GB587992A - Improvements in and relating to the production of organic nitrogen compounds - Google Patents

Abstract

Organic nitro compounds, for example, dinitro compounds, nitro alcohols and nitro-nitrate compounds, are produced by reacting a mixture containing at least one compound selected from an aliphatic mono-olefine having at least 7 carbon atoms, or a cyclic mono-olefine having at least 5 carbon atoms or substituted derivatives of such aliphatic or cyclic mono-olefines with nitrogen tetroxide in the presence or absence of oxygen or air, and treating the reaction product with water or a lower aliphatic alcohol containing less than six carbon atoms which hydrolyses the nitrites formed in the nitration to the nitro alcohols. If desired, the nitration may be carried out in the presence of a solvent inert to the reactants. Examples of suitable mono-olefinic compounds which may be so reacted are trimethylpentenes, cyclohexene, oleic acid, cracked paraffin wax and ethyl acrylate. With some olefinic hydrocarbons and their derivatives, particularly the C7-C10 aliphatic olefines and the cyclic olefines, it is preferable to carry out the nitration in the presence of an oxygen - containing solvent selected from: saturated aliphatic, alicyclic, or aliphatic-alicyclic compounds containing carbon, hydrogen and oxygen only and having no oxygen-containing groups except ether or ester groups and no 3- or 4- membered rings, but excluding esters of formic acid; saturated heterocyclic or aliphatic - heterocyclic compounds containing carbon, hydrogen and oxygen only and having only carbon and oxygen in the ring and no other groups except hydrogen, hydrocarbon, ether or ester groups but excluding such compounds containing 3- or 4-membered rings; preferably the solvent boils below 180 DEG C. and melts below 50 DEG C. Mixtures of these solvents alone or with other inert solvents may be used but should be such as can be boiled off below 180 DEG C. Examples of some of these solvents are alkyl mono-ethers, diethers, dioxan, tetrahydrofuran, and esters of saturated aliphatic mono-carboxylic acids. With other olefinic compounds, other solvents for nitrogen tetroxide may be employed. It is preferred to operate the process in the liquid phase and at atmospheric pressures and temperatures. The oxygen may be introduced continuously or at various stages in the reaction. In working up the reaction product, water is preferred when the nitro alcohols formed are water soluble since they may then be isolated from the aqueous solution by solvent extraction; the dinitro and other nitro-compounds can then be recovered from the residual oil. Before the water or alcohol treatment, the solvent and remaining nitrogen oxides should preferably be removed from the reaction product. The dinitro compounds may also be recovered by freezing out from the reaction product before the water treatment and before or after removing solvent. Again, if a solvent boiling below 100 DEG C. is used in the main reaction, the product may be well mixed with water, the solvent distilled off under reduced pressure, the aqueous layer separated and the nitro alcohols isolated therefrom by solvent extraction, and the dinitro-compounds and nitro-nitrates recovered from the residual oil. Also, a water immiscible solvent may be used in the main reaction, the product treated with water and the aqueous layer containing nitro-alcohols separated from the solvent layer of dinitro-compounds and nitro-nitrates from which the nitro-compounds may be recovered. If the nitro-alcohols are insoluble in water, then after water-treatment the washed product may be fractionally distilled to isolate the nitro-alcohols, dinitro-compounds and nitro-nitrates. In a further modification, the nitration products are treated with methanol and the dinitro compounds isolated by freezing out from the methanol solution. In examples: (1) 2,4,4,-trimethylpentene-1 was reacted with a solution of nitrogen tetroxide in dry methylated ether at 0 DEG C., the product being freed of solvent, washed with water, dried and fractionated, yielding 2,4,4-trimethyl-1,2-dinitropentane and 2,4,4-trimethyl-1-nitro-pentanol-2. (2) Oleic acid was reacted with an ether solution of nitrogen tetroxide and the product washed with water after removal of solvent, giving a product containing dinitro-stearic acid and mono-nitro mono-hydroxy stearic acid and its nitrate ester. (3) Nitrogen tetroxide was reacted with an ethereal solution of cracked paraffin wax consisting of C15 hydrocarbons, containing 45 per cent mono-olefines, the product being stripped of solvent, water washed and the saturated hydrocarbon portion distilled off; the residue comprised a mixture of nitro-alcohol and dinitro compound. (4) Nitrogen tetroxide and cyclohexene were reacted in ether in the presence of a stream of oxygen; after removing solvent the product was waterwashed and 1-nitro-cyclohexanol-2 isolated by solvent extraction from the washings and 1,2-dinitro-cyclohexane recovered from the insoluble residue by distillation. According to the Provisional Specification, any cyclic monoolefine may be used as a starting material. Specifications 572,949 and 580,260 are referred to.