Acidolysis reaction products

Insights into the acidolysis of ozonides have been gained using ab initio SCF-MO calculations at the split valence 4-31G level (Section 4.16.5.2.1). Comparisons were made between experimental observations of reaction products and calculated stabilities and charge distributions for the species involved <83JOC2366). 

As a by-product of the acidolysis reaction, the 0,/> -dihydroxystilbene (IX) was formed, obviously by the loss of a molecule of formaldehyde from the benzylium ion intermediate (IV) (broken line arrows), a reaction to be regarded as a reverse Prins reaction 29). 

The crude Bjorkman lignin acidolysis mixture contained both polymeric material and a number of more or less low molecular, chromato-graphically visible products in addition to ketol (XII) and was considered to be a potential source not only of further monomeric but also of dimeric and oligomeric degradation products. The polymeric material was readily removed by filtering the crude mixture of reaction products through a short silica gel column (solvent, dioxane-benzene 1 3). 

It seems to the author, however, that other factors besides the ones considered by Bade and Huber must be involved. For example, in the cleavage of tetraalkyltins by mercuric chloride in methanol, bond energy differences are the same as in the acidolysis reaction and so are solvation differences because in both reactions the products are the compounds R3SnCl. Hence if only bond energy differences and R3SnCl solvation differences were important, the same reactivity sequences would be expected. But this is not observed at all as can be seen from the series of relative reactivity (Me4Sn = 100) in Table 13. The reactivity sequence for... 

The employment of 1,3-selective lipases leads to structured TAG where specific acyl groups are confined to either the l-(3-) or 2-acylglycerol position. One of the earliest examples is cocoa butter substitute formed by 1,3-selective lipase-catalyzed acidolysis (reaction 1 of Fig. 3) of palm oil midfraction by palmitic acid (resulting in the replacement of 1-, 3-dipalmityl, 2-oleyl TAG by l-(3-) palmityl, 2-oleyl, 3- (1-) steryl TAG and 1-, 3-disteryl, 2-oleyl TAG, both of which are abundant in cocoa butter). The product... 

Figure 2 shows time conversion curves of 7 in CIXI3 at 100 C. In the absence of TsOH, the disappearance of the diol monotosylate star aft heating for 200 min or longer and occurred in a non-linear manner. The addition of TsC resulted in the marked reduction of heating time for the abrupt consumption of 7, indicating that the acidolysis reaction of 7 t es place autocatalytically. The determination of product distribution showed that 2-phenylcyclohexanone-l and benzoylcyclopentane are obtained in 36 % and 44 % yields, respectively, while TsOH is formed almost quantitatively (Scheme 4). Considering the chemical structures of the ketonic products, it is very likely that 7 imdergoes pinacol-type rearrangement...

Modified triacylglycerols can occur in different polymorphic forms, and these influence the melting properties of the fat, the softening point, the solids content, etc. Analysis of such properties is commonly performed using differential scanning calorimetry (DSC). DSC has been used to determine the physical properties of sTAG formed from interesterification products of triolein and tristearin (Seriburi and Akoh, 1998) and from acidolysis reactions between stearic acid and coconut oil (Rao et al., 2001). 

Stmctured triacylglycerols (see Chapter 6) of the type CGC (where C represents caprylic acid, and G represents GLA) have been prepared in a two-step process. In the first stage the triacylglycerol GGG is prepared from glycerol, GLA, and Candida antarctica lipase. This is then subjected to acidolysis with caprylic acid or interesterification with ethyl caprylate in the presence of Rhizopus delemar lipase. A typical reaction product contains 53% caprylic acid and 47% GLA with CCG (58%) and CGG (29%) as the major triacylglycerols (Kawashima etal., 2001). This particular work was carried out only on a laboratory scale but there are many reports of this type of enzymatic process being carried out on a kilogram scale. At present such compounds are probably too expensive to be incorporated into functional foods and are more likely to be used in pharmaceutical preparations. 

The reaction of formate salts with mineral acids such as sulfuric acid is the oldest iadustrial process for the production of formic acid, and it stiU has importance ia the 1990s. Sodium formate [141-53-7] and calcium formate [544-17-2] are available iadustriaHy from the production of pentaerythritol and other polyhydric alcohols and of disodium dithionite (23). The acidolysis is technically straightforward, but the unavoidable production of sodium sulfate is a clear disadvantage of this route. 

Phosphoric acid [7664-38-2] and its derivatives are effective catalysts for this reaction (60). Reverse alcoholysis and acidolysis can, in principle, also be used to produce polyamides, and the conversion of esters to polyamides through their reaction within diamines, reverse alcoholysis, has been demonstrated (61). In the case of reverse acidolysis, the acid by-product is usually less volatile than the diamine starting material. Thus, this route to the formation of polyamide is not likely to yield a high molecular weight polymer. 

