Secondary aliphatic nitramines

Preparation of Secondary Aliphatic Nitramines. A solution of / ,/ -bis(cyanoethyl)amine (10.0 grams, 0.08 mole) in 60 ml. of methylene chloride was cooled to —30°C., and 5.3 grams (0.04 mole) of nitronium tetrafluoroborate was added over a 10-minute period. The mixture was stirred for 1 hour at 0°C., then 4 hours at room temperature. The hydro-fluoroboric acid salt of / ,/ -bis (cyanoethyl) amine, 8.3 grams, 99% yield,... 

The filtrate was concentrated under reduced pressure to leave crude / ,/ -bis (cyanoethyl) nitramine, which after one recrystallization from methanol gave a product (3.3 grams, 62% yield) which melted at 55.5°-57.0°C. (literature value (2) 55.5°-56.8°C.). The other secondary aliphatic nitramines prepared, along with their yields and melting or boiling points are given in Table II. 

Fragnentation of some Secondary Aliphatic Nitramines. Migration of the Nitro Group in Heterocyclic Nitramines Organic Mass Spectrometry 3, 13-21. 

The reaction of dinitrogen pentoxide with primary aliphatic nitramines and amines leads to deamination and the formation of a nitrate ester as the major product. Consequently, dinitrogen pentoxide cannot be used for the synthesis of primary nitramines. In contrast, both primary and secondary arylamines undergo efficient A-nitration with dinitrogen pentoxide in chlorinated solvents. ... 

G.S.Myers G. F. Wright, pp 257-270 (The Nitration of Aliphatic Diaikylchioramines) 6)K.K.Carroll G.F.Wright, pp 271-283 (The Nitration of Drn cctylaminc) 7)C-N-Srnart G. F.Wright, pp 284-293 (A New Method of Preparation of Primary Nitramines) 8)T.Connor et al, pp 294-308 (The Medium Used in Nitration of Secondary Aliphatic Amines)... 

At present there are four good methods for preparing secondary nitramines. They are the oxidation of nitrosamines by peroxytrifluoro-acetic acid (5), the chloride-ion catalyzed direct nitration of amines (3), the nitrolysis of dialkylamides with nitric acid (16), and the alkaline nitration of amines with acetone cyanohydrin nitrate (6). We have found that treating two equivalents of several secondary aliphatic amines... 

Properties and reactions of nitramines Secondary nitramines are neutral, primary nitramines form salts with bases, but an excess of alkali often causes decomposition to the carbonyl compound, nitrogen, and water. Secondary nitramines and aqueous alkali afford nitrous acid, aldehyde, and primary amine. Acids decompose primary aliphatic nitramines with formation of nitrous oxide in a reaction that has not yet been clarified thus these compounds cannot be hydrolysed by acid to amines in the same way as nitrosamines, although, like the latter, they can be reduced to hydrazines. Primary and secondary aromatic nitramines readily rearrange to C-nitroarylamines in acid solution. Most nitramines decompose explosively when heated, but the lower aliphatic secondary nitramines can be distilled in a vacuum. 

Satisfactory yields of nitramines were obtained by reacting two equivalents of secondary aliphatic amines with NO BF4 in methylene chloride solution (Table XXV). 

A number of secondary high explosives containing both nitramine and nitrate ester functionality have been reported. Aliphatic examples include A-nitrodiethanolamine dinitrate (DINA) (110), prepared from the nitration of diethanolamine with nitric acid-acetic anhydride in the presence of zinc chloride,and A,A -dinitro-A,A -bis(2-hydroxyethyl)oxamide dinitrate (NENO) (111), prepared from the mixed acid nitration of A,lV -bis(2-hydroxyethyl) oxamide . 

More recently, Polish chemists have reported a synthesis of both aryl and aliphatic secondary nitramines by treating amine substrates with ethyl magnesium bromide followed by reaction with n-butyl nitrate (Equation 5.8). This method, which uses nonpolar solvents like hexane or benzene, has been used to synthesize aliphatic secondary nitramines, and At-nitro-A-methylanilines which otherwise undergo facile Bamberger rearrangement in the presence of acid. The direct nitration of At-unsubstituted arylamines usually requires the presence of an electron-withdrawing group. Reactions are retarded and yields are low for sterically hindered amines. 

Ordinarily, alkyl nitrate esters will not nitrate amines under neutral conditions. However, Schmitt, Bedford and Bottaro have reported the use of some novel electron-deficient nitrate esters for the direct At-nitration of secondary amines. The most useful of these is 2-(trifluoromethyl)-2-propyl nitrate, which nitrates a range of aliphatic secondary amines to the corresponding nitramines in good to excellent yields. Nitrosamine formation is insignificant in these reactions. 2-(Trifluoromethyl)-2-propyl nitrate cannot be used for the nitration of primary amines, or secondary amines containing ethylenediamine functionality like that in piperazine. Its use is limited with highly hindered amines or amines of diminished nucleophilicity due to inductive or steric effects. 

Emmons and co-workers prepared a series of aliphatic secondary nitramines by treating amines with a solution of dinitrogen pentoxide in carbon tetrachloride at —30 C (Equation 5.9). The amine component needs to be in excess of two equivalents relative to the dinitrogen pentoxide if high yields of nitramine are to be attained. This is wasteful because at least half the amine remains unreacted. However, yields are high and there is no reason why the amine cannot be recovered as the nitrate salt. The method is particularly useful for the nitration of hindered secondary amines substrates such as those with branching on the a carbon. 

Methylenediamines are readily synthesized from the reaction of secondary amines with formaldehyde. Many aliphatic amines are too basic for direct nitration without a chloride catalyst, and even then, nitrosamine formation can be a problem. Their conversion into intermediate methylenediamines before nitration is therefore a useful route to secondary nitramines. The success of these nitrolysis reactions is attributed to the inherent low basicity of the methylene-diamine nitrogens. 

A solution of dinitrogen pentoxide in methylene chloride-acetonitrile also yields secondary nitramines from symmetrical methylenediamines. When the substiment is aliphatic or heterocyclic the nitrolysis occurs specifically at the aminal methylene and yields of secondary nitramine between 25 % and 54 % are reported. 

W.J.Chute et al, pp 89-103 (Dinitroxydiethyl-nitramine) 2)G.E.Dunn et al, pp 104-113 (Relative Basicity or Secondary Amines in Acetic Acid) 3)W.J.Chute et al, pp 114-137 jTjig Esse of Nitration Among Aliphatic Secondary Amines) 4)J.C.MacKenzie et al, pp 138-153 (The Role of Electropositive Chlorine in the Nitration of Lysidine) 5)... 

Primary plosophores include the following groups nitrate ester, aromatic nitro, aliphatic nitro, and nitramines while the secondary plosophores include the remainder, such as azo, azido, nitro so, peroxide, fulminate, chlorate, bromare, perchlorate, per-bromate, etc groups... 

Group V Solid, noncyclic, aliphatic secondary nitramines containing terminated ethylenenitrate and (or) 2,2-dinitropropyl groups ... 

The reagent converts aliphatic secondary amines into nitramines in excellent yield a solution in carbon tetrachloride is added to a carbon tetrachloride solution of excess amine at —25°. 

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