Eiteiou

Question: Which of the following types of functional groups react with Grignard reagents: alkenes; terminal alkynes; non-terminal alkynes; alcohols; alkanes; tertiary amines; secondary amines? I know that grignard reagents are strong bases and nucleophiles, and so they will react with alcohols, terminal alkynes, and secondary amines definitely. Alkenes, alkanes, and non-terminal alkynes will not react, right? The one I'm not sure about is the tertiary amine...I have not seen an example of a grignard reagent reacting with one but I don't see why not...too crowded, charge distribution, I'm not sure?? Is my thinking correct on this?? Thanks!

Here is my assignment: Draw resonance structures to show in which position nitrobenzene will nitrate to form dinitrobenzene. I know that nitro groups are meta-directing, so the product will be m-dinitrobenzene. So do you just draw an intermediate carbocation with the charge in the meta position? If that's the case, where is the resonance? Would I show the charge being in the ortho, para, and meta positions but then indicate that the meta position is the most stable and therefore where substitution will occur?? I'm not fishing for just the answer, I want to make sure I understand this right, so any advice is helpful, Thank You!

Here is my assignment: Drawresonance structures to show in which position nitrobenzene will nitrate toform dinitrobenzene. I know that nitro groups are meta-directing, so the product will be m-dinitrobenzene. So do you just draw an intermediate carbocation with the charge in the meta position? If that's the case, where is the resonance? Would I show the charge being in the ortho, para, and meta positions but then indicate that the meta position is the most stable and therefore where substitution will occur?? Any advice is helpful, thank you!

Wonderful, thank you for your reply and for the resource. So now i understand the formation of the dichromate ion. One more question, if you have a minute...the H+ that catalyzes the oxidation reaction, is this from the acetic acid as well? Also, just to confirm this, the cr4+ containing molecule would be HCrO3- in the final product, but is unstable, so would breakdown into cr3+ and water, correct? Thanks again!

Hello! Can anyone help me in drawing out a mechanism for the oxidation of cyclohexanol to cyclohexanone? I will attach my work below, my main problems are, 1. Before adding the sodium dichromate dihydrate to the alcohol, we mix it with the acetic acid. Does this activate it, making it an oxidizing agent? How does that work? Does the acetic acid attract sodium ions, giving the poly atomic ion dichromate? If so, how does dichromate get to HCrO4^-? Does it react with the water from the sodium dichromate being a dihydrate? I'm not sure of the function of those water molecules. My next question, 2. Is where does the proton come from in turning the alcohol into a chromate ester? Is this the hydrogen dissociated from acetic acid when it picked up sodium, or from the dihydrate? I'm also unsure of the specific mechanism here. My last and most important question, 3. Is, I know the reaction will change from orange to green when oxidation is complete because the chromium ion begins as Cr6+ and is then reduced (as it is the oxidizing agent) but the lab manual says that Cr3+ is responsible for the green, however the reaction ends with HCrO3^- which would give the chromium ion an oxidation number of 4, not 3...any guidance would be great!

Going to be performing this lab experiment next week and I'm trying to figure out the mechanism just for a better understanding. The textbook does not offer a detailed enough mechanism for my liking. Let me explain the procedure and I'll mention my gaps of understanding as I go...First we are mixing acetic acid with sodium dichromate dihydrate. I'm assuming that this activates the dichromate to make it an oxidizing agent, but the transfer of atoms confuses me... Does the acetic acid attract the sodium ions to make the poly atomic ion dichromate cr2o7^2-? In order to do that it must lose a hydrogen, does it lose it to water molecules to form hydronium ions, or just dissociate and form free protons in the mix? Either way I know that dichromate ^2- must form. The next step in the reaction mechanism would be water plus the dichromate ion to form hcro4^-. Again, here I don't understand how that step works, where do the three oxygens go?After this we add the dichromate mixture to cyclohexanol to form a chromate ester and water. This reaction will then involve a water molecule acting as a base, taking a hydrogen off the carbonic carbon, so then the electrons from that bond make the carbonyl bond to the oxygen, while the chromate ester is eliminated. This step must be the actual oxidation, because here is where the ketone forms. However, my next issue is that the products, which are the cyclohexanone, hydronium ion, and hcro3^- confuse me. Specifically the hcro3^-, because I know we started with a cr6+ chromium, which appears. Orange, but the lab book says the reaction will finish green because of a cr3+ chromium, but the oxidation number on the chromium atom in hcro3^- is cr4+ is it not?