Reduction of nitric esters

There are various different methods for reducing nitric esters and thereby removing their nitro group. In most cases the original alcohols are recovered as result of the reaction. 

The oldest and most popular method is reductive hydrolysis by means of alkaline sulphides or hydrosulphides, for instance sodium or ammonium sulphide or the corresponding hydrosulphide, as discussed above in connection with the question of hydrolysis (pp. 9-10). According to Oehman et al. [103] acid hydrolysis of nitroglycerine follows a course similar to that of eqn. (58). Hydrolysis with sulphuric acid (even in the presence of nitric acid) may lead to a transesterification and formation of sulphuric acid esters [104]. 

As for other methods the following reduction processes are known in acetic add by means of iron (Oldham [58]), in acetic acid with iron and zinc (Dewar and Fort [59]), catalytic hydrogenation under pressure over a palladium contact (L. P. Kuhn [60]), or by means of hydrazine in the presence of palladium or platinum. Applying the last method a good yield of alcohol accompanied by NO, N2 and H20 has been obtained by L. P. Kuhn [45]. The reduction can be carried out by means of zinc in the presence of acetic anhydride (Hoffman, Bower, Wolfrom [61]). 

Electrolytic reduction of nitric esters has also been reported (Kaufman, H, J. Cook and S. M. Davis [62]). 

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Physical properties Dipole moments Spectroscopy Hydrolysis of nitric esters Reduction of nitric esters Some 4>thcr reactions of nunc esters Form Jlion of nitric esters Nitric esters as explosives C hemical stability... 

The above mentioned authors also established that the nitrate ion (in contrast with the nitrite ion) slowly undergoes reduction in the presence of sodium hydrosulphide. This leads to the conclusion that the nitrite ion formed during the hydrolysis of nitric esters cannot be produced by the reduction of a nitrate ion. Hence if the nitrite ion is formed direct during the hydrolysis of nitric esters, then it could only be produced by breaking the linkage between the oxygen and nitrogen atoms. 

Compared with nitrous acid ions, nitric acid ions can be slowly reduced in sodium sulfhydrate. The nitrous acid ions are produced from the hydrolysis of nitrate esters, other than from the reduction of nitric acid ions. Thus, the nitrous acid ions are formed, most likely, by the breakage of bonds between oxygen and nitrogen atoms. The effect of sulfhydrate on the hydrolysis of nitrate esters is to reduce the reactants, as expressed in the following reaction mechanism equations. 

Methylsuccinic acid has been prepared by the pyrolysis of tartaric acid from 1,2-dibromopropane or allyl halides by the action of potassium cyanide followed by hydrolysis by reduction of itaconic, citraconic, and mesaconic acids by hydrolysis of ketovalerolactonecarboxylic acid by decarboxylation of 1,1,2-propane tricarboxylic acid by oxidation of /3-methylcyclo-hexanone by fusion of gamboge with alkali by hydrog. nation and condensation of sodium lactate over nickel oxide from acetoacetic ester by successive alkylation with a methyl halide and a monohaloacetic ester by hydrolysis of oi-methyl-o -oxalosuccinic ester or a-methyl-a -acetosuccinic ester by action of hot, concentrated potassium hydroxide upon methyl-succinaldehyde dioxime from the ammonium salt of a-methyl-butyric acid by oxidation with. hydrogen peroxide from /9-methyllevulinic acid by oxidation with dilute nitric acid or hypobromite from /J-methyladipic acid and from the decomposition products of glyceric acid and pyruvic acid. The method described above is a modification of that of Higginbotham and Lapworth. ... 

V.G. Khotin et al, Ibid, 1970(68/25), 243—50 CA 73, 94064n(1970) [A tendency of AN expls to undergo transition from burning to decon when sensitized with RDX or liquid nitric esters was studied. It was found that a 10% content of a sensitizer (RDX or NG) helped the transition of burning Ammonit 6ZhV-20 to expln. An increase to 25% of RDX enhanced this tendency, while a 25% NG content reduced the tendency. The same reduction of tendency was observed when 20% NaCl was added to Ammonit]... 

