Diazomethane Preparation Procedure

Diazomethane Preparation Procedure * This procedure is for preparing the diazomethane for DBP analysis

Supplies needed * Based on use of the small reactor Reagents  ~1 g MNNG (1-Methyl-3-nitro-1-nitrosoguanidine, 97%, Aldrich)  MQ water  6 ml MtBE (Methyl-tert Butyl Ether)  1 ml ~5N NaOH Equipment  Reaction chamber (large)  500 ml erlenmeyer flask (to hold reaction chamber)  800-1000 ml plastic beaker  ~3 L crushed ice  1 ml plastic syringe  25 gauge, 5/8” luer lock needle  ~25 ml erlenmeyer flask or beaker  Teflon tape  Small glass funnel

Precautions!!! * MNNG and the gas produced are very dangerous. Always perform in hood with proper personal protection equipment and training.

Apparatus Cap w/septa

O-ring

Holding Flask Reactor stem Reactor base

05/08/18 1 057ef20bbcfab75ab89e59adf90bcc6a.doc Procedure 1) Tilt reactor so hole in reactor stem is facing up. It is important to make sure all additions to the reactor stem do not go through the hole. 2) Add the MNNG to the base of the reactor stem up to the fill line (~1 g)

Reactor Stem

Fill line

3) Add ~1 ml MQ water to reactor stem to moisten the MNNG and firmly screw on cap w/ septa. 4) Add 6 ml MtBE to reactor base 5) Place reactor stem in the reactor base with O-ring sandwiched in between glass flange. Wrap Teflon tape around the reactor at the O-ring and clamp tightly. Wrap Teflon tape around the cap. 6) Prepare and ice bath in a 800 ml plastic beaker. Place reactor in ice bath and allow reactor to reach thermal equilibrium. Adding some water to the ice will increase the heat transfer. 7) Plunge ~25 gauge needle through septa in reactor stem. Add ~1 ml of NaOH very slowly in a drop wise fashion (until all MNNG is gone). [Reaction is Extremely Exothermic!]. Be sure to keep pressure on the syringe since significant pressure builds up inside reactor. Be sure to maintain good heat transfer to the ice bath. 8) Allow ~30 minutes for reaction completion while in the ice bath. The outside MtBE solution should turn a moderate or deep yellow. If this does not occur, the solution is no good. 9) Allow the pressure to slowly release by loosening the cap first. Transfer diazomethane to 25 ml erlenmeyer flask via small glass funnel. Keep the diazomethane cold and use as soon as possible after preparation. If bubbles form following addition of the diazomethane to the sample, then diazomethane solution is good.

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