Methylester hydrolysis

It can be obtained from castor oil. Methanolysis of castor oil yields methylester of ricinoleic acid. Pyrolysis at 500°C forms n-heotaldehyde and methyl-undecylenate. Hydrolysis of latter... 

Quinoxaline-2- tissues Swine liq-liq partns, silica gel column cleanup, methylester derivative Aik hydrolysis, HCI 24 with 3% silar IOC Gas-Chrom Q Helium EI-MS 70-95% 30 ppb/ 419... 

The work of Bender et al.25U252 on the hydrolysis of the mono-amide and mono-methylester of phthalic acid indicated that the amide hydrolysis proceeded via the anhydride. However, it has been reported that the undissociated carboxyl group is the reactive species in the hydrolysis of such esters as methylhydrogen 2,3-di-(r-butyl)succinate and methylhydrogen-S -dimethylphthalate253. 

Thus, the N-protected indoline 211 (Scheme 33), on regiospecific metallation followed by bromination with dibromotetrafluoroethane provided the 7-bromoindoline 212. Removal of the urethane functionality and subsequent benzylation of the free amine formed, furnished the tertiary amine 213. Addition of oxazoline 214 derived from 2,4,5-trimethoxybenzaldehyde to the Grignard reagent prepared from 213, followed by acid hydrolysis of the resulting biaryl 215 afforded the 2-substituted isobutylbenzoate 216. Catalytic N-debenzylation of the methylester 217 obtained by transesterification of 216 yielded oxoassoanine (203). 

Bornscheuer et al. (1992) Batch Esterification, hydrolysis, and transesterification of 3-hydroxyhexanoic acid methylester Lipase from Pseudomonas cepacia... 

There are many pharmaceutical applications for the modification of one enantiomer over another, and to this end, many have studied these selective reactions in carbon dioxide. Glowacz et al. (1996) studied the enzymatic hydrolysis of triolein and its partial glycerides and found that stereoselectivity depends on reaction time and enzyme water content. They suggest that the water content varies the local environment of the enzyme in carbon dioxide and changes the local pH value. Rantakyla et al. (1996) also found that the hydrolysis of one stereoisomer over another was water-dependent. They studied the hydrolysis of 3-(4-methoxyphenyl)glycidic acid methylester and found that the 2S,3R enantiomer hydrolyzed more than fivefold faster than the 2R3S form. 

The resulting acetate 116 is formulated as the tawis-isomer, too. The carboxylic group was then converted by selective reduction with diborane to the alcohol 117. The alcohol function was converted to the nitrile 119 via the tosylate 118 and displacement of the tosylate group with sodium cyanide. Methanolysis led to the methylester 120 because the acetate moiety was not cleaved under these conditions (MeOH/HCl). Hydrolysis with base yielded the deprotected lactone acid alcohol 121, which was purified by converting it into the methylester 122. 

Butandioic Acid (5)-2-Amino- -4-methylester E21a, 825 (1 -Acylamin-2-oxo-idazolidin-Der.-Hydrolysis)... 

Settimj et al.6 described a gas chromatographic method for the estimation of reserpine and rescinnamine involving alkaline hydrolysis of the alkaloids and subsequent esterification of the acids formed by means of diazomethane. Reserpine gave quantitatively 3,4,5-trimethoxyben-zoic acid methylester, whereas the trars-3,4,5-trimethoxycinnamic acid methylester, which should be expected for rescinnamine, was partly isomerized to the cis-trimethoxycinnamic acid methylester or formed an adduct with a molecule of methanol, yielding 3-methoxy-3-(3,4,5-tr1-methoxyphenyl) propionic acid methylester. 

Membranes are being frequently employed in the manufacturing of pharmaceuticals in combination with a bioreactor for enzymatic reactions. In DSM such a combination has been studied for the production of S -ibuprofen, via the hydrolysis of the (R,S)-ibuprofen methylester coupled to a racemization of the unwanted enantiomer. The esterase used for the above conversion is strongly deactivated by the product. To solve this problem, an ultrafiltration membrane unit has been coupled to the reactor, to remove in situ the product formed. The application of the ultrafiltration has led to a twofold increase of the conversion/productivity, as shown in Fig. 11. 

