scholarly journals Increased efficiency in biomimetic Lewis acid–base pair catalyzed monoacylation of diols by acyl phosphate monoesters

FACETS ◽  
2017 ◽  
Vol 2 (2) ◽  
pp. 682-689 ◽  
Author(s):  
Yuyang Li ◽  
Ronald Kluger
Keyword(s):  
Metal Ion ◽  
Acid Base ◽  
Reaction Conditions ◽  
Lanthanum Ions ◽  
Lead Salts ◽  
Phosphate Monoesters ◽  
Zinc Salts ◽  
Acyl Phosphate ◽  
Hydrolysis Of ◽  
By Products

Acyl phosphate monoesters are biomimetic acylation reagents that require coordination to metal ions to react with cis-diol substrates in water. With lanthanide catalysts, outcomes are compromised by (1) the competitive lanthanide-promoted hydrolysis of the acyl phosphate reagents as well as by (2) the high affinity of lanthanum ions for the phosphate monoester by-product. Based on analysis of the mechanism of the process, optimizing reaction conditions can selectively inhibit the lanthanum-promoted hydrolysis of acyl phosphate monoesters. Furthermore, using zinc salts and lead salts in place of lanthanides enhances the reactivity of the reactants and causes less complexation of the metal ion with the by-products.

scholarly journals Tandem Triphosgene-Assisted Metal-Free One-pot Preparation of Nitriles and Amides from Aldehydes and Ketones

2021 ◽  
Author(s):  
Jianguo liu ◽  
Xiu-Zhi Wei ◽  
Longlong Ma
Keyword(s):  
Metal Catalysts ◽  
Organic Base ◽  
Reaction Conditions ◽  
One Pot ◽  
Metal Free ◽  
Aldehydes And Ketones ◽  
Ester Linkage ◽  
Hydrolysis Of ◽  
By Products

Here we report a facile and efficient triphosgene-assisted one-pot conversion of aldehydes/ketones into nitriles/amides. The triphosgene, a kind of phosgene alternative, containing both ester linkage and chloromethyl units, easily reacts with oximes for the preparation of nitriles/amides. However, the reaction of oximes with triphosgene can’t fully convert corresponding nitriles/amides due to hydrolysis of oximes to aldehydes or ketones. Our protocol tandem proceeds smoothly without the use of organic base and metal catalysts. Diverse functionalized aromatic, aliphatic, and allylic aldehydes/ketones incorporating biomass-derived platform compounds were successfully converted to nitriles and amides in excellent yields. Compared to step-by-step reaction, this tandem strategy is characterized by multi-step reaction in one pot, mild reaction conditions, and fewer by-products.

Metal-Catalyzed Site-Selective Monoacylation of Diols in Aqueous Media

Synthesis ◽  
2019 ◽  
Vol 51 (20) ◽  
pp. 3784-3791
Author(s):  
Yuyang Li ◽  
Ronald Kluger
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Aqueous Media ◽  
Water Soluble ◽  
Solvent Mixtures ◽  
Phosphate Monoesters ◽  
Stable Reagent ◽  
Metal Catalyzed ◽  
Site Selective ◽  
Acyl Phosphate

Site-selective reactions of water-soluble biomolecules are being developed to produce efficient conversions in water and water­/solvent mixtures. This review focuses on the use of designs based on bis-bidentate chelation of large metal ions by diols to be acylated by a co-chelated water-stable reagent. Topics discussed include: 1. The preparation and properties of water-stable acyl phosphate monoesters and their reactions with diol-chelated metal ions. 2. Site-selective monoaminoacylation of 3′-terminal diols of RNA and their applications in protein engineering. 3. Site-selective monoacylation of sugars with acyl phosphate monoesters associated with metal ions, including lanthanum and lead. The combination of metal ion, 1,2-diol, and acyl phosphate monoester produces site-selective reactions in aqueous media­ that can produce a general approach to site-selective mono-(amino)acylation in RNA and carbohydrates.1 Introduction2 Synthetic Aminoacylation of tRNA3 Activated Amino Acids in Water4 Metal Ions and Their Effects on the Reactivity of Acyl Phosphate Monoesters5 The Challenge of Site-Selective Acylation of Carbohydrates in Water6 Conclusions and Prospects

