Acetic anhydride, solvolysis

A similar lactone was prepared previously by Gilman and coworkers.343 Oxidation of 2-acetoxyfurans with bromine yields an a,jS-unsaturated y-lactone. When the reaction is carried out in carbon tetrachloride a y-bromobutenolide forms, while in a mixture of acetic acid and acetic anhydride solvolysis occurs, with the formation of y-acetoxybutenolide.242... 

A method for the preparation of vanadyl (IV) acetate in non-aqueous media, as reported earlier,1 involves solvolysis of vanadyl(V) chloride in acetic anhydride. However, a quicker... 

Each structural assignment of signals 1-7 in the spectrum of Figure 4 is based on the addition of the authentic compound to the crude ozonolysis mixture, and—aside from peak 1—is also based on additional analytical evidence 2,2,3,3-tetrabromobutane (peak 2), 3,3-dibromobu-tanone (peak 4), and acetic acid were actually isolated while acetyl bromide (peak 3) as well as acetic anhydride (peak 5) were further identified by their sensitivity to solvolysis reactions, particularly hydrolysis and alcoholysis to form the corresponding esters. Diacetylperoxide (peak 6) was identified by the disappearance of peak 6 from the NMR spectrum as well as the disappearance of the typical infrared bands at 1810 and 1835 cm"1 when the reaction mixture was treated with sodium iodide. 

Burgstahler et al. diazotized the sparingly soluble hydrochloride of 3,4-di-r-butylaniline at O-S", treated the filtered solution with sodium fluoroborate, and obtained the diazonium fluond>orate. This salt underwent slow solvolysis in a mixture of acetic acid — acetic anhydride with formation of the corresponding acetate. 

The base 358 is only one of four products obtained when vincadifformine chloroindolenine (295) is allowed to stand with aqueous acetic acid 243). The other products are the corresponding hydroxyindolenine 285 the pen-tacyclic base (362), identical with that obtained earlier by solvolysis of 295 with hot aqueous tetrahydrofuran 244) and a new tetracyclic base, formulated as 3. When heated in acetic anhydride, the chloroindolenine... 

The methoxyberberine betaine (83) will undergo acyl migration in aqueous THF to give the imide methyl isoanhydroberberilate (94). That acyl migration had indeed occurred was shown by the conversion of the betaine (83) into the acetoxy-enamine (95) by acetic anhydride and pyridine, followed by hydrolysis of this by methanolic potassium hydroxide to the known methyl anhydroberberilate (97). The two isomeric compounds (94) and (97) react differently when treated with sodium borohydride in ethanol, the former suffering only solvolysis to noroxy-hydrastinine (98) and the diester (99) and the latter reduction to the ortho-ester (96). This ortho-ester, on A -methylation and further reduction with sodium borohydride, yields hydrohydrastinine and i -meconine. ... 

C-1. The product distribution was found to depend upon the amount of water present in the system, more 6-(bromomethylene)cyclodecanone being obtained with less water present. This observation was explained in terms of capture of the carbonium ion formed from (56 = 2). There would seem to be no examples yet where an intramolecular shift process competes with ring-opening of a cyclopropyl cation. Solvolysis of 10,10-dibromo[4,3,l]propellane in acetic acid-sodium acetate-acetic anhydride gave products formed via the strained bicyclic acetate (56 n = 1, R = Ac). In the absence of acetic anhydride products derived from the corresponding alcohol (56 n = 1, R — H) were obtained as well. Solvolyses of 10,10-dibromo[4,3,l]propell-3-ene in acetic acid-sodium acetate, in the presence and absence of acetic anhydride, and in acetic acid-silver perchlorate, were also reported. Most of the products may have been formed by reaction pathways similar to those observed for (55). ... 

A one-carbon homologation of aldehydes and ketones to carboxylic acids has been reported to involve the Horner-Emmons modification of the Wittig reaction using diethyl-/er/-butoxy(cyano)-methylphosphonate (EtO)2 P0CH(CN)0/-Bu to produce ethyl-/pr/-butoxyacrylonitriles. The /er/-butyl ether group is cleaved by zinc chloride in refluxing acetic anhydride, and the a-acetoxyacrylonitrile is converted to the acid by solvolysis. 

Electrolytes I-III were prepared from TMSPIm precursor by adding (I) trifluoroacetic acid (TFA) or (II, III) acetic acid (AcOH) in a molar ratio of 1 5.5. Equivalents of 4.5 were used for solvolysis, and 1 equivalent served for protonation for formation of ionic liquid. In electrolyte III, a mixture of acetic anhydride as dehydrating agent, and lithium acetate dihydrate as a source of lithium ions were added. Solvolysis and condensation reactions of trimethoxysilanes were stimulated by heat treatment of the mixtures at 120 °C. Lastly, the product was heated under reduced pressure to remove the remaining volatile components from the electrolytes. 

Other examples of the solvolysis of sulfonates to give oxolanes have been reported. Thus, when 2,3-0-benzylidene-tri-0-(methylsulfonyl)-D-arabinitol, in a mixture of 9 M acetic acid and 10 M hydrochloric acid is heated for 30 minutes at 100°, it gives 2,5-anhydro-l,4-di-0-(methylsulfonyl)-D-arabinitol.88 Additional instances of the formation of internal anhydrides (not always well characterized) by acid hydrolysis of various sulfonic esters of alditols have been given by the same authors.88... 

More recently, the uncatalyzed solvolysis of acetic and proprionic anhydrides has been reinvestigated (142). The unusual temperature dependence of the isotope effect was found to be a consequence of widely different values of dEaldT in HgO and in DaO. Since this reaction proceeds via a tetrahedral intermediate, a spurious term adds itself to any real ACp that the reactions involved may possess. The authors state that no mechanistic conclusions can be drawn from the measured dEaldT. [An obvious misprint in the formula for Ac is corrected in a later paper (149).]... 

When copper(i) oxide is treated in benzene with trifluoromethanesulphonic anhydride, the complex (Cu0 S02 CF3)2(C H,), which releases benzene only above 120 °C, is obtained. The trifluoromethanesulphonate ion does not compete with olefins for co-ordination sites on the copper cf. ref. 28, p. 2%) and cationic Cu complexes are formed. Oxidation of alkyl radicals by copper(ii) trifluoromethanesulphonate in acetic acid gives more of the alkyl acetate, by oxidative solvolysis, and less olefin, than oxidation by copper(ii) acetate, the difference in product ratio being due to the greater dissociation of the copper trifluoromethanesulphonate. Silver(ii) complexes Ag (bipy)2-(O3S CF,) (bipy = 2,2 -bipyridyl) may be prepared from the silver(i) complex either by electrolysis or by treatment with silver(ii) oxide and trifluoro-methanesulphonic acid. ... 

It appears that the only anion for which the pathway via the mixed acetic salicylic anhydride is important is that of 3,5-dinitroaspirin [83]. Here the rate enhancement is not large. The rate constant (2.68 x 10 min at 39°C is only 7.3 times greater than that for the hydrolysis of the methyl ester (6.65 x 10 x 55.5 = 3.69 x 10 min ) [83] the corresponding ratio for the hydrolysis of aspirin itself is 175 [77, 79]. Hydrolysis of the anion of 3,5-dinitroaspirin in oxygen-18-enriched water leads to 39 per cent incorporation of the label into the product, 3,5-dinitrosalicylic acid, and solvolysis in 50 per cent v/v aqueous methanol yields 60 per cent of methyl 3,5-dinitrosalicylate [83]. These results can be explained only if the reaction proceeds, at least partially, via the mixed anhydride 52. Three pieces of evidence... 

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