Nitrites, listing potassium nitrite

The reaction of alkyl halides with metal nitrites is one of the most important methods for the preparation of nitroalkanes. As a metal nitrite, silver nitrite (Victor-Meyer reaction), potassium nitrite, or sodium nitrite (Kornblum reaction) have been frequently used. The products are usually a mixture of nitroalkanes and alkyl nitrites, which are readily separated by distillation (Eq. 2.47). The synthesis of nitro compounds by this process is well documented in the reviews, and some typical cases are listed in Table 2.3.92a Primary and secondary alkyl iodides and bromides as well as sulfonate esters give the corresponding nitro compounds in 50-70% yields on treatment with NaN02 in DMF or DMSO. Some of them are described precisely in vol 4 of Organic Synthesis. For example, 1,4-dinitrobutane is prepared in 41 -46% yield by the reaction of 1,4-diiodobutane with silver nitrite in diethyl ether.92b 1-Nitrooctane is prepared by the reaction with silver nitrite in 75-80% yield. The reaction of silver nitrite with secondary halides gives yields of nitroalkanes of about 15%, whereas with tertiary halides the yields are 0-5%.92c Ethyl a-nitrobutyrate is prepared by the reaction of ethyl a-bromobutyrate in 68-75% yield with sodium nitrite in DMF.92d Sodium nitrite is considerably more soluble in DMSO than in DMF as a consequence, with DMSO, much more concentrated solutions can be employed and this makes shorter reaction times possible.926... 

Annex III lays down the conditions of use for permitted preservatives and antioxidants, with lists of foods and maximum levels in each case. Part A lists the sorbates, benzoates and p-hydroxybenzoates, E 200-E 219 part B lists sulphur dioxide and the sulphites, E 220-E 228 part C lists other preservatives with their uses, including nisin, dimethyl dicarbonate and substances allowed for surface treatment of certain fruits, E 249 potassium nitrite, E 250 sodium nitrite, E 251 sodium nitrate and E 252 potassium nitrate, E 280-E 283 propionic acid and the propionates part D lists the antioxidants E 320 butylated hydroxyanisole (BHA), E 321 butylated hydroxytoluene (BHT), E 310 propyl gallate, E 311 octyl gallate, E 312 dodecyl gallate, E 315 eiythorbic acid and E 316 sodium erythorbate. 

Little Inc Rept (Ref 6, pp 81, 107 108), the prepn of the Potassium salt is described using Ter Meet s method, as modified by Jacobson (Ref 4). For this, to 1-cbloro-l-nitroethane (listed in Vol 3 of our Encycl, p C254-R) dissolved in methanol, was added at about 0° an aq soln of K nitrite. A short... 

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