Hello, I have posted this on the vespiary and reddit and have gotten no help. This is a copy and paste from the reddit post. I don't know if there's something I'm missing but I will pay for help at this point.
The PyCC intermediate is made by the bisulfite method, crystallizing overnight in the fridge and melting around 27c which is close enough to literature value.
The grignard reagent is made with reagent grade bromobenzene and dried thf, it also decomposes with addition of water.
PyCC in thf is added dropwise to the grignard reagent in thf which produces some bubbles and is then refluxed for 3 hours. Everything looks fine at this point, but I have tried this bullshit 3 times now and can't get any product.
A quench mixture is made with ammonium chloride and water, the reaction mix added dropwise which creates blobs of what I assume are magnesium salts which dissolve after further addition of ammonium chloride and water.
The clear, slightly basic mixture is extracted with toluene twice and then an amount of concentrated hcl is added equimolar to the amount of predicted product. Azeotropic distillation is performed until only a yellow toluene goop is left and what little crystallizes upon addition of acetone is inactive.
Where in my workup am I going wrong? Do I need to do an acid base before I do azeotropic distillation? I am 99% certain this workup is the problem because all previous steps and reagents perform as expected. I don't have hbr and literally the only thing I can think left to try is quenching the mixture with hcl rather than ammonium chloride.
Edit: not sure how important this is but none of this was done on ice, the addition of PyCC was added to the grignard after the magnesium was all dissolved and taken off heat. The addition of this to the quench solution was done after sitting at room temp for 15 minutes after the 3 hour reflux. But there was no crazy reaction either time so I don't see the need for doing it on ice
Edit edit: next run going, put in the freezer for an hour before quenching which was done with only ice and ammonium chloride. Made even more basic with dilute naoh and extracted with toluene. Dean stark rather than distillation now, thf came off first and now waiting for the hcl to be pulled off. Still open to any suggestions
Edit edit edit: has nothing to do with ice temps. Still fucking nothing
The PyCC intermediate is made by the bisulfite method, crystallizing overnight in the fridge and melting around 27c which is close enough to literature value.
The grignard reagent is made with reagent grade bromobenzene and dried thf, it also decomposes with addition of water.
PyCC in thf is added dropwise to the grignard reagent in thf which produces some bubbles and is then refluxed for 3 hours. Everything looks fine at this point, but I have tried this bullshit 3 times now and can't get any product.
A quench mixture is made with ammonium chloride and water, the reaction mix added dropwise which creates blobs of what I assume are magnesium salts which dissolve after further addition of ammonium chloride and water.
The clear, slightly basic mixture is extracted with toluene twice and then an amount of concentrated hcl is added equimolar to the amount of predicted product. Azeotropic distillation is performed until only a yellow toluene goop is left and what little crystallizes upon addition of acetone is inactive.
Where in my workup am I going wrong? Do I need to do an acid base before I do azeotropic distillation? I am 99% certain this workup is the problem because all previous steps and reagents perform as expected. I don't have hbr and literally the only thing I can think left to try is quenching the mixture with hcl rather than ammonium chloride.
Edit: not sure how important this is but none of this was done on ice, the addition of PyCC was added to the grignard after the magnesium was all dissolved and taken off heat. The addition of this to the quench solution was done after sitting at room temp for 15 minutes after the 3 hour reflux. But there was no crazy reaction either time so I don't see the need for doing it on ice
Edit edit: next run going, put in the freezer for an hour before quenching which was done with only ice and ammonium chloride. Made even more basic with dilute naoh and extracted with toluene. Dean stark rather than distillation now, thf came off first and now waiting for the hcl to be pulled off. Still open to any suggestions
Edit edit edit: has nothing to do with ice temps. Still fucking nothing
