newbee ? about calculating % yields

[nitrous351]

Hi, SWIM just wanted to know the formula for calculating %yield of MDMA from isosafrole. SWIM knows that % yield = actual yield/ theoretical yield x 100%. He also knows that calculating theoretical yield deals with moles of product and stoichiometric coefficients, but he does not know the balanced equation of the process (since there are so many reactions involved). Could somebee please post an equation to plug some numbers into (SWIM knows the moles of isosafrole and MDMA.HCl, but he needs the stoichiometry of the equation)??  he thanks you all in advance peace

[Relux]

The % yeild is found by comparing the moles of limiting reactant with the moles of the product. When it comes to MDMA, your limiting reagent should be isosafrol. You find the moles that you started with by dividing the grams by the molecular weight (but I think you knew that). Ok, now about the "stoichiometry". For every molocule of isosafrole you will get a molocule of MDMA, theoretically. so the stoichiometry is 1xisosafrole--->1xMDMA, and just about as simple as it gets. So, with 100% yeild, you would end up with as many moles of mdma as you had of isosafrol. Multiply this theoretical molar yeild by the molecular weight of MDMA to get the theoretical gram yield.
The closest I can come to an equation to give you is this:
(gIsosafrole)x(1moleIso/162.19gIso)x(229.71gMDMA*HCl/1molIso)=theoretical gram yield of MDMA
That is: (gIso)x1.4163=Theor.gMDMA*HCl
Now take the number of grams that you actually got and divide them by this number, then multiply by 100 and there is your percent yield.

[politoxicomania]

M (Molar weight [g/mol]) = m (masse in gramms)  /   n (quatity of molecules in mol)

[xbnmx]

Create a balanced equation of your synthesis to MDMA and then use a mole ratio to find the theoretical yeild of your reaction.  Next, divide your actual yeild by the theoretical yeild to find your percent yeild.  Hope this helps!