Nitrotoluenes, Van No strand, NY(1918) 2)M.Kostevitch, "Tarry Matter of Alpha Trinitrotoluene, Part II, Imprd Art Vol-taire,P aris( 1927), 8 3)Sidgwick( 19 37), 259 et seq 4)Davis(1943), 136-7, 147, 149-51 170-1 5>negering( 1950), 139 seq 6) Dept of the Army TM 9-1910( 1955), 146 Alkalies, Action on Nitric Esters. Organic nitrates in general are readily saponified by alkaline solns. A simple metathetical reaction to yield the alkali nitrate and alcohol does not take place instead, as a result of simultaneous oxidation and reduction, alkali nitrite and a variety of products are formed depending on the conditions of the reaction. The resistance of different nitric esters to alkalies varies considerably. Thus, starch nitrate is decomposed much more slowly than cellulose nitrate and amylopectin nitrate still more alowly... 

Clement and Riviere [59] also reported that cellulose acetate or a mixed ester — a nitrate-acetate — can be obtained by reacting cellulose nitrate with acetic anhydride, acetic acid, and sulphuric acid. According to more recent contributions, e.g. Wolfrom, Bower and Maker [60], the reaction should be performed as follows Cellulose nitrate is dissolved in the cold in a little sulphuric add and acetic anhydride, the surplus of acetic anhydride is then hydrolysed also in the cold, and cellulose acetate is extracted with a suitable solvent, such as chloroform. Other methods of acetylating nitrocellulose consist in reduction, for instance with zinc and hydrogen chloride, which entails denitration of the ester, followed by acetylation with acetic anhydride. All these reactions are carried out in the same vessel. Further, it is possible to synthesize mixed esters, cellulose nitrate-acetates, by subjecting cellulose to the action of a mixture that includes nitric acid, acetic add and acetic anhydride in the presence of sulphuric acid (Kruger [61]). The use of a large amount of nitric acid favours the formation of nitrocellulose only. Mixed esters are formed... 

Adipic acid has been prepared by the following methods the action of silver1 or copper 2 on /3-iodopropionic acid the reduction of mucic add with phosphorus and iodine 3 the electrolysis of the potassium or sodium salts of monoethyl succinate 4 the condensation of ethylene chloride or bromide with malonic ester or cyanoacetic ester and subsequent hydrolysis 5 the oxidation of certain fractions of Baku petroleum 6 the oxidation of cyclohexanol or cyclohexanone with nitric acid 7 or potassium permanganate.8... 

To make rosoxacin two heterocyclic systems must be constructed. Workers at the pharmaceutical company Sterling decided to build the pyridine in an ingenious version of the Hantzsch synthesis using acetylenic esters on 3-nitrobenzaldehyde. The ammonia was added as ammonium acetate. Oxidation with nitric acid made the pyridine, hydrolysis of the esters and decarboxylation removed the acid groups, and reduction with Fe(TT) and HC1 converted the nitro group into the amino group required for the quinolone synthesis. 

Glyoxylic acid is a raw material for various chemicals. It is generally produced by enzymatic or nitric acid oxidation of glyoxal, or electrolytic reduction of oxalic acid. It is also known that alkyl esters of glyoxylic acid are obtained by a vapor-phase oxidation of corresponding alkyl esters of glycolic acid [1]. The yield of ester reached 69 mol% at the conversion of 94%. 

As for organic nitrate esters such as nitroglycerine and isosorbide dinitrate, the mechanism of their vasodilating action is now believed to result from their reduction to nitric oxide (NO). Thiols, and particularly glutathione, play an important role in this activation. In the first step, a thionitrate is formed (reaction 10-A) whose N-reduction may occur by more than one route. For example, a GSH-dependent reduction may yield nitrite (reaction 10-B), which undergoes further reduction to NO S-nitrosoglutathione (GS—NO) has also been postulated as an intermediate. 

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