Process for the manufacture of nitric acid esters

Process for the preparation of nitric acid esters of organic hydroxyl compounds selected from the group consisting of alkylene glycol monoalkyl ethers, polyalkylene glycol monoalkyl ethers and polyalkylene glycols in which at least 92% of the organic hydroxyl compound is converted to a nitric acid ester selected from the group consisting of alkylene glycol monoalkyl ether mononitrates, polyalkylene glycol monoalkyl ether mononitrates and polyalkylene glycol nitrates, which process comprises the steps of:

• (1) reacting the organic hydroxyl compound with nitric acid in an amount of from 180% to 220% of the stoichiometric requirement for complete nitration in the presence of sulphuric acid in such an amount that the mole ratio of water to sulphuric acid (FWSR) at the end of the reaction is from 0.2:1 to 2.5:1 and in the presence of an organic solvent which is inert to the reaction conditions in an amount of 200 to 2000 ml per mole of hydroxyl group, followed by
• (2) separating off first of all a spent acid comprising substantially sulphuric acid and water from the reaction mixture, leaving substantially all the unreacted nitric acid in solution in the organic solvent,
• (3) washing the remaining reaction mixture after removal of the sulphuric acid to remove nitric therefrom as a separate solution from the already separated sulphuric acid and to leave the solvent containing the desired nitric acid esters,
• (4) substantially neutralizing the residual acidity of the organic solvent solution, and
• (5) removing the solvent to leave the nitric acid ester.