Precautions for safe handling of peroxide and nitrogen oxide reactions

2.

(1) Reactions carried out in solvents are usually not dangerous

(2) The concentration of excess peroxide in the organic phase is often greater than that in water, and it is usually difficult to wash off the excess peroxide with water

Tests have proved that sodium sulfite or sodium bisulfite as the quencher is more effective than sodium thiosulfate or manganese dioxide

(3) Use water-moisturized starch potassium iodide test paper to test whether there is residual peroxide (or oxidant) in the organic layer.

3I ₂ + 60H ^- = 5I ^- + the IO _.

In this way, false negatives may be produced, which is easy to mislead people, thinking that the peroxide has been removed and performing misoperations, leading to danger

Figure 26-1 shows the solution containing the same concentration of peroxide.

Figure 26-1 Comparison of color development of starch potassium iodide test paper at different pH

(4) Pay attention to whether the solvent used in the reaction will be oxidized to peroxide by peroxide

(5) If the product is peroxide or nitrogen oxide, then these products may also be explosive (unless the safety index of peroxide ratio and explosive energy ratio is met), and its synthesis, post-treatment and separation and purification should not be concentrated (often For operations such as pressure distillation and vacuum evaporation), the best choice is to keep it in the solution and use it directly in the next step after extraction

In short, when the molecular weight of the compound with peroxy group or nitrogen group is less than 200, if the amount of material exceeds 3g, it cannot be heated and concentrated, let alone evaporated to dryness; the molecular weight is between 200-250 with peroxygen Groups or compounds with aminooxy groups should also be carefully considered

(6) When the product is peroxide or nitrogen oxide, the post-treatment is best combined with the next step of reaction, depending on what solvent it is, it can be extracted with the same hydrophobic solvent (such as dichloromethane , toluene, etc.

(7) When releasing the vacuum, do not use air directly, but use inert gas such as nitrogen or argon

The molecular weight of nitrogen oxides is usually gel-solid when the molecular weight is between 120 and 150, and more than 150 are solid