[Pickard88]

hi, i was just wanting a bit of advice. i know i cannot expect to learn the intricacies of chemistry from a few posts on a forum but if anyone has any advice i would really appreciate it.
how to you formulate a reaction? say i had a precursor that i wanted to oxidize, and i have an oxidizing agent, how would i work out how much of said oxidizing agent to use?
as i said i don't expect to become an instant chemist and it may take years of university before getting to a point where it is possible to know how to go about it but thought you never know it may be simpler than i thought haha often synthesis are posted as the basics giving the precursor/reagents used and the basic process but no details in terms of quantities ect...
thankyou

[wildfyr]

Typically, we use molar equivalencies to work that problem out. 1 mol of oxidizing agent to 1 mol of precursor.

There are exceptions and more complicated systems, but that is the most general explanation.

[Pickard88]

ok wow that is more simle than i expected lol, does that just apply to oxidizing or is it the same for reductions/other reactions?

[wildfyr]

It depends a lot on your reagents. A single mole of lithium aluminum hydride contains 4 hydrides, so it can reduce something 4 times (potentially, as each hydride reacts from the core, the remaining ones are less reactive). However sodium hydride contains only 1 hydride, so it reacts 1 to 1.

Its really about moles of "reactive moieties" rather than mols of reagents per se. Putrecine has 2 equivalent reactive groups, so to acetylate both of them you would need 1 mol of putrecine and 2 moles of acetylating agent (like acetyl chloride).

[kriggy]

ok wow that is more simle than i expected lol, does that just apply to oxidizing or is it the same for reductions/other reactions?

More or less yes but there are other considerations as well.
For example, reducing the nitro group to amino group needs 6 electrons, therefore when using 2 electron donor like ZnCl2 you need at least 3 molar equivalents of it.
WHen reducing esters to alcohols by hydride reagents, the reaction goes stepwise: at first single hydride is added to the ester to yield aldehyde which then accepts another hydride and becomes an alcohol.

[Borek]

electron donor like ZnCl2

You've lost me. Not Zn?

[Pickard88]

youve lost me there as well i must say haha, how do you know which moieties of a reagent are reactive?

[hollytara]

This is where the literature is extremely useful.