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This is the answer to chapter 20, problem number 75 from the smith organic chemistry textbook.
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This problem tells us that a reaction of butane nitrile with methyl magnesium bromide, followed by treatment with aqueous acid, forms compound g.
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And so we're told that compound g has a molecular ion at m to z equals 86.
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And then we're given some ir and nmr data for g as well, and we're asked to come up with a structure for g.
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Okay, and so with an m to z of 86, so there's an oxygen in here, so that's going to account for 16, and so that leaves us with 70.
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And so i'm going to say that this is c5, so that's 5 carbon, so that's 60 mass units, h10, which would put us at 70 mass units, and then one oxygen.
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So that's going to get us all the way to 86.
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And so actually i'm going to rewrite that in green, so c5, h10o.
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And so i'll write everything that i'm doing in green to distinguish it.
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The stuff that i write in black is stuff that the problem will have given us.
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Okay, so c5h10o is a possible formula here.
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We have an ir peak at 1721.
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So that's consistent with a carbonyl.
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So carbon, carbon, double bond oxygen.
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Okay, and so we can calculate an hdi for this formula, c5h10o.
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So that's going to be 2 times 5 plus 2 minus 10.
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So that comes out to 2, all of that over 2.
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So we have an hdi of 1.
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And so this carbonyl makes sense.
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That would account for our 1 degree of unsaturation.
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So unfortunately, our nmr integrations are given to us in integration units.
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So we need to convert them to number of hydrogens, number of protons.
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And so the way that we do that is we add them all up.
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So we have 25 plus 17 plus 24 plus 17 for a total of 83.
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So we have 83 integration units in total.
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We have 10 hydrogens in our formula.
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And so we divide 83 by 10.
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And so 8 .3 integration units is going to be equal to one hydrogen.
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So then we just need to divide each of the individual units by 8 .3.
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So 25 divided by 8 .3 is roughly 3.
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24 divided by 8 .3 is also roughly 3.
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And then 17 divided by 8 .3 is roughly 2.
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Okay.
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And so now we can fill those numbers in for our nmr signals.
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So our triplet at 0 .9 ppm is going to be three hydrogens...