[Johte]

I'm frustrated, post-doc is useless, and NotVoodoo doesn't have much....

How do you take what you learned in sophomore lab class and translate to the research level?

For instance, do you take 25-30 g silica / 1 g crude product literally? If it took more solvent than I thought to dilute my sample do I pick the wider column to thin the band? Building on the last question do I need to increase the amount of silica ( to increase length ) to counter the now shorter/wider column.

While the answers to these questions would be helpful I would much rather be "led to the water" so that I may continually to progress on my own. My other reseource, The O. Chem Lab Survival Manual, 7th ed. doesn't have the detail I am looking for either.

[MOTOBALL]

1.  Re-crystallization of the crude is preferable to chromatographic purification in terms of time reqd./solvent volume reqd. etc !!!!

2.  If you have to run a silica gel column, then a long, narrow column is required.  Depending on the complexity of the crude rxn. product, 100 mg of crude per 25 gm silica gel may be more appropriate. 

3.  If you have just started preparative org. chem., A copy of Vogel's "Practical Organic Chemistry", published by Longmans would be worth its weight in gold !

Good Luck.

[TheUnassuming]

As much as you might not want to hear it, to get better at running columns you will need to run more columns.  Nothing will substitute for that.
Until you get enough experience to eyeball how much silica you need, measuring the mass is always a good idea.  People have different preferences as far as short and fat vs tall and skinny columns.  I and the others in the lab seem to prefer columns that have a length:width ratio of ~3:1.  Longer columns will start to get too wide of a band and shorter columns tend to not get the resolution I want.  With this ratio I can typically separate compounds that are "snowman'ing" on TLC.   
Play with the different ratios and see if one works better in your hands than others. 
Depending on what compounds you are working with, crystallization can be good as well.  Though more often than not when working with small molecules (especially ones you don't already have a crystallization protocol for) a column is much faster.  Once proficient you can run a column in 30-60min with out problem which you will be hard pressed to do when crystallizing.

[Elan]

I agree with "TheUnassuming", practice makes all the difference. The accumulation of minor factors are the difference between a seasoned veteran chemist's work and an undergrad at the start of his/her journey.

That said, this advice echos in my mind every time I run a column:

"Columns are won and lost on the load."

My mentor's mentor said that - I don't know his name.

[Dan]

"Columns are won and lost on the load."

So very true.

For instance, do you take 25-30 g silica / 1 g crude product literally?

No. Use more for a tougher separation, you can get away with less for an easy one.

If it took more solvent than I thought to dilute my sample do I pick the wider column to thin the band?

Do you mean dilute or dissolve? If you accidentally used more solvent than necessary, then you should concentrate the sample and start again. If the minimum volume required to dissolve the crude is too much for the column size, then you could use a larger column but that's probably not the best approach. A better approach is to preadsorb the crude onto a supporting matrix (silica, Celite etc.) and dry load the sample. Measure an amount of dry supporting material that is about 5% the volume of the column, tip it into  solution of the crude and concentrate. This should give a free flowing powder that you can tip onto the top of your column. If the crude/support mixture is sticky or lumpy, redissolve it, add a bit more of the supporting material and concentrate again. The total volume of the dry load should not exceed 10% of the total column volume (unless the separation is extremely easy).

Another alternative is to use a different load solvent - one in which the crude is more soluble. You need to make sure that the solvent is appropriate and will not drag your material too much on the first flush. TLC your crude using your proposed load solvent as the mobile phase, if the compound of interest stays close to the baseline you are good to go. Toluene, DCM and chloroform are usually good candidates.