Written in English
|Statement||by William H. Berg.|
|LC Classifications||Microfilm 42568 (Q)|
|The Physical Object|
|Pagination||xvi, 226 leaves|
|Number of Pages||226|
|LC Control Number||91954300|
The present review outlines recent examples of enzyme-based resolution procedures for amino acids via the hydrolysis of their esters. The resolutions have been achieved by using proteases (α-chymotrypsin, subtilisin and other microbial proteases, and sulfhydryl proteases of plant origin) and lipases. Relevant work utilizing yeast and other microbial cells is also by: A New Method for the Esterification of Sulfonic Acids A. A. Padmapriya, G. Just and N.G. Lewis Synthetic Communications 15(12), () HTML by Rhodium. Abstract. Sulfonic acids can be smoothly converted to their methyl and ethyl esters by reaction with trimethyl and triethyl orthoformate, respectively. Hydrolysis of linear aliphatic monoesters was carried out in aqueous solutions with hydrochloric acid or polystyrene sulfonic acids (PS-S) of various degrees of sulfonation as catalysts and the rates of hydrolysis were compared. Hydrolysis of esters is an exergonic reaction. However in the absence of a catalyst the activation energy barrier is often high enough to prevent hydrolysis from occurring at a significant rate. There are in fact a lot of stable ester compounds in biological organisms that do not hydrolyze at an appreciable rate unless a specific esterase enzyme is.
Sultones are the cyclic esters of sulfonic acids. 1,3-Propanesultone (PrS) is one of the simplest sultones, and is a useful sulfoalkylating agent in organic synthesis, medicinal chemistry, and surfactant production. It has good solubility in water ( g mL −1), with which it slowly reacts yielding 1-hydroxypropanesulfonic acid (pK a ). Students work collaboratively to prepare and characterize the library of esters and complete and evaluate the feasibility of the enzymatic hydrolysis for the goals of the case. Students make extensive use of 1 H NMR to characterize products and to determine the product or products of the enzymatic reaction. It has been established that for simple carboxylic esters the basic ester skeletal framework CC(O)OC is planar or near planar and that the (Z)-form is much more stable than the(E)-form.1) It has been also proposed that diesters of oxalic acid mainly exist as the s-trans conformers.2) Accordingly, a noteworthy feature of cyclic oxalate esters 2 formed from. The enzymatic hydrolysis of a series of carboxylic esters by carboxylesterase NP has been investigated in order to determine the scope and limitations of this enzyme. 2‐Substituted propionates were hydrolyzed with high enantioselectivity when an aromatic moiety was part of the 2‐substituent.
Hydrolytic activity of the hexapeptide series, the cyclic form in particular, was larger than that of the nonapeptide series in many cases such as in the hydrolysis of N‐protected amino acid p‐nitrophenyl esters (Z‐Gly‐ONp, Boc‐Ala‐ONp, Z‐ (l and d) ‐Leu‐ONp, Boc‐ (l and) ‐Phe‐ONp) and anionic 3‐nitro‐4. Chapter 15 – Carboxylic Acids and Esters Occurrence, Names, and Physical Properties of Carboxylic Acids Almost all naturally occurring acids are carboxylic acids (-CO 2H). They are weak acids (Chapter 8, p. ). The other type of acid your book mentions, sulfonic acids (RSO 3H), are generally strong acids and don’t occur naturally. Abstract Ethylene carbonate, a cyclic organic carbonate widely used industrially, is toxic when metabolically converted to ethylene glycol. A rat liver enzyme active in catalyzing the ring opening has been purified to electrophoretic homogeneity and found to be active in the hydrolysis of ethylene, vinylene, and propylene carbonates to CO2 and the respective glycols. Reactions at surfaces. The six-membered ring was reported to be selectively reduced in CHEC-II(). More recent examples using Pd/C or Raney-Ni confirm this urization of methylthio substituents attached to the six-membered ring has been reported, but, depending on the nature of the other substituents on this ring, it can lead to also to.