Everything You Never Wanted to Know About Nitriles
Nomenclature - I'm going to start with nomenclature because I'm not too solid on it. I prefer IUPAC, but my teacher likes both common and IUPAC and that makes me a sad panda. Basically, you add a -nitrile suffix to the name. If it's a substituate, you use cyano- as a prefix.
Pause for a second: Apparently spellcheck hates chemistry.
They are named similarly to COOH, you remove the -ic or -oic acid from the COOH name and ad -onitrile. If it's a ring, -carbonitrile. I *think* that the priority is similar to COOH, but I'm not positive.
Random properties of Nitriles - No H bonds, but they do have dipole moments, so they have high-ish BPs. They are electrophiles. This is about it cause, hell, there's not a lot here really.
Preparation of Nitriles -
CN- Rxn with 1 or 2 degree Alkyl Halide - More of that "halides sure are important for tacking bits together" thing. The reagents are NaCN/THF. As a hint, when you see CN it's a pretty safe bet that it's getting added to the molecule, you just have to figure out where and how that reaction effects the other groups around it. In this case it replaces the halide with a CN. Note: these are triple bonded to each other, so it's likely you'll see that a lot. I just can't draw it on tumblr. Also, this particular rxn is Sn2. Later, when we see what nitriles do, you'll realize that this is a really good reaction for increasing the carbon chain by one.
Dehydration of a 1 degreen amide - An amide is a special kind of molecule. It looks like a COOH, but in place of the OH it has an NH2. This makes the NH2 group very reactive, and it's good for making chains of things with N in the middle. However, if we dehydrate this molecule using SOCl2 @ 0C, it dehydrates it. It steals the O, and the two Hs off of the Nitrogen, which allows that C to bond three times to the N. This is NOT good for extending the carbon chain. Both of these reactions are useful though, but this one is more generally used because there are fewer problems with steric hinderance.
3. Reactions of nitriles
Mostly, these are all Nu. First: Hydrolysis: Nitrile --> COOH. We've already seen this in our COOH creation entry, but just to revisit. The reactants can be: H3O+, NaOH, or H2O. These are pretty reactive, it doesn't take much to make them do things. This has an amide intermediate, but the presence of all that reagent makes the reaction push past the amide despite its relative stability. In the end the Nitrogen is removed and the OOH is added to the place where the N was, which makes the COOH.
Reduction of a nitrile to an amine - The reagents that you'll want to look for here is your basic staple reducing agent: LiAlH4, Ether/H2O. BTW, the ether isn't necessary to write, it's a solvent. Your teacher may leave it out an just expect you to know the reaction happens in ether. Lots of 'em do. Mine just adds it into the reaction conditions over the arrow with the reagents. Anyway, This adds a bunch of H's, which turns the nitrile into an amine. Which...you know, makes sense. Basically just add H's to all the bonds if you see a reducing agent and a nitrile and you'll be fine.
Nitrile w/ organometallic reagent --> ketone - "Organometallic reagent" is just another way of saying the grignard. See? Told you to learn about that, it's everywhere. If you get through ochem without learning about it, you probably failed ochem. x.x If you add a grignard to a nitrile it DOES NOT make an OH, it makes a ketone. So the alkane group is still added and the N removed (in the form of ammonia.), but it creates a C=O, not an OH as per usual. This is similar to the carboxylation of a grignard reaction. If your teacher asks you how to make ketones, this is a valid answer. It never makes aldehydes though.
Alright, that's it for Nitriles. It's a small bit that makes a big difference. They are used for lots of stuff. So although there's not a lot of material, they're still fairly high-yield things to know. That means lots of bang for the buck. :)
Ok, after a long day of studying (I've been doing virtually nothing else today, as you may have been able to tell. ;P~~), I'm showering and sleeping. Tomorrow during the day I'm probably going to do some physics posts, and some ochem either after I get home from my physics final or if I have time after studying for physics. Physics comes way easier to me than this does, so I will probably have less to say about it.
Nite tumblr!