[JoeyBob]

Can someone please explain why/how I went wrong and how the correct mechanism works with these reagents? I think I mess up with the grignard reaction but i dont know how.

[chenbeier]

You missing the alkyl or aryl from the Grignard.

[clarkstill]

I don't see any obvious problems here - you've given a skeletal drawing of the methyl group in MeMgBr right? I guess being pedantic you should draw the product as OMgBr rather than as an alkoxide. Why do you think there is something wrong with your scheme?

[mjc123]

The acetyl group already contains a methyl; after adding MeMgBr you should get -CMe₂OH.

[clarkstill]

Wow - I must have written my answer before my morning coffee! mjc is of course correct

[JoeyBob]

The acetyl group already contains a methyl; after adding MeMgBr you should get -CMe₂OH.

That makes sense, but It's still not the right answer. I suppose I should have provided the answer, but I didn't think I'd need to. You're suppose to get this from doing the reagents in the order I did.

[JoeyBob]

Wow - I must have written my answer before my morning coffee! mjc is of course correct

I agree that I should get that. But the answer using the same reagents in the same order is actually this?

[ch3mist]

That last step of the synthetic sequence you drew depicts heating in aqueous acid, which implies more than just a simple acidic aqueous workup. Under those conditions, the tertiary alcohol undergoes dehydration via E1 elimination mechanism to afford the alkene product you've shown.

[JoeyBob]

So like this mechanism? I forgot the NH2, but just pretend it's there.

[mjc123]

Yes, but you need to be more careful with your drawing so you don't make the 2-propenyl group look like a t-butyl group!
There are chemical drawing software packages available, some of them free. If you can't do that, I suggest drawing it freehand on paper and posting a photo, rather than trying to draw it in Paint or whatever you're using. It just isn't clear.

[JoeyBob]

Yes, but you need to be more careful with your drawing so you don't make the 2-propenyl group look like a t-butyl group!
There are chemical drawing software packages available, some of them free. If you can't do that, I suggest drawing it freehand on paper and posting a photo, rather than trying to draw it in Paint or whatever you're using. It just isn't clear.

Yeah I wanted to get pymol a while back but it looked too complicated to download.

[hypervalent_iodine]

Yes, but you need to be more careful with your drawing so you don't make the 2-propenyl group look like a t-butyl group!
There are chemical drawing software packages available, some of them free. If you can't do that, I suggest drawing it freehand on paper and posting a photo, rather than trying to draw it in Paint or whatever you're using. It just isn't clear.

Yeah I wanted to get pymol a while back but it looked too complicated to download.

Pymol isn't really useful for this (although it's really not that complicated to download, you just have to go through a couple of extra registration steps). I believe ChemSketch and Marvin Sketch are free? If you are through a university, you should also check to see if they have a licence for ChemDraw that you can access. If not, there is a free web version: https://chemdrawdirect.perkinelmer.cloud/js/sample/index.html

[JoeyBob]

Yes, but you need to be more careful with your drawing so you don't make the 2-propenyl group look like a t-butyl group!
There are chemical drawing software packages available, some of them free. If you can't do that, I suggest drawing it freehand on paper and posting a photo, rather than trying to draw it in Paint or whatever you're using. It just isn't clear.

Yeah I wanted to get pymol a while back but it looked too complicated to download.

Pymol isn't really useful for this (although it's really not that complicated to download, you just have to go through a couple of extra registration steps). I believe ChemSketch and Marvin Sketch are free? If you are through a university, you should also check to see if they have a licence for ChemDraw that you can access. If not, there is a free web version: https://chemdrawdirect.perkinelmer.cloud/js/sample/index.html

I've had to use chemdraw before. It isn't really useful for me because drawing out mechanisms on paper or, in this case, using paint, is way faster.

[hypervalent_iodine]

Practice is key. Regardless, I would suggest that speediness is no substitute for clarity and quality.