Mild hydrolysis

Strong acids completely hydrolyse cellulose to glucose very mild hydrolysis gives hydrocelluloses with shorter chains and lower viscosity and tensile strength. Under special conditions a large yield of cellobiose is obtained. 

They are formed by heating dibasic acids or their anhydrides with ammonia. The hydrogen atom of the NH group is acidic and can be replaced by a metal. Mild hydrolysis breaks the ring to give the half amide of the acid. See succinimide and phthalimide. 

Methoxypyridazine 1-oxide reacts with methyl /3-aminocrotonate in the presence of benzoyl chloride to give a-(6-methoxy-3-pyridazinyl) /3-aminocrotonate (112) which can be converted by mild hydrolysis into the corresponding acetate (113 Scheme 34) <78JHC1425). 

Dilodosilane (OIS) reagent (or mild hydrolysis o( ketals, acetals or reductive lodination o( ketones and aldehydes. 

The reaction of morpholine enamine of cyclohexanone with 1 mole of phenyl isocyanate has been reported (30,31) to give the monoadduet (49), consisting largely of the trisubstituted isomer, and with 2 moles of phenyl isocyanate, the bis adduct (50). That the bis adduct is a dicarboxyanilide rather than a urea derivative (32) such as 51 was shown by its mild hydrolysis to the ketone (52). Reaction of the morpholine enamine of 2-methylcyclo-... 

The acylation of enamino ketones can take place on oxygen or on carbon. While reaction at nitrogen is a possibility, the N-acylated products are themselves acylating agents, and further reaction normally takes place. The first reported acylation of enamino ketones (72) was that of 129, prepared by acylation of the enamine (113), which was shown to have undergone O acylation because on mild hydrolysis the enol ester (130) could be isolated. A similar reaction took place with other aliphatic acid chlorides (80) and with dibasic acid chlorides [e.g., with succinyl chloride to give 118 above]. 

Only in the case of the pyruvic acid condensation product was it possible to isolate the corresponding ethyl ester under these conditions. This, on mild hydrolysis, reverted to 1-methyl-1,2,3,4-tetrahydro-j8-carbohne-1-carboxylic acid, identical with the starting material, which therefore had the assigned structure 26 (R = CH3) and was not the SchiflF s base 25 (R = CH3). Alkaline hydrolysis of the ester was accompanied by decarboxylation. ... 

The application of enzymes for the mild hydrolysis of esters has been well established as a convenient method, and hence can be regarded as a standard methodology in organic synthesis. Accordingly, the expectation is met that such enzymatic ester cleavage reactions are included in domino processes. In this context, a number of publications describe enzyme-initiated fragmentation reactions. 

Moser et al. (1968) (one of the co-authors was Clifford Matthews) reported a peptide synthesis using the HCN trimer aminomalonitrile, after pre-treatment in the form of a mild hydrolysis. IR spectra showed the typical nitrile bands (2,200 cm ) and imino-keto bands (1,650 cm ). Acid hydrolysis gave only glycine, while alkaline cleavage of the polymer afforded other amino acids, such as arginine, aspartic acid, threonine etc. The formation of the polymer could have occurred according to the scheme shown in Fig. 4.9. 

After mild hydrolysis, neomycin has been shown to give a positive Elson-Morgan reaction , a reaction characteristic of amino-sugarsl52 A method involving this reaction has been made the basis of a quantitative assay for neomycinl l which has been used to determine the neomycin content of fermentation broths. ... 

Dihydroantirhine has also been reached from indole alkaloid strictosi-dine (224). Mild hydrolysis of 224, followed by subsequent sodium borohydride and catalytic reduction, supplied vallesiachotamine derivative 225. Hydrolysis and decarboxylation of 225 gave enamine 226, which could be izomerfzed to 227 by the use of acid. Sodium borohydride reduction of the thermodynamically less stable enamine 226 afforded (+)-18,19-dihydroantirhine selectively, while 227 yielded uniformly 3-epi-18,19-dihydroantirhine (203) (144). 

The conversion of D-mannose (20) into L-gulose (9) was reported by Evans and Parrish,15 and is shown in Scheme 4. D-Mannose (20) was converted into 21 by condensation with acetone, methanol, and 2,2-di-methoxypropane in the presence of an acid, and mild hydrolysis of 21 afforded 22. Methanesulfonylation of 22 provided 23, which was transformed into 24 with sodium acetate in refluxing N,N-dimethyl-formamide. The overall yield of 24 from D-mannose was >50%. Base hydrolysis, followed by acid hydrolysis, afforded L-gulose (9). 

On studying the KDO content of LPS from Xanthomonas sinensis, Volk and coworkers64 found that only one KDO residue per LPS chain is present in this organism. Moreover, the authors observed the formation of 4,7- and 4,8-anhydro derivatives (39 and 40) of KDO (see Scheme 14) under the conditions used for mild hydrolysis of the LPS with acetic acid. Free KDO was also shown to yield the anhydro derivatives under analogous conditions. The structures of these unusual side-products were identified by mass spectrometry, as follows. Reduction of 39 and 40 with sodium borohydride gave the two epimeric mixtu.es, 41 and 42. These were subjected to periodate treatment followed by borohydride reduction, the products separated by paper electrophoresis, and their trimethylsilyl ether derivatives analyzed by... 

Mild hydrolysis with acid for sialic add determination... 

Mild hydrolysis of ethyl 4-oxo-4//-pyrimido[l,2-a]pyridazine-3-carboxylate in 0.1 N sodium hydroxide solution at room temperature afforded monoethyl (3-pyridazinylamino)methylenemalonate (68TL33). 

Hardwoods appear to have a much higher content of such aryl-glycerol-p,y-diaryl ethers because of the more restricted possibilities for condensations in the aromatic ring of sinapyl-type units owing to their two methoxyl groups. This is reflected in the greater susceptibility of hardwood lignins to mild hydrolysis (see Section I). 

Evidence for the participation in lignification of radicals in the form Rfl was not obtained from lignols extracted from simulated lignification experiments with coniferyl alcohol in vitro. Actually more direct proof was obtained here structures, e.g. (XII), that must have arisen from this form of the coniferyl radical were isolated from natural lignins by mild hydrolysis (see Section I). So far only structures derived from combinations of Rd type radicals with Rj, t5rpe radicals have been isolated 47, 705, 776, 777), but evidence for combinations of Rd radicals with Ra radicals has been secured by the detection of 40-(3,4-dimethox3q)henyl)-... 

Several cyclopropylimines have been synthesized and their reactions with a range of nucleophiles have been investigated. Mild hydrolysis of diimine (16) produces, amongst other products, the /3-ketoimine (17), stabilized by intramolecular hydrogen bonding. 

The problem of selective hydrolysis of the acetonlde was studied next. The most practical method consisted of a treatment with acetic acid In aqueous tetrahydrofuran at 65°C which gave a mixture of dlol 103 (major) and trlol 104 (minor) In 77 and 15% yields respectively. Trlol 104 could be converted to 103 by a sequence Involving formation of a 2 3 -orthoester, conversion to the corresponding dl-BOM derivative, then mild hydrolysis. 

---