Bromination of Butyl Rubber in the Presence of Electrophilic Solvents and Oxidizing Agents

2000 ◽  
Vol 73 (2) ◽  
pp. 356-365 ◽  
Author(s):  
Gabor Kaszas
Keyword(s):  
Organic Phase ◽  
Hydrogen Bromide ◽  
Butyl Rubber ◽  
Phase System ◽  
Two Phase ◽  
Oxidizing Agents ◽  
Consecutive Reactions ◽  
Highly Uniform ◽  
Rate Controlling Step

Abstract Bromination of 1,4-isoprene units in butyl rubber proceeds by substitution leading to the formation of hydrogen bromide as byproduct. In-situ conversion of HBr back to bromine is possible by the use of oxidizing agents but the reaction is very slow and oxidation of the polymer may occur. The reaction is complex and is typically conducted in a two-phase system. It has been found that the rate-controlling step is the bromination of the 1,4-isoprene unit in the organic phase, and not the oxidation of HBr to Br2 in the water phase or the mass transfer of HBr or Br2 between phases. Increasing the electrophilicity of the organic phase dramatically increased the overall rate. A 90–95 wt % conversion of bromine was achieved in one minute. Side or consecutive reactions (oxidation of the polymer, hydrobromination of the unsaturation, rearrangement or dehydrohalogenation of the main product) could be avoided, allowing the synthesis of a highly uniform material.

scholarly journals Shrinking, Growing, and Bursting: Microfluidic Equilibrium Control of Water-in-Water Droplets

2021 ◽  
Author(s):  
Byeong-Ui Moon ◽  
Dae Kun Hwang ◽  
Scott S. H. Tsai
Keyword(s):  
Dynamic Equilibrium ◽  
Polymer Concentration ◽  
Dynamic Control ◽  
Microfluidic Channel ◽  
Continuous Phase ◽  
Phase System ◽  
Two Phase ◽  
Equilibrium Control ◽  
Tie Lines

We demonstrate the dynamic control of aqueous two phase system (ATPS) droplets in shrinking, growing, and dissolving conditions. The ATPS droplets are formed passively in a flow focusing microfluidic channel, where the dextran-rich (DEX) and polyethylene glycol-rich (PEG) solutions are introduced as disperse and continuous phases, respectively. To vary the ATPS equilibrium condition, we infuse into a secondary inlet the PEG phase from a different polymer concentration ATPS. We find that the resulting alteration of the continuous PEG phase can cause droplets to shrink or grow by approximately 45 and 30 %, respectively. This volume change is due to water exchange between the disperse DEX and continuous PEG phases, as the system tends towards new equilibria. We also develop a simple model, based on the ATPS binodal curve and tie lines, that predicts the amount of droplet shrinkage or growth, based on the change in the continuous phase PEG concentration. We observe a good agreement between our experimental results and the model. Additionally, we find that, when the continuous phase PEG concentration is reduced such that PEG and DEX phases no longer phase separate, the ATPS droplets are dissolved into the continuous phase. We apply this method to controllably release encapsulated microparticles and cells, and we find that their release occurs within 10 seconds. Our approach uses the dynamic equilibrium of ATPS to control droplet size along the microfluidic channel. By modulating the ATPS equilibrium, we are able to shrink, grow, and dissolve ATPS droplets in situ. We anticipate that this approach may find utility in many biomedical settings, for example, in drug and cell delivery and release applications.

scholarly journals Preparation, Characterization, and Optimization of an In Vitro C30 Carotenoid Pathway

2005 ◽  
Vol 71 (11) ◽  
pp. 6578-6583 ◽  
Author(s):  
Bosung Ku ◽  
Jae-Cheol Jeong ◽  
Benjamin N. Mijts ◽  
Claudia Schmidt-Dannert ◽  
Jonathan S. Dordick
Keyword(s):  
Phase System ◽  
Reaction Conditions ◽  
Two Phase ◽  
Gene Encoding ◽  
In Situ Extraction ◽  
Steady State Kinetics ◽  
Wide Range ◽  
Carotenoid Synthesis

