Application SN1 Reactions, Nitrosamines, and Cancer

a widely consumed canned meat in Alaska, Hawaii, and other parts of the United States, contains sodium nitrite. 

Nitrosamines can be formed when amines that occur naturally in food react with sodium nitrite, NaN02, a preservative added to meats such as ham, bacon, and hot dogs to inhibit the growth of Clostridium botulinum, a bacterium responsible for a lethal form of food poisoning. Nitrosamines are also formed in vivo in the gastrointestinal tract when bacteria in the body convert nitrates (NOs ) into nitrites (NO2), which then react with amines. 

The use of sodium nitrite as a preservative is a classic example of the often delicate balance between risk and benefit. On the one hand, there is an enormous benefit in reducing the prevalence of fatal toxins in meats by the addition of sodium nitrite. On the other, there is the potential risk that sodium nitrite may increase the level of nitrosamines in certain foods. Nitrites are still used as food additives, but the allowable level of nitrites in cured meats has been reduced. Debate continues on whether nitrite preservatives used at their current low levels actually pose a risk to the consumer. 

Given a particular starting material and nucleophile, how do we know whether a reaction occurs by the SnI or Sn2 mechanism Four factors are examined  

The most important factor in determining whether a reaction follows the SnI or Sn2 mechanism is the identity of the alkyl halide. 

---