Sciencemadness Discussion Board - Ideas for beginning synthesis

Ideas for beginning synthesis

spirocycle - 29-9-2010 at 13:11

I'm very interested in organic chemistry, and I roughly know the basics.
I see all these cool projects you guys are doing, and I want to get started.
I have a reasonably large glass setup (bought it in bulk), and I want to get started.

Does anybody have any ideas for a basic organic synthesis that would be on the safer side?

bahamuth - 29-9-2010 at 13:36

One of the first things I made was iso-pentyl nitrite..., and was laughing like hell when I cleaned the glassware in hot water.., then came the pounding headache and the red blushing of the face and neck.

Anyway, not so safe considering the toxic NOx gases forming. But fun since I learned that a small, barely noticeable amount of volatile compound could have biological effects.

Do you have any chemicals? Which ones, maybe we can help from there...

spirocycle - 29-9-2010 at 13:55

I have a very generous chemistry teacher who will help me get any common lab chemical for legal purposes, except exceptionally toxic ones (nitric acid for one, but I can get that on my own)

edit:not to mention OTC chems
i have a ton of methanol and DCM especially

[Edited on 29-9-2010 by spirocycle]

entropy51 - 29-9-2010 at 14:26

Quote: Originally posted by spirocycle

Does anybody have any ideas for a basic organic synthesis that would be on the safer side?

Esters are good: ethyl acetate, methyl benzoate. Hydrolysis of esters are good: salicylic acid from aspirin or oil of wintergreen. Alkyl bromides are fairly safe if you have good ventilation. Preparation of formic acid from glycerol and oxalic acid is a nice OTC prep.

"Safe" is a relative term, it depends almost entirely on your degree of skill and availability of safety equipment, especially a hood and heating equipment that does not use a flame. Many preps that are dicey on a one mole scale are safe on a one gram scale.

Look through the organic lab manuals in the forum library and initially avoid preps involving bromine, ether, aniline, nitrations...you can work up to these later.

spirocycle - 29-9-2010 at 15:06

I've done a dozen or so esters already, and ill take a look at the alkyl bromides.
I do have a makeshift hotplate

the main question I have to ask about this is, how do I know if the reaction was a success?
I know I can use TLC to check for impurities, but without specialty equipment, how can I determine how much is impurities and how much is product?

entropy51 - 29-9-2010 at 16:02

Quote: Originally posted by spirocycle

the main question I have to ask about this is, how do I know if the reaction was a success?
I know I can use TLC to check for impurities, but without specialty equipment, how can I determine how much is impurities and how much is product?

Unless you have access to IR, NMR, MS and GC you're probably stuck in the same place as most of us: MP, BP, refractive index. The older texts describe combustion methods for C, H, O, and N but few people nowadays have the patience for the methods that Liebig and Gatterman used. Building a GC is not beyond the capabilities of many amateurs and would be a very nice project for a student of organic chemistry. I wouldn't be surprised if a GC could be found on ebay.

spirocycle - 29-9-2010 at 18:09

other than a thiele tube, how can I determine the mp/bp accurately?

DDTea - 29-9-2010 at 18:56

spiro: what you can do depends entirely on your knowledge of chemistry and your comfort with working in a lab environment.

As far as measuring melting points, look for an instrument called a "mel-temp." I don't remember who makes it. It's basically a glorified thiele tube, but it's what we used in our sophomore O Chem labs.

Try the sandmeyer reaction to synthesize some long, conjugated systems. I always thought that was a "cool" reaction because of the bright colors.

If you're not hell-bent on syntheses, try some natural product extractions. There's a lot to learn from that.

For characterizing your products, I've seen some surplus UV/Vis spectrophotometers on eBay for less than $100. It might be worthwhile to buy one.

Have you looked into the Journal of Chemical Education? There's a lot of good stuff in there. I'd suggest broadening your horizons though: although there are certainly awesome things in organic chemistry, if you get a good background in wet analytical techniques and some physical chemistry, you'll be able to return to O Chem with a lot of new ideas. For example: using lasers to monitor the growth of particles via Rayleigh and Mie scattering, and in turn, measure reaction rates

Basically, remember that chemistry is *extremely* interdisciplinary. Most successful chemists I know didn't *just* study chemistry, but also biology, physics, math, or engineering.

Check out some university course websites to see the experiments they're doing in their labs. That could get you a step ahead if you plan to study chemistry in college.

spirocycle - 29-9-2010 at 19:10

^I intend to double major in physics and chemistry
and I've used mel-temp in the lab, but I cant afford it for personal use

i checked out that reaction you mentioned, the sandmeyer reaction, it involved making aryl halides from diazonium salts, not long conjugated systems
am I missing something, or was that a typo?

