The Patent CH75523 (http://l2.espacenet.com/dips/viewer?PN=CH75523&CY=gb&LG=en&DB=EPD)
named by Jim refers to a main Patent CH74333 (http://l2.espacenet.com/dips/viewer?PN=CH74333&CY=gb&LG=en&DB=EPD)
. A search brought up another, austrian patent AT76500b covering the topic from which the following was translated.by me.
(the patent tag doesn´t accept the austrian patent because it includes a "b" at the end. This speaks of good taste, but is unhandy)
Example: 220 gram of fienely divided sodiumethylsulfate (not anhydrous) and 100 gram also fine divided sodiumnitrite (more than 110% of theory), are mixed and then wettened with 30 ccm water in which was dissolved 7 gram of anhydrous soda (sodiumcarbonate). The mixture is gently heated unil it liquifies (at about 50°C to 60°C was told before in the text). Now the mass is further heated under stirring. A big enough rection vessel has to be used because of the foaming taking place. At about 115°C to 120°C nitroethane starts to distill over with the water. If the receiving vessel isn´t strong cooled big amounts of ethylnitrite escape as gas. When the smixture of salts has dried out it is further processed with heating whereby up to 130°C to 135°C more nitrethane distills over. At higher temperatures the formation of the oil ceases temperatures rising very fast. For driving out the last oil it´s possible to rise temperature as high as up to 200°C. The distillate in the receiving vessel shows a watery and an oily layer, whereby the oily layer consists mainly of nitroethane. The oily layer is lighter as water because of its content of light compounds as are acetaldehyde and ethylnitrite.
In the claims is specified that the addition of water shall be done up to an amount that at ca. 55°C a milky waterlike liquid is formed. The water serves mainly for an equal heattransfer is told and on the necessity of gentle heating and holding the temperature at the lowes level possible for the reaction is disclosed. Yields arn´t great: 35% for nitroethane and in a similar process 50% for nitromethane.
For somebody with access to sodiumnitrate it maybe a way to go. The process might benefit from heating in a microwave for the better heat distribution there I guess.
addons: In the main Patent CH74333 (http://l2.espacenet.com/dips/viewer?PN=CH74333&CY=gb&LG=en&DB=EPD)
dealing with nitromethane the workup is described as follows: The watery and oily layer are separated and the the oil is refluxed for some time to drive out gases (which are possibly olfactoric unsatisfying), dried and distilled using a fractionating column.