In a natural product synthesis, a chemist prepares a complex...

In a natural product synthesis, a chemist prepares a complex biological molecule entirely from nonbiological starting materials. The target molecules are often known to have some promise as therapeutic agents, and the organic reactions that are developed along the way benefit all chemists. The overall synthesis, however, requires many steps, so it is important to have the best possible percent yields at each step. What is the overall percent yield for such a synthesis that has 24 steps with an 80 percent yield at each step?

Key Concepts

Overall Percent Yield

Overall percent yield refers to the final efficiency of a multistep process, calculated by multiplying the fractional yields of each individual reaction step. When steps are sequential and independent, the small losses at each step compound, resulting in a significantly lower overall yield even if every step is moderately efficient.

Exponentiation in Yield Calculations

In calculating overall yield for a process with a constant percent yield per step, the yield is raised to the power of the number of steps. This exponential relation shows that even a high yield per individual reaction can lead to a very low overall yield when many steps are involved.

Importance of Yield Optimization

Maximizing the yield at each step is critical in multistep syntheses because the overall efficiency is highly sensitive to the performance of each individual reaction. Small improvements in each step can compound to produce a significantly greater overall yield, which is essential for the viability of complex synthetic processes.

Transcript

00:01 Alright, hello there.

00:02 Thanks for the question.

00:03 So this one's pretty pretty brief actually pretty interesting pretty easy.

00:08 So that's always nice to have some of these so what is the overall percent yield i'll just skip to the actual question part for such a synthesis that has 24 steps with an 80 % yield at each step.

00:20 So, you know, that's point eight you know going from one step to the next and we do it 0 .824 times so this is this is 0 .8 to the 24 all right, and then we'll convert it back to a percent but it's basically, you know if i have x and then i have a reaction where i make y but i only get 0 .8 and then i have to go and turn that into z and i only get 0 .8 again you can see how you would be multiplying the the 80 % you would be multiplying these percents it'd be multiplicative across each step.

00:57 And so you'd have to do that 24 times if there are 24 steps.

01:01 So real quick what is that point eight times or to the 24th? excuse me is point zero zero four seven two two and then we'll go back to percent right just times a hundred.

01:15 So i'm so silly.

01:19 Sorry there we go point four that's obvious i didn't need to plug that in but uh here here we caught me at a moment of unpreparation so, all right professional or unprofessional there it is.

01:35 It's answered and point four seven two two is is what you need for this.

01:41 All right.

01:41 Take care.

01:43 All right...

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