I want to prepare Methylamine Iodide following the reported procedure using Methyl amine and hydroiodic acid.While continuing with the procedure the solution need to be evaporated using a rotary evaporator and the precipitate is recovered .But when I was putting the solution in the Rotary Evaporator the solution didn't get evaporated.What could be the reason ?Although I applied all the required conditions.
Methylamine reacts ,as a base, with hydroiodic acid to form an acidic ionic salt called methylammmonium iodide as the equation shows:
CH3NH2 + HI(aq)→ CH3NH3+1 I-1(aq). This salt is quite stable solid (after careful evaporation of the little water that comes from the acid).
It is not easy to obtain H2N-CH2-I by reacting excess ammonia with CH3I since there will be SN2 mechanism which will furnish methylamine with I- getting out "it is a very good leaving group".
At standard conditions, methylamine is a gas that usually comes dissolved in water or in organic solvents such as ethanol or THF. If you are using an aqueous solution of methylamine (plus an aqueous solution of HI), maybe it might be hard for your rotary evaporator to remove water from that solution. Check the minimum pressure achieved by the pump of your rotary evaporator, and consider that you will need -ideally- less than 50 mbar to efficiently remove water without heating too much the solution.
If you are using organic solvents, you should not have problems to remove them with a rotary evaporator, but again, it will strongly depend of the solvent in question, the cooling water of the condenser and the potency of your pump.
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