Acidolysis requires the sue of an elevated temperature, the use of an acid catalyst (7), or both. Like alcoholysis, the reaction is reversible and requires the use of an excess of the replacing acid or removal of one of the products from the reaction if a high degree of replacement of the acid radical of an ester by another acid is to be obtained. This can be accompHshed by distilling one of the products from the reaction mixture during the acidolysis. 

A standard UV cell was filled with 3.5mL of a 3 X 10"4 M dichloromethane solution of polyether 2. The solution was then treated with 10 uL of trifluoromethanesulfon-ic acid and the changes in UV absorption of the mixture were monitored. Once the reaction was complete the molar extinction coefficient of the product at 276nm was identical to that of naphthalene, therefore conversions during acidolysis were calculated directly from absorption measurements (At/A ). 

FIGURE 5.16 Production of amides by cleavage of benzhydryl amides. Recognition that removal by acidolysis of benzhydryl protectors from carboxamides gave the amides (B) led to development of benzhydrylamine (BHA) resin (C).33 Treatment with HF of a peptide amide that has been assembled on a BHA resin using Boc/Bzl chemistry gives the peptide amide (D). Peptide amide is also obtainable by ammonolysis of the resin-bound benzyl ester (A), a reaction that is more efficient if gaseous NH3 is employed (see Section 8.3). 

Cr + reacts with H atoms, generated by pulse radiolysis or uv flash photolysis, to give Cr(H20)5H, A = 1.5 X 10 M s . The product may be regarded as the first member of a series of compounds of general formulae Cr(H20)5R which arise from reaction of Cr " with RCl in anaerobic acid solution. It is the most reactive member of the series towards acidolysis (e.g. A (CrH )/fc(Cr(CH3) ) = 2 X 10 ) and in other electrophilic reactions. ... 

Silyl enol ether 139 has also been transformed into D-allose, as shown in Scheme 5. The same methods can be applied to the enantiomeric enol ether derived from camphanate 38, and this allows one to prepare L-allose and its derivatives. Oxidation of 139 with MCPBA in THF (20 °C) led to the product of epoxide acidolysis 147 (69 %) which yielded 148 on heating to 200 °C for 15 min. Addition of 1.1 equiv. of MCPBA converted 148 into lactone 149 which in the presence of MeOH and K2CO3 (20 °C), gave selectively diester 150. Reactions 147... 

The reaction depicted in equation 43 between a nitrile and a lithium amide takes place as a 1,2-addition to the cyano group. The product crystallizes as a dimer (236) in which the lithium atoms are solvated by nitrile molecules and differently bonded to the amidine moieties, as shown by XRD analysis. Low-temperature H NMR spectrum in solution points to uniform chemical environments for both the aryl groups and for the Me—Si groups, and to rapid rearrangement of the Li—N coordination structures. Acidolysis of the dimer in solution yields the corresponding amidine (237) . The crystal structure of the THF-solvated analog of 236 shows dissimilar N—Li bond lengths for the two Li atoms... 

Hydrolysis of lignin in acidic and basic media has received attention due to the rather few and simple degradation products obtained. Acid-catalyzed hydrolysis reactions applied to isolated lignin have been studied by a number of workers. Lundquist (1), for example, subjected Bjorkman lignin to acidolysis and obtained significant yields of monomeric products. A review of the work prior to 1971 has been made by Wallis (2). 

Lipases still offer the potential for an important range of applications since they are able to carry out the reactions of esterification, transesterification (acidolysis or alcoholysis), inter-esterification, or hydrolysis, often with high specificity or selectivity, suitable for the production of high-added-value molecules as shown in Example 1 above (stereospecific alkylation, acylation, or hydrolysis for the resolution of racemic mixtures of acids, alcohols or esters). 

Simple mono- and disubstituted alkenes react to yield 1,3-diols, when the Prins reaction is carried out at elevated temperature. Diols originate from the attack of water on carbocation 18, or through the acidolysis of dioxanes under the reaction conditions. When the reaction is conducted in acetic acid, monoacetates are formed by acetate attack on 18. Dienes resulting from the dehydration of intermediate diols are the products of the transformation of more substituted alkenes. Monoacetates and diols may react further to yield 1,3-diol diacetates. When the Prins reaction... 

Support-bound triazenes, which can be prepared from resin-bound secondary aliphatic amines and aromatic diazonium salts [455], undergo cleavage upon treatment with acids, leading to regeneration of the aromatic diazonium salts. In cross-linked polystyrene, these decompose to yield nitrogen and, preferentially, radical-derived products. If the acidolysis of polystyrene-bound triazenes is conducted in the presence of hydrogen-atom donors (e.g. THF), unsubstituted arenes can be obtained (Entries 8 and 9, Table 3.47). In the presence of alkenes or alkynes and Pd(OAc)2, the initially formed diazonium salts undergo Heck reaction to yield vinylated or alkynylated arenes (Entry 10, Table 3.47). Similarly, unsubstituted arenes can be obtained by oxida-... 

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