chemical transformations of Waelz-oxide components during heating has been performed. Experiments on calcination of Waelz-oxide in laboratory conditions at temperatures of 600–1250 °C were carried out. It was found that partial melting and granulation of Waelz-oxide is the result of the formation of fusible eutectics containing lead oxide. Lead oxide is formed as a result of decomposition of lead sulfate when heated above 1100 °C. A similar effect is not observed at a standard calcination temperature of 850 °C.

scholarly journals Preparation of Glucosamine Hydrochloride from Indigenous Shrimp Processing Waste

1970 ◽  
Vol 46 (3) ◽  
pp. 375-378 ◽  
Author(s):  
MM Islam ◽  
SM Masum ◽  
MM Rahman ◽  
AA Shaikh
Keyword(s):  
Maximum Yield ◽  
Therapeutic Activity ◽  
Processing Waste ◽  
Reaction Conditions ◽  
Glucosamine Hydrochloride ◽  
Glycoside Linkage ◽  
Shrimp Shell ◽  
Reaction Proceeds ◽  
Ft Ir ◽  
Hydrolysis Of

The present investigation described the effective preparation of glucosamine hydrochloride (GluHCl) from chitin which was extracted from indigenous shrimp shell. GluHCl has attracted much attention owing to its therapeutic activity in osteoarthritis and widely used dietary supplement. The key step involved was extraction of chitin from shrimp skeleton and then hydrolysis of chitin by concentrated hydrochloric acid. The reaction proceeds via break down of glycoside linkage. Structural analysis was carried out by melting point, TLC, FT-IR, elemental analysis and all the data were compared with that of standard GluHCl. The elemental (C, 32.75; H, 6.51; N, 6.20) analysis is good concord with the calculated value (C, 33.42; H, 6.54; N, 6.50). Absence of v max at 1726 cm-1 indicates that GluHCl is a deacetylated product of chitin. The yields of the product mainly depend on reaction conditions. Maximum yield (63.5%) was obtained when chitin was hydrolyzed with concentrated HCl for 1.30 h. Key words: Shrimp shell; Chitin, Acid hydrolysis; Glucosamine hydrochloride Osteoarthritis. DOI: http://dx.doi.org/10.3329/bjsir.v46i3.9046 BJSIR 2011; 46(3): 375-378

scholarly journals Intermolecular 3+3 Ring Expansion of Aziridines to Dehydropiperidines through the Intermediacy of Aziridinium Ylides

2019 ◽  
Author(s):  
Jennifer Schomaker ◽  
Josephine Eshon ◽  
Kate A. Nicastri ◽  
Steven C. Schmid ◽  
William T. Raskopf ◽  
...  
Keyword(s):  
Natural Product ◽  
Functional Group ◽  
Ring Expansion ◽  
Sigmatropic Rearrangement ◽  
Reactive Intermediate ◽  
Mechanistic Studies ◽  
Reaction Conditions ◽  
Complex Molecules ◽  
Form Complex ◽  
Reaction Proceeds

Bicyclic aziridines undergo formal [3+3] ring expansion reactions when exposed to rhodium-bound vinyl carbenes to form complex dehydropiperidines in a highly stereocontrolled rearrangement. Mechanistic studies and DFT computations indicate the reaction proceeds through the formation of a vinyl aziridinium ylide; this reactive intermediate undergoes a concerted, asynchronous, pseudo-[1,4]- sigmatropic rearrangement to directly furnish the heterocyclic products with net retention at the new C-C bond. In combination with an asymmetric silver-catalyzed aziridination developed in our group, this method quickly delivers enantioenriched scaffolds with up to three contiguous stereocenters. The mild reaction conditions, functional group tolerance, and high stereochemical retention of this method are especially well-suited for appending piperidine motifs to natural product and complex molecules. Ultimately, our work establishes the value of underutilized aziridinium ylides as key intermediates in strategies to convert small, strained rings to larger N-heterocycles.

Diversity-Oriented Synthesis via Catalyst-Free Addition of Ketones to [e]-Fused 1H-Pyrrole-2,3-diones

Synthesis ◽  
2018 ◽  
Vol 50 (24) ◽  
pp. 4897-4904 ◽  
Author(s):  
Ekaterina Stepanova ◽  
Andrey Maslivets ◽  
Svetlana Kasatkina ◽  
Maksim Dmitriev
Keyword(s):  
Intramolecular Cyclization ◽  
Aromatic Hydrocarbons ◽  
Michael Addition ◽  
Aldol Reaction ◽  
Synthetic Approach ◽  
Reaction Conditions ◽  
Diversity Oriented Synthesis ◽  
Catalyst Free ◽  
Solvent Free Conditions ◽  
Reaction Proceeds

A facile synthetic approach towards two distinct pyrrole-based heterocyclic scaffolds has been developed by the interaction of 1H-pyrrole-2,3-diones fused at the [e]-side to a 1,4-benzoxazin-2-one or quinoxalin-2(1H)-one moiety with ketones. The described interaction proceeds either as an aldol reaction or as a Michael addition/intramolecular cyclization depending on the reaction conditions. The disclosed aldol reaction proceeds with good diastereoselectivity under catalyst-free conditions when the reaction is carried out in aromatic hydrocarbons. Products of the cascade Michael addition/intramolecular cyclization reaction are predominantly formed under catalyst-free and solvent-free conditions. The proposed strategy provides facile access to pharmaceutically interesting pyrrole-based polyheterocycles.