Once I get my glassware in order I plan on extracting piperine from black pepper
do you think a simple A/B extraction will work for it?

DDTea - 29-9-2010 at 19:43

Whoops, that was a typo. I was thinking of azo coupling reactions from diazonium compounds, which produce extended conjugated systems with bright colors. It's a neat reaction for preparing dyes and indicators (e.g. methyl red).

spirocycle - 30-9-2010 at 10:32

what should I search for for those reactions?
is there a name, or starting compound it's known by?

DDTea - 30-9-2010 at 15:23

For diazonium coupling reactions, you first need to make a diazonium compound: basically, start with some derivative of aniline, and boil that with NaNO2 and HCl. The next step is the actual coupling reaction, where an activated aromatic compound undergoes electrophilic aromatic substitution, with the diazonium salt as the electrophile.

It's a fairly easy reaction and was the first reaction I did when I started working with a professor (however, the product he had me make was just about impossible to separate!). I did it under inert atmosphere, which was pretty easy: I put a septum over the boiling flask, and injected a syringe into the septum. I cut off the top of the syringe and had a balloon filled with argon over it.

However, I no longer do organic chemistry, so my knowledge of this stuff is starting to get rusty from disuse! Some of the other members on this forum probably have better knowledge of this than I do. But to get you started, read up on electrophilic aromatic substitution, the sandmeyer reaction, and azo coupling.

EDIT: This is my 666th post. Hail Satan! *slaughters a virgin goat*

[Edited on 9-30-10 by DDTea]

spirocycle - 30-9-2010 at 16:52

do you think the inert atmosphere is necessary for this?

entropy51 - 30-9-2010 at 17:16

Quote: Originally posted by spirocycle

I'm very interested in organic chemistry, and I roughly know the basics.

Quote: Originally posted by spirocycle

what should I search for for those reactions?
is there a name, or starting compound it's known by?

spirocycle, why not try a little reading in the many good organic lab manuals in the forum library? Try to find some areas of chemistry that appeal to you. It's all been written down by chemists much smarter than most of us here. It might be better to approach this in a more systematic way than just asking others what you should do, and I think it would be more satisfying to you.

I could suggest some dyes to synthesize, but this can be quite a messy undertaking for the beginning chemist.

[Edited on 1-10-2010 by entropy51]

Lambda-Eyde - 30-9-2010 at 17:40

Quote: Originally posted by DDTea

For diazonium coupling reactions, you first need to make a diazonium compound: basically, start with some derivative of aniline, and boil that with NaNO2 and HCl.

The reaction is kept near 0 °C, to slow down the reaction of the diazonium ion (Ar-N+≡N) with water, forming a phenol (Ar-OH) and N2.

[Edited on 1-10-2010 by Lambda-Eyde]

DDTea - 30-9-2010 at 17:44

If you use N2 as the inert gas, shouldn't that also inhibit the formation of a phenol by Le Chatalier's principle? (In fact, I may have used N2 as the inert gas--I really don't remember)

[Edited on 10-1-10 by DDTea]

mr.crow - 30-9-2010 at 18:08

Quote: Originally posted by DDTea

If you use N2 as the inert gas, shouldn't that also inhibit the formation of a phenol by Le Chatalier's principle? (In fact, I may have used N2 as the inert gas--I really don't remember)

[Edited on 10-1-10 by DDTea]

Only for equilibrium reactions, this one is one way only

zed - 1-10-2010 at 17:26

Make sure you are ready to rumble, before working with anilines.

Many are poisonous. Some, are very poisonous.

spirocycle - 3-10-2010 at 09:59

I can work outside, wearing a Finnish army surplus gas-mask ( and gloves obviously)
do you think that is enough protection?

DDTea - 4-10-2010 at 11:27

Quote: Originally posted by spirocycle

I can work outside, wearing a Finnish army surplus gas-mask ( and gloves obviously)
do you think that is enough protection?

That represents flawed logic. Personal protective equipment should only be used in a lab setting where engineering controls (e.g.: a fume hood) cannot reduce risk sufficiently. Lab coats and goggles are generally the standard, but things like respirators ought not to be used as a primary means of protection.

The issue is that, even though you might be protecting yourself, you could be exposing others or the environment. What you should do is a risk assessment for the reaction you're doing. The way I learned to do this: search the MSDS for every chemical you're using in a particular procedure and note the primary hazards associated with them. There may be some chemicals, especially reaction products, where no risk assessment has been done; for those, you just have to be careful.

If, from your risk assessment, you find that you cannot work with them without some kind of exposure to yourself, others, or the environment, you really shouldn't go further. A sign of chemical maturity is knowing what you are able (or unable) to do safely.