Acidolysis procedure

Preferred Acidolysis Procedure 6.1.4.1 Preparation of the Acidolysis Reagent... 

The rate of derivatization of different compounds varies when trimethylsilyl derivatives are prepared (Lundquist and Kirk 1971). Another complication arises from the fact that enolization and subsequent formation of enol derivatives occur during the derivatization treatment (Lundquist and Kirk 1971). Ketol la (Fig. 6.1.1), for example, has been shown to give rise to three different derivatives (Fig. 6.1.3) (Lapierre et al. 1983a). One approach for overcoming these difficulties consists of derivatization under mild conditions in combination with a gas chromatographic study of the rate of derivatization (Lundquist and Kirk 1971, Pometto and Crawford 1985). A second solution to this problem consists of performing the silylation under conditions that secure complete derivatization and analysis of all types of derivatives formed (Lapierre et al. 1983a). The latter principle has been adopted in the preferred acidolysis procedure. 

The ester (72) (with the OH group appropriately protected) has been transformed into the phosphacyclohexane (75) by way of (73) and (74) by processes of reduction, acidolysis, and peroxide oxidation. Variations of this procedure are also... 

An adapted Strecker reaction using NaCN and NH2OH was the first procedure used for obtaining racemic TV-hydroxyamino acids 14 Although it has been modified repeatedly, 15-19 the yields are rather low. Racemic TV-hydroxyamino acids were also prepared as early as 1894 by addition of nitrogen oxide to the sodium salt of diethyl C-alkylmalonate, followed by acidolysis with concentrated hydrochloric acid.120,21 The procedure has been reinvestigated later with a 45-65% overall yield 19 ... 

In the late 1980s various asymmetric procedures for the synthesis a-hydrazino acids, based on the electrophilic amination of an enolate bearing a chiral auxiliary by a dialkylazodi-carboxylate, have appeared in the literature (Table 1)J55 68 72i The a-hydrazino acid is recovered in high yield after cleavage of the chiral auxiliary and acidolysis of the Boc groups in 63. The D-enantiomer is obtained with 65, A and the L-enantiomer with 66,[551 67,169 71 and 68.[70] A chiral auxiliary is not required for hydrazinating chiral (i-hydroxyesters.172 ... 

Different chemical procedures may be used for the synthesis of alkyd re si ns. The choice is usually dictated by the selection of the starting ingredients. Procedures include the alcoholysis process, the fatty acid process, the fatty acid-oil process, and the acidolysis process. 

Removal of the 9-phenylfluoren-9-yl group has been accomplished by three different procedures acidolysis with trifluoroacetic acid,2 9 10-12 catalytic hydrogenolysis,3 7 9 14 15 and dissolving metal reduction.15... 

Recently, Freudenberg and co-workers (//) briefly reported the isolation of small amounts of dehydrodiconiferyl alcohol (XXVII) from the methanolysis of wood at room temperature. By this procedure, again, only benzyl aryl ether-linked terminal dimers can be obtained whereas acidolysis liberates (a- and) /3-ether-linked phenylcoumaran systems from the core of the lignin molecule as well. 

The present procedure is that described by the submitters.3 a-Phthalimido-o-toluic acid has also been prepared by the acidolysis of the corresponding ethyl ester, obtained from the reaction of ethyl a-bromo-o-toluate with potassium phthalimide.8... 

Lignins can be detected and characterized by analysis of their low-molecular weight acidolysis products, and it is this application of acidolysis that is the subject of the current presentation Routine analytical procedures have been developed only for monomeric acidolysis products Therefore, analysis of such compounds is the primary concern in this section Analysis of dimeric acidolysis products is, however, of great value for the characterization of lignins and is treated under a separate heading (Sect 6 16)... 

A variety of work-up procedures have been described in the literature. Lundquist and Kirk (1971) applied gel permeation chromatography to separate the acidolysis monomers from polymeric materials in the initial step. This is, however, not a requirement when the acidolysis monomers are analyzed by gas chromatography as their trimethylsilyl derivatives. 

Pometto AL III, Crawford DL (1985) Simplified procedure for recovery of lignin acidolysis products for determining the lignin-degrading abilities of microorganisms Appl Environ Microbiol 49 879-881... 

In Table 6 4 3 are shown the yields of monomeric products recovered from milled wood lignin (MWL) and enzymatically liberated lignin (EL) fractions successively isolated from poplar wood and subjected to various degradation procedures (Lapierre 1986) These values reveal that acidolysis, which should allow the characterization of the same lignin structures as thioacidolysis,... 

TFA at higher temperatures,or TFA/thioanisole where the push-pull mechanism remarkably increases the rate of acidolysis,f l liquid HF/pyridine,t °l BBrj/CHaQa, or BBrj/TFA for longer peptide fragments.By these procedures also the benzyl-type side-chain protection is cleaved as well as Arg(Tos). Additionally, numerous sulfonic acids were shown to efficiently remove the Z group, such as methanesulfonic acid, trifluoromethanesulfonic acid, or fluorosulfonic acid mainly in CH2CI2 or Since the acidolytic removal of the... 

Fluorenyl esters have been recommended as a useful alternative to the benzhydryl (diphenylmethyl) esters in the protection of amino acids.P l They are readily prepared from 9-diazofluorene and the amino acid following a similar procedure to that for the benzhydryl esters. Cleavage is accomplished by mild acidolysis or hydrogenolysis. 

All polymerizations were carried out by melt acidolysis based on a procedure described in a U.S. Patent (6). A general procedure was used for all the experiments (4). 

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