Hydrolysis of the Halides

Similarly, the cyanide, acetate and carbonate are unstable in aqueous solution. Hydrolysis of the halides and other salts such as the nitrate and sulfate is incomplete but aqueous solutions are acidic due to the ability of the hydrated cation [AI(H20)6] to act as proton donor giving [A1(H20)5(0H)]-+, (AI(H20)4(0H)2]+, etc. If the pH is gradually increased this deprotonation of the mononuclear species is accompanied by aggregation via OH bridges to give species such as... 

The water-soluble calix[n]arenes 6.3 (n = 4, 6 and 8) containing trimethylammonium groups act as efficient inverse phase-transfer catalysts in the nucleophilic substitution reaction of alkyl and arylalkyl halides with nucleophiles in water (Eq. 6.19).40 In the presence of various surfactants (cationic, zwitterionic and anionic), the reactions of different halides and ketones show that the amount of ketone alkylation is much higher and that the reactions are faster in the presence than in the absence of surfactant aggregates.41 The hydrolysis of the halide is minimized in the presence of cationic or zwitterionic surfactants. 

Aromatic substituent effects due to phosphorus groups have been studied for a number of reactions.47 Thus ester hydrolysis and fluoride-displacement rates, for (56) and (57) respectively, are enhanced by phosphorus substituents (X = O or ), while the rate of hydrolysis of the halide (58) is enhanced for X = , but slowed for X = O.47 A perturbation M.O. analysis of these observations has been presented.48... 

Hydrolysis of the halides yields the corresponding cyclic metaphosphimic acids or their salts, such as Na3(P02NH)3.4 H2O. The carbon and sulphur analogues of these acids are the polymerized forms of cyanic acid and sulphimide ... 

Hydrolysis of the halides and other fnnctionally substituted compounds gives the hydroxides, which are often unstable and spontaneously dehydrate to give the oxides. The first hydrolysis products of the difunctional compounds R2SnX2 are usually the difunctional distannoxanes, XR2SnOSnR2X, which have attracted much attention (see above). 

Ethyl Alcohol and Higher Alcohols. Two general processes exist for hydrating olefins to alcohols. The first is by absorption of olefins in inorganic acids, primarily sulfuric acid, followed by hydrolysis of the intermediate ester. The second process is the direct catalytic hydration of the olefin. The literature on these processes, especially as applied to ethanol and 2-propanol manufacture, is well covered in the general works listed above, and especially by Brooks (22). German work on the catalytic hydration of olefins is described by Kammermeyer and Carpenter (55). The preparation of amyl alcohols via chlorination of pentanes and hydrolysis of the halides is described by Kenyon (56). 

A large number of 9-chloro and 9-bromo bases has been prepared by the action of phosphorus halides on the various alkaloids (11-14, 56, 97, 134, 135, 151, 166, 167). It seems probable that the replacement of hydroxyl by halogen in these reactions takes place with inversion. The hydrolysis of the halides, which is best carried out with silver nitrate in dilute nitric acid, also appears to involve a change in conflguration at... 

The siloxane linkages can result from hydrolysis of the halides. The products of hydrolyses, silanols, are unstable and condense ... 

Hydrolysis of the halides 2, 3 and 4 leads to the hydroxy compounds in a first step. As no triethylamine is used as in the synthesis of 6 and 7 (compare Scheme 2), the released hydrochloric acid acts as a catalyst for the subsequent condensation reaction. This enforces the formation of the polysiloxanes 8,9 and 10 (Scheme 5). 

Hydrolysis of the halides of nonmetals can be classified as a nucleophilic displacement in which a water molecule acts as the nucleophile. The reactions of silicon tetrachloride and boron trichloride are typical. 

Pure oxygenless melts contain no oxide ions in any form, and because of it, pure melts carmot serve as donors of 0 . The melts, which are solvents of the second kind, can affect acid-base interaction in two manners by fixation of oxide ions entering melt and by solvation of conjugated acid or base. These ionic solvents are used in practice for research and applied purposes, however, they contain admixtures of oxide ion donors, which are formed in the melt from initial admixtures of oxoanions such as SO4, CO3, OH . The second way of the appearance of oxide ion admixtures in molten media is characteristic of the melts based on alkali metal halides the process of high-temperature hydrolysis of the halide melts results in formation of hydroxide and, after their dissociation, of oxide ions ... 

Most of the alkylations were carried out by adding a solution of 3,3-ethylenedioxypregna-5,16-dien-20-one in tetrahydrofuran to a solution of lithium in liquid ammonia to the point of color discharge. Treatment with the alkyl halide then furnishes the corresponding 17a-alkyl derivative (10). After hydrolysis of the 3-ketal group, 17a-methyl-, ethyl-, propyl-, butyl-, hexyl-, octyl-, allyl-, and benzylprogesterones are obtained. 