ABSTRACT The ispA gene encoding farnesyl pyrophosphate (FPP) synthase from Escherichia coli and the crtM gene encoding 4,4′-diapophytoene (DAP) synthase from Staphylococcus aureus were overexpressed and purified for use in vitro. Steady-state kinetics for FPP synthase and DAP synthase, individually and in sequence, were determined under optimized reaction conditions. For the two-step reaction, the DAP product was unstable in aqueous buffer; however, in situ extraction using an aqueous-organic two-phase system resulted in a 100% conversion of isopentenyl pyrophosphate and dimethylallyl pyrophosphate into DAP. This aqueous-organic two-phase system is the first demonstration of an in vitro carotenoid synthesis pathway performed with in situ extraction, which enables quantitative conversions. This approach, if extended to a wide range of isoprenoid-based pathways, could lead to the synthesis of novel carotenoids and their derivatives.

scholarly journals A two-phase bromination process using tetraalkylammonium hydroxide for the practical synthesis of α-bromolactones from lactones

2021 ◽  
Vol 17 ◽  
pp. 2906-2914
Author(s):  
Yuki Yamamoto ◽  
Akihiro Tabuchi ◽  
Kazumi Hosono ◽  
Takanori Ochi ◽  
Kento Yamazaki ◽  
...  
Keyword(s):  
Large Scale ◽  
Phase System ◽  
Methyl Ethyl ◽  
Two Phase ◽  
One Pot ◽  
Mild Conditions ◽  
Substoichiometric Amount ◽  
Practical Synthesis ◽  
Industrial Use

A simple and efficient method for α-brominating lactones that affords α-bromolactones under mild conditions using tetraalkylammonium hydroxide (R4N+OH−) as a base was developed. Lactones are ring-opened with Br2 and a substoichiometric amount of PBr3, leading to good yields of the corresponding α-bromocarboxylic acids. Subsequent intramolecular cyclization over 1 h using a two-phase system (H2O/CHCl3) containing R4N+OH− afforded α-bromo lactones in good yields. This method can be applied at the 10 mmol scale using simple operations. α-Bromo-δ-valerolactone, which is extremely reactive and difficult to isolate, could be isolated and stored in a freezer for about one week using the developed method. Optimizing the solvent for environmentally friendly large-scale syntheses revealed that methyl ethyl ketone (MEK) was as effective. In addition, in situ-generated α-bromo-δ-valerolactone was directly converted into a sulfur-substituted functional lactone without difficulty by reacting it with a sulfur nucleophile in one pot without isolation. This new bromination system is expected to facilitate the industrial use of α-bromolactones as important intermediates.

Recovery of PEGylated and native lysozyme using an in situ aqueous two-phase system directly from the PEGylation reaction

2017 ◽  
Vol 92 (10) ◽  
pp. 2519-2526 ◽  
Author(s):  
Luis Alberto Mejía-Manzano ◽  
Karla Mayolo-Deloisa ◽  
Calef Sánchez-Trasviña ◽  
José González-Valdez ◽  
Mirna González-González ◽  
...  
Keyword(s):  
Phase System ◽  
Two Phase ◽  
Aqueous Two Phase System

scholarly journals A Multi-Enzyme Cascade for the Production of High-Value Aromatic Compounds

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1216
Author(s):  
Claudia Engelmann ◽  
Jens Johannsen ◽  
Thomas Waluga ◽  
Georg Fieg ◽  
Andreas Liese ◽  
...  
Keyword(s):  
Cascade Reactions ◽  
Cofactor Regeneration ◽  
Candida Boidinii ◽  
Phase System ◽  
Second Phase ◽  
Aromatic Ester ◽  
Two Phase ◽  
Enzyme Cascade