IPA Recycling by Hydrolysis Reaction of TDI Residue

2014 ◽  
Vol 1078 ◽  
pp. 61-64
Author(s):  
Lian Ming Zhang ◽  
Yang Dong Hu ◽  
Lian Ying Wu ◽  
Xi Wang ◽  
Zhong Min Wang
Keyword(s):  
High Purity ◽  
Industrial Production ◽  
Isophthalic Acid ◽  
Toluene Diisocyanate ◽  
Hydrolysis Reaction ◽  
Mass Ratio ◽  
Reaction Conditions ◽  
Multiple Factors ◽  
Hydrolysis Of ◽  
By Products

Thousands of tons of tar residue are gained as by-products in the production of toluene diisocyanate (TDI) using heavy solvent. It is very necessary to recycle the residue. In view of residue composition’s diversity, high purity isophthalic acid (IPA) was obtained as product by hydrolysis of diethyl isophthalate (DEIP) in the residue. Multiple factors which affected the yield of isophthalic acid were investigated. Suitable reaction conditions for industrial production were summarized: the tar residue was grinded to 100 mesh, mass ratio (NaOH: material) was 0.3:1, react in water for 3 hours at 90°C.

Process intensification for enzyme assisted turmeric starch hydrolysis in hydrotropic and supercritical conditions

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yogita P. Labrath ◽  
Prafulla V. Belge ◽  
Uma G. Kulkarni ◽  
Vilas G. Gaikar
Keyword(s):  
Residence Time ◽  
Filtration Rate ◽  
Room Temperature ◽  
Curcuma Longa ◽  
Process Intensification ◽  
Enzyme Treatment ◽  
Starch Hydrolysis ◽  
Reaction Conditions ◽  
Natural Form ◽  
Hydrolysis Of

Abstract The turmeric rhizome (Curcuma longa) contains curcuminoids embedded in the starch matrix. It is thus important to target starch hydrolysis to enhance extraction of curcuminoids. In the case of starch hydrolysis, α-amylase is more efficient when the starch is in a gelatinised form than when it is in its natural form. The present work includes hydrolysis of turmeric starch in its natural and gelatinised forms using α-amylase in hydrotrope solution (HS) and scCO2. The optimum rate of starch hydrolysis was obtained using 200 IU cm−3 of α-amylase, at reaction conditions of 6.5 pH at 328 K when 10% w/w of turmeric powder was stirred at 900 rpm in HSs. The hydrolysis in 15 MPa scCO2 at room temperature required a phase modifier and 40 min of residence time (RT). The enzyme treatment of turmeric powder in HSs increased the filtration rate for curcuminoid extraction (gelatinised and native) compared to untreated turmeric powder.

Metal Ion Catalysis in the Hydrolysis of Potassium Ethyl Oxalate

Nature ◽  
1964 ◽  
Vol 204 (4964) ◽  
pp. 1189-1190
Author(s):  
ROBERT W. HAY ◽  
NEIL J. WALKER
Keyword(s):  
Metal Ion ◽  
Metal Ion Catalysis ◽  
Hydrolysis Of

Metal ion effects on the acid hydrolysis of pyrophosphate

1964 ◽  
Vol 26 (8) ◽  
pp. 1415-1420 ◽  
Author(s):  
J.M. Rainey ◽  
M.M. Jones ◽  
W.L. Lockhart
Keyword(s):  
Acid Hydrolysis ◽  
Metal Ion ◽  
Ion Effects ◽  
Metal Ion Effects ◽  
Hydrolysis Of
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