The Cunius degradation of acyl azides prepared either by treatment of acyl halides with sodium azide or trimethylsilyl azide [47] or by treatment of acyl hydrazides with nitrous acid [f J yields pnmarily alkyl isocyanates, which can be isolated when the reaction is earned out in aptotic solvents If alcohols are used as solvents, urethanes are formed Hydrolysis of the isocyanates and the urethanes yields primary amines. 

Hydrolysis of alkyl halides (Section 8.1) A reaction useful only with substrates that do not undergo E2 elimination readily. It is rarely used for the synthesis of alcohols, since alkyl halides are normally prepared from alcohols. 

Several oxohalides are also known, mostly of the types An OaXa, An OaX, An OXa and An "OX, but they have been less thoroughly studied than the halides. They are commonly prepared by oxygenation of the halide with O2 or Sb203, or in case of AnOX by hydrolysis (sometimes accidental) of AnX3. As is to be expected, the higher oxidation states are formed more readily by the lighter actinides thus An02X2, apart from the fluoro compounds, are confined to An = U. Conversely the lower oxidation states are favoured by the heavier actinides (from Am onwards). 

The chiral bicyclic imidazolidine 74 is deprotonated at the 2 position by s-BuLi and the resulting anion adds to alkyl halides, acid chlorides, chlorofor-mates, phenyl isocyanate, and aldehydes. The use of this compound as a chiral formyl anion equivalent seems to be limited, however, since the diastereoselectiv-ity in the addition to aldehydes is poor and hydrolysis of the products 75 to give aldehydes also produces cyclohexane-1,2-diamine, necessitating isolation of the aldehyde as its 2,4-dinitrophenylhydrazone (96SL1109 98T14255). 

In an alternate synthesis of the intermediate ketone, the benzylic halide, 69, is used to alkylate sodium phenoxide. Cyclization of the acid (70) obtained on hydrolysis of the ester by means of trifluoroacetic anhydride again gives 67... 

Another alternative for preparing a primary amine from an alkyl halide is the Gabriel amine synthesis, which uses a phthalimide alkylation. An imide (—CONHCO—) is similar to a /3-keto ester in that the acidic N-H hydrogen is flanked by two carbonyl groups. Thus, imides are deprotonated by such bases as KOH, and the resultant anions are readily alkylated in a reaction similar to the acetoacetic ester synthesis (Section 22.7). Basic hydrolysis of the N-alkylated imide then yields a primary amine product. The imide hydrolysis step is analogous to the hydrolysis of an amide (Section 21.7). 

Exhaustive chlorination of 101 gave a mixture of polychloro derivatives with the 2,3,7,8-tetrachloro species as the major product. To achieve such C-halogenation it is necessary to choose a reaction medium that avoids hydrolysis of the initially formed 5-halides to 5-oxides [76USP3989715 90AHC(48)301]. The 1-halogenated derivatives of 100 and 101 can be readily prepared from the lithiated species (84MI14). 

A number of approaches have been tried for modified halo-de-diazoniations using l-aryl-3,3-dialkyltriazenes, which form diazonium ions in an acid-catalyzed hydrolysis (see Sec. 13.4). Treatment of such triazenes with trimethylsilyl halides in acetonitrile at 60 °C resulted in the rapid evolution of nitrogen and in the formation of aryl halides (Ku and Barrio, 1981) without an electron transfer reagent or another catalyst. Yields with silyl bromide and with silyl iodide were 60-95%. The authors explain the reaction as shown in (Scheme 10-30). The formation of the intermediate is indicated by higher yields if electron-withdrawing substituents (X = CN, COCH3) are present. In the opinion of the present author, it is likely that the dissociation of this intermediate is not a concerted reaction, but that the dissociation of the A-aryl bond to form an aryl cation is followed by the addition of the halide. The reaction is therefore mechanistically not related to the homolytic halo-de-diazoniations. 

Hydrolysis of acyl halides is not usually catalyzed by acids, except for acyl fluorides, where hydrogen bonding can assist in the removal of There are several methods available for the hydrolysis of acyl fluorides. ... 

Other indirect methods are treatment of the halide with silyl-thiols and KH, followed by treatment with fluoride ion and water, and hydrolysis of Bunte salts (see 10-41) is another method. 

An alternative to the Gabriel synthesis, in which alkyl halides can be converted to primary amines in good yields, involves treatment of the halide with the strong base guanidine followed by alkaline hydrolysis. There are several alternative... 

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