Cascade reactions are the basis of life in nature and are adapted to research and industry in an increasing manner. The focus of this study is the production of the high-value aromatic ester cinnamyl cinnamate, which can be applied in flavors and fragrances. A three-enzyme cascade was established to realize the synthesis, starting from the corresponding aldehyde with in situ cofactor regeneration in a two-phase system. After characterization of the enzymes, a screening with different organic solvents was carried out, whereby xylene was found to be the most suitable solvent for the second phase. The reaction stability of the formate dehydrogenase (FDH) from Candida boidinii is the limiting step during cofactor regeneration. However, the applied enzyme cascade showed an overall yield of 54%. After successful application on lab scale, the limitation by the FDH was overcome by immobilization of the enzymes and an optimized downstream process, transferring the cascade into a miniplant. The upscaling resulted in an increased yield for the esterification, as well as overall yields of 37%.

Chemoenzymatic Epoxidation of α-Pinene Catalyzed by Novozym 435

2013 ◽  
Vol 634-638 ◽  
pp. 896-900 ◽  
Author(s):  
Cheng Zou ◽  
You Yan Liu ◽  
Yi Ming Qin ◽  
Ai Xing Tang ◽  
Li Na Lan
Keyword(s):  
Hydrogen Peroxide ◽  
Organic Phase ◽  
Octanoic Acid ◽  
Novozym 435 ◽  
Phase System ◽  
In Situ Oxidation ◽  
Novozyme 435 ◽  
Three Phase ◽  
Novozym 435 Lipase

The synthesis of α-pinene oxide mediated by Novozym 435 (lipase from Candida antarctica) in a three-phase system was studied in this work. Novozyme 435 catalysed the formation of peroxyoctanoic acid directly from octanoic acid and hydrogen peroxide, which was then applied for in situ oxidation of α-pinene. The highest conversion of a-pinene (approximately 80%) was obtained when the reaction was performed at 30°C and initial hydrogen peroxide concentration in the water phase was set to be 30%. The parameters affecting the lipase activity were also investigated，where the peracid generated in organic phase was obvserved to greatly inactivate the enzyme compared to other components in the organic phase.

scholarly journals ω-Transaminase-Mediated Asymmetric Synthesis of (S)-1-(4-Trifluoromethylphenyl)Ethylamine

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 307
Author(s):  
Carlos J. C. Rodrigues ◽  
Manuel Ferrer ◽  
Carla C. C. R. de Carvalho
Keyword(s):  
Enzyme Activity ◽  
Organic Phase ◽  
Process Development ◽  
Enzyme Reaction ◽  
Building Blocks ◽  
Inhibitory Effect ◽  
Chiral Amines ◽  
Phase System ◽  
Two Phase ◽  
Chiral Amine

The pivotal role played by ω-transaminases (ω-TAs) in the synthesis of chiral amines used as building blocks for drugs and pharmaceuticals is widely recognized. However, chiral bulky amines are challenging to produce. Herein, a ω-TA (TR8) from a marine bacterium was used to synthesize a fluorine chiral amine from a bulky ketone. An analysis of the reaction conditions for process development showed that isopropylamine concentrations above 75 mM had an inhibitory effect on the enzyme. Five different organic solvents were investigated as co-solvents for the ketone (the amine acceptor), among which 25–30% (v/v) dimethyl sulfoxide (DMSO) produced the highest enzyme activity. The reaction reached equilibrium after 18 h at 30% of conversion. An in situ product removal (ISPR) approach using an aqueous organic two-phase system was tested to mitigate product inhibition. However, the enzyme activity initially decreased because the ketone substrate preferentially partitioned into the organic phase, n-hexadecane. Consequently, DMSO was added to the system to increase substrate mass transfer without affecting the ability of the organic phase to prevent inhibition of the enzyme activity by the product. Thus, the enzyme reaction was maintained, and the product amount was increased for a 62 h reaction time. The investigated ω-TA can be used in the bioconversion of bulky ketones to chiral amines for future bioprocess applications.

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