Acid solvolysis

Recently, 2,6-dioxabicyclo[2.2.1 Jheptane 33 and 2,7-dioxabicyclo[2.2.1 Jheptane 34 were synthesized, and their rates of acidic solvolysis were compared293. Table 1 summarizes the data, along with those for relevant bicydic acetals determined in a similar manner. Tremendous differences in reactivity among these compounds are noteworthy. The approximate relative reactivities under these conditions spun more than five powers of ten. These differences are attributable to ring strain and anomeric... 

Table 1. Relative reactivities of acidic solvolysis of several bicyclic acetals8...

Fu, L., Ferreira, R.A.S., Nobre, S.S., Carlos, L.D., and Rocha, J. (2006) Organically modified silica-based xerogels derived from 3-aminopropyltrimethoxysilane and 3-isocyanatepropyltriethoxysilane through carboxylic acid solvolysis. Mater. Sci. Forum 514-516, 108-112. 

Reactions corresponding to acidic solvolysis of acid halides have also been studied in the gas phase (McMahon, 1978). The results which bear close resemblance to solution processes are illustrated in (82) and (83). 

Fig. 3. A possible mechanistic scenario for acidic solvolysis (Reproduced from Ref. [96] with permission from the authors, copyright American Chemical Society)...

Protonic (deuterio) acid solvolysis of -ide salts is a route to compounds with N-D bonds. Alkali or alkaline-earth nitrides or amides react with DjO or DCl to form products in high isotopic purity, e.g. ... 

In the l960s, Kropp showed that fused bicyclic dienones structurally related to santonin could potentially serve as synthetically useful precursors to either spirocyclic skeletons or hydroazulenones. One of these cases, 91, was successfully used by Marshall and Johnson as the starting point in an elegant synthesis of the spirocyclic sesquiterpene )6-vetivone (Scheme 23). More recently, a variety of bicyclic cyclohexadienones have been studied by Caine and coworkers. For example, bicyclic dienone 92 could be photochemically rearranged to the oxygenated bicyclo[4.3.0]nonenone system 93, along with other rearrangement products, via acetic acid solvolysis of the cyclopropyl ketone intermediate. ... 

The hydrosiiyiation of levulinates followed by acid solvolysis affords 4-methyl-y-butyrolactone with 80-84% e.e. through the silyl ether of 4-hydroxypentanoates, e.g.. 

In 10-2 M HC1, [In(tmpyp)]5+ has bands at 424 nm (e = 390,000), 518 nm (e = 3690), 558 nm (c = 23,200), and 597 nm (e = 4660). The spectrum is similar to that of indium(III)-tetraphenylporphyrin.16 The [In(tmpyp)]5+ is fully water soluble, and rapid acid solvolysis occurs only above 3 M HC1 levels. Refluxing a divalent metal chloride with H2tmpyp in water, and keeping the pH between 3 and 5, is the general method used to prepare the Cu2+, Zn2+, Ni2+, Mn3+, Fe3+, and Co3+ compounds.6 The 642-nm free-base porphyrin band disappears when the incorporation reaction is complete. The high-pH conditions (a) reduce the concentration of unreactive centrally protonated15 porphyrins, (b) minimize the extent of acid catalyzed metalloporphyrin solvolysis reactions,17 and (c) increase the concentration of the often more reactive hydrolyzed metal ion forms.18... 

The marked increase in optical yield in the reaction of pyruvates compared with simple prochiral ketones can probably be ascribed to a ligand effect of the ester moiety in the key intermediate or transition state. Further support of this hypothesis comes from the results for asymmetric hydrosilylation of levulinates153 which, followed by acid solvolysis, affords 4-methyl-y-butyrolactone with more than 80% e.e. through the silyl ether of 4-hydroxybutyrates (e.g. equation 83). 

When -cymene was nitrated in the nucleophilic system ACONO2/AC2O, the product distribution was indeed different (below)i (3c) Subjection of the dienes to strong acid solvolysis gave exclusively 2-nitro- -cymene the total of 82% 2-nitro isomer thus obtained (41% direct + 41% ipso and solvolytic shift) nearly matched the 85% reported for N02 BFi." nitration. These results indicate that the previously unsuspected methyl position actually is the most reactive position toward nitration in -cymene. It was noted also that nitrodeisopropylation could not be avoided in AC2O no evidence was found for existence of a species contain-... 

Questions remained concerning the behavior of the two distinct nitroarenium ions derived from attachment of nitro at C-1, and C-2, respectively. Strong acid solvolysis of the mixture of ipso adducts gave the results shown below. Two major facts were noted, and corresponding conclusions were reached. First, the... 

Acid solvolysis of cycloadduct 83 with trifluoroacetic acid affords a quantitative yield of hexahydroxybenzene, which is an important precursor in the synthesis of rhodizonic acid... 

Hambright et al. (1988) have also studied the kinetics of displacement of the Gd " ion from the gadolinium(III) complex of TSPP by ethylenediaminetetraacetate (EDTA) giving Gd(EDTA) and H2(TSPP) as the main products. This represents the first example of metal removal from a metalloporphyrin by a chelating ligand. A mechanism has been proposed to account for the kinetic data. The water-soluble lanthanide complexes of TMPyP also undergo demetallation in the presence of EDTA (Haye and Hambright 1991). Similar to the acid solvolysis reactions, a linear relationship between log k and the ionic radius of the metal center can be established, and complexes with smaller metal center are more stable toward demetallation by EDTA. 

Figure 16 Outline of the cleavage and characterization of side chains in molecular brushes (a) P/iBA side chains by acid solvolysis, and (b) poly [2-(trimethylsilyloxy)ethyl methacrylate] (PTMS-HEMA) side chains or poly[[2-(methacryloyloxy)ethyl] trimethylammonium iodide] (PMETAI) side chains by basic hydrolysis.

The hydrosilylation of levulinates followed by acid solvolysis afforded 7-valero-lactone. Thus this process may provide a convenient route to the optically active (up to 84% e.e.) 7-valerolactone. 

Cumulene structures also undergo the Myers-Saito reaction. Cyclization of acyclic enyne[3]cumulenes, on the activation of Z-configured dienediyne 38 via acid solvolysis, has been described by Bruckner et al. It has been found that 38 dissolved in /-BuSH/dichloro-methane and treated with a catalytic amount of triflic acid forms the monocyclic cumulene 39. Storage of the mixture for 4 days at room temperature gave the corresponding styrene derivatives 40 and 41 these products form as a result of cycloaromatization via path A (benzoid radical). Independently, after... 

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