First we wanted to avoid the formation of a middle chain monocarboxylic acid (pelargonic acid) as a by-product. Second oleic acid or its methylester are, not industrially available in pure form. Produced by hydrolysis or transesterification of tallow or vegetable oil, they are always contaminated by other C18-fatty acids/methylesters, as for example linoleic acid/methylester, which cannot be separated in an economic manner. 

The most reactive of halides of acids are iodides, in the case of esters the most reactive are gener y methylesters of carboxylic acids. The most important transformations of carboxylic acids and their derivatives include esterification and hydrolysis of esters and amides. Esters and amides are hydrolysed in both acid and alkaline media. 

BOC-(D-Phe)2-OMe was synthesized with 78% yield by using isobutyl chloroformate and triethylamine, from BOC-D-Phe which had been prepared from D-phenylalanine, BOC-ON and D-phenylalanine methylester. BOC-(D-Phe)4-OMe was synthesized with water soluble carbodiimide (WSCI) with 84% yield from BOC-(D-Phe)2 prepared by alkaline hydrolysis of BOC-(D-Phe)2-OMe and (D-Phe)2-OMe prepared from BOC-(D-Phe)2-OMe by removing the BOC group in 4N-HCl/ethyl acetate. (D-Phe)4 HCl was synthesized similarly with 80% yield from BOC-(D-Phe)4-OMe, first by alkaline hydrolysis and then by removal of the BOC group. Similarly, the following peptide derivatives were synthesized to characterize the enzyme Boc-D-Phe, D-Phe tert-butyl ester, (D-Phe)2 HCl, Boc-(D-Phe)2, (D-Phe)2 methyl ester-HCl, Boc-(D-Phe)2 methyl ester, (D-Phe)3-HCl, Boc-(D-Phe)3, Boc-(D-Phe>3 methyl ester, Boc-(D-Phe>3 tert-butyl ester, (D-Phe)4-HCl, Boc-(D-Phe)4, Boc-(D-Phe>4 methyl ester, L-... 

The sodium salts of Q -sulfo fatty acid methylesters are soluble in water and resistant to hydrolysis in the pH range of 3-10. They are also only slightly sensitive to water hardness and offer good detergency in combination with other surfactants. Their foaming ability decreases strongly from the lauric methylester to the stearic methyl ester. 

The second aromatization process therefore proceeds as shown in Figure 2. These findings are at variance with previous assumptions and with experimental evidence which seemed to indicate that the aromatic carboxyl group is activated.In previous experiments we attempted to determine the site of activation of -succinylbenzoic acid (II) in a different way the enzymically formed OSB-coenzyme A ester was isolated and methylated with diazomethane (Fig. 3). Mild alkaline hydrolysis yielded the "aliphatic" methylester of -succinylbenzoic acid (X). 

The ester linkage in depsides can be hydrolyzed with concentrated H2SO4 at 0°C or with aqueous or methanolic KOH. The corresponding phenolic carboxylic acids, their methylesters, or their decarboxylation products are obtained. Hydrolysis is especially easy with depsides having a/5-positioned carbonyl group in the 6 and 6 side chains. One therefore obtains from... 

As mentioned in the case of enals, whole-cell systems often show undesired side activities in this case ester hydrolysis took place quantitatively in the reaction medium (due to the presence of hydrolases, such as proteases and lipases) and the optically pure chloro acids were obtained. The bioreduction of the same compounds has recently been revised, employing isolated ene reductases OYEl-3, to prevent hydrolysis and demonstrate conclusively that the reduction in yeast cells is due to the action of ene reductases and the methylesters are accepted substrates [118]. (H)-enantiomers are obtained from ( )-stereoisomers of the starting materials, and the opposite (S)-enantiomers are obtained from the (Z)-isomers (isomerism-based strategy. Figure 3.2a), though with lower ee values. The saturated products obtained (either esters or acids) can be employed as synthones in a large variety of applications (e.g., (S)-98 is the key precursor of the natural antibiotic armentomycin). 

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