Mechanical Properties and Oxidation Behavior of Si3N4/BN Laminated Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 1869-1872
Author(s):  
Cui Wei Li ◽  
Chang An Wang ◽  
Yong Huang
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Boron Nitride ◽  
Oxidation Behavior ◽  
Elevated Temperatures ◽  
Testing Procedure ◽  
No Oxidation ◽  
Temperature Oxidation ◽  
High Temperature Oxidation Behavior

Laminated ceramics with high mechanical properties were fabricated in the Si3N4/BN system. The mechanical properties at elevated temperatures were tested, and the oxidation behavior during tested procedure was studied at the same time. The flexure strength of the Si3N4/BN laminated ceramics changed a little below 1000°C. The displacement-load curves appeared non-linear characteristic even at high temperature. During testing procedure at high temperature, oxidation behavior of silicon nitride and silicon carbide happened, and no oxidation product of boron nitride was found. The silicon nitride layers were oxidized to form a protective silicate scale, which prevented oxidation of the boron nitride interlayers. The stability of boron nitride was beneficial to the boron nitride interlayer to partition the silicon nitride matrix layers at high temperature.

Lead recovery from spent lead acid battery paste by hydrometallurgical conversion and thermal degradation

2019 ◽  
Vol 38 (3) ◽  
pp. 263-270
Author(s):  
Wenke Liu ◽  
Qingwei Qin ◽  
Dengqi Li ◽  
Guangqiang Li ◽  
Yinjie Cen ◽  
...  
Keyword(s):  
Thermal Degradation ◽  
Lead Oxide ◽  
Lead Dioxide ◽  
Scanning Calorimetry ◽  
Lead Carbonate ◽  
Lead Acid Batteries ◽  
Novel Approach ◽  
Lead Recovery ◽  
Main Component ◽  
Lead Acid

Spent lead paste is the main component in lead-acid batteries reaching end of life. It contains about 55% lead sulphate and 35% lead dioxide, as well as minor amounts of lead oxide. It is necessary to recycle spent lead paste with minimal pollution and low energy consumption instead of the conventional smelting method. In this study, a novel approach involving hydrometallurgical desulphurisation and thermal degradation is developed to recover lead as PbO products from spent lead acid batteries. First, the desulphurisation effects and phase compositions of products with different transforming agents were compared, and the optimum conditions using (NH4)2CO3 as a transforming agent were determined. And then, the thermal degradation processes of both precursors lead carbonate and lead dioxide were investigated to prepare α-PbO, Pb3O4, and β-PbO products in argon and air atmospheres, respectively. Both the desulphurisation precursors and the calcination products were characterised by thermogravimetry and differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. The results showed that the lead oxide products were prepared, including α-PbO at 450°C in argon, Pb3O4 and β-PbO at 480°C and 620°C in air, respectively.

Copper(II)-Promoted Oxidation/[3+2]Cycloaddition/Aromatization Cascade: Efficient Synthesis of Tetrasubstituted NH-Pyrrole from Chalcones and Iminodiacetates

Synlett ◽  
2019 ◽  
Vol 30 (12) ◽  
pp. 1442-1446 ◽  
Author(s):  
Zhang-qi Lin ◽  
Chao-dong Li ◽  
Zi-chun Zhou ◽  
Shuai Xue ◽  
Jian-rong Gao ◽  
...  
Keyword(s):  
Efficient Method ◽  
Cascade Reaction ◽  
Oxidative Cyclization ◽  
Efficient Synthesis ◽  
Reaction Conditions ◽  
Highly Efficient ◽  
Wide Range ◽  
Reaction Proceeds

A simple and highly efficient method for the preparation of tetrasubstituted NH-pyrrole from a wide range of chalcones and diethyl iminodiacetates via a Cu(OAc)2-promoted oxidation/[3+2]cycloaddition/aromatization cascade reaction has been developed. This reaction proceeds through dehydrogenations, deamination, and oxidative cyclization, affording the corresponding products in good to excellent yields. This convenient methodology for constructing tetrasubstituted NH-pyrroles has several advantages over existing methods, such as the use of easily accessible chalcones and readily available diethyl iminodiacetates, and mild reaction conditions. A wide range of substrates are tolerated.

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