[Skiznibbler]

I'm having fun learning organic chem but trying to learn stereochemistry is driving me insane

For now I'll just settle for knowing what enantiomers are I won't get into diastereomers because I'll probably give myself a brain hemorage. Alright plane old enantiomers. I noticed its always l and d. I'll use the left hand and right hand example.

I know that my left hand and my right hand are chiral and are enantiomers of each other because they are non superimposable mirror images of each other. This is simply because the fingers are arranged differently in relation to the thumb on each hand. Therefore we have an l and a d enantiomer. What if I had 2 giant multi faced hands with 50 fingers and 20 thumbs? Would that mean there would be way more than 2 possible stereoisomers?

This is whats confusing the hell out of me. I noticed decent sized (not too big) compounds had only 2 stereoisomers. An l and a d enantiomer. If you had a highly complex molecule with lots of different heteroatoms and functional groups on it would that mean there could be loads of different possible stereoisomers? If so what would you call these steroisomers? Obviously not enantiomers because there would be alot more than just an l and a d version of it.

[nj_bartel]

It's the mirror image of the entire molecule.

[Yggdrasil]

You are absolutely correct.  For example, for a compound containing n stereocenters, you will have 2ⁿ stereoisomers.  A good example of this are the aldohexoses (http://en.wikipedia.org/wiki/Hexose#Aldohexoses) which have 4 stereocenters (in the straight chain form) and therefore 16 different stereoisomers (8 pairs of enantiomers).

[C6H8O7]

Sorry to answer your question with a question but this is something I haven't studied.What would be the type of job or field that stereochemistry would apply to? I kind of understand what you are saying but I'm curious as to what applications this is useful for.

[macman104]

You should learn stereochemistry if you take an first semester organic chemistry course.

[C6H8O7]

Oh wait I just checked my textbook.

The textbook uses stereochemistry in creating odors or scents such as alkyl halides or n-butyl bromide

The book im using is this one
http://www.amazon.com/Introduction-Organic-Laboratory-Techniques-Microscale/dp/0495016306

It briefly mentions it but in the chapter it doesn't really reinforce what its called so much as how it works.I still haven't made it to that part yet to be honest.

I still am curious as to the applications this type of chemistry would use besides odor synthesis.

[macman104]

I guess I'm not sure how your textbook "uses" stereochemistry in "creating" odors and scents.  Are you sure you aren't confusing two different terms?

That is an organic lab book, not really an organic chemistry "lecture" textbook.  A textbook should have a whole chapter on stereochemistry.

[Skiznibbler]

CH68O7 stereochemistry is real important in pharmacology. People have died in clinical trials because the scientist gave them a different stereoisomer of a compound they deemed safe. The l enantiomer of a compound might be medicinal but its d enantiomer could be toxic. Its also a good skill to know how to convert a d version of your compound into its l version and vice versa because they often have different reactive properties. I hardly know anything about it myself but I think in alot of compounds the l enantiomer has subtle differences in chemical properties to its d counterpart but usually barely noticable and alot of the time you'll have a mix of both l and d so they call that a racemic compound.

I'll be starting chemical and pharmaceutical sciences in university in 2 months so I want to give myself a head start. I can't wait. I dropped out of highschool when I was about 15 and never took anything seriously but about 2 years ago I decided I wanted to get into chemistry/pharmacology and I was lucky enough to get into college without a highschool diploma. I'll have no problem with chem or biology but I may have some trouble with math.

Is the math they do in the first year of chemistry in university usually real advanced? I have been outta school for so long its not gonna be easy I know that.

[spirochete]

CH68O7 stereochemistry is real important in pharmacology. People have died in clinical trials because the scientist gave them a different stereoisomer of a compound they deemed safe. The l enantiomer of a compound might be medicinal but its d enantiomer could be toxic. Its also a good skill to know how to convert a d version of your compound into its l version and vice versa because they often have different reactive properties. I hardly know anything about it myself but I think in alot of compounds the l enantiomer has subtle differences in chemical properties to its d counterpart but usually barely noticable and alot of the time you'll have a mix of both l and d so they call that a racemic compound.

To expand on this: enantiomers actually have identical physical properties, eg melting point, boiling point, and enthalpy of formation.  Enthalpy of formation is just a measure of the energy contained in all the bonds of the molecule.

What is different about entantiomers is how they interact with other chiral molecules.  You are correct that this is an example of a difference in chemical properties between enantiomers.  Chiral molecules being molecules with non-superimposable mirror images.    Another way to think about chirality is that a chiral molecule lacks a plane of symmetry. 

The way this relates to biology is that enzymes are almost always chiral, thus enantiomers often have completely different effects in living systems.  Here is a website with a brief introduction to structure property relationships including the importance of enantiomers in living systems: http://www.chem.umass.edu/people/samal/269/structureproperty.pdf

[C6H8O7]

You guys are awesome.Thanks a lot.

[C6H8O7]

I'll be starting chemical and pharmaceutical sciences in university in 2 months so I want to give myself a head start. I can't wait. I dropped out of highschool when I was about 15 and never took anything seriously but about 2 years ago I decided I wanted to get into chemistry/pharmacology and I was lucky enough to get into college without a highschool diploma. I'll have no problem with chem or biology but I may have some trouble with math.
Is the math they do in the first year of chemistry in university usually real advanced? I have been outta school for so long its not gonna be easy I know that.

I'm kinda in the same position although i'm waiting till winter.I bought my chem labbook as I think that might be what I want to major in.I have found I do better when I have a good understanding of the basics before I even start.

I scored in the top 5% in science on the ged and did pretty well in the rest of them at the age of 16.This made me decide to go more towards chem or I may switch to other sciences at some point.Im not the greatest with math either but I can still learn it if the teacher is good.I will probably pay for a tutor if I can't learn via the professors approach.

I might end up in glass manufacture for glassblowing.I'm already a flameworker and its very interesting how different metals are added to glass to give it its color and how they can change color depending on how you heat it.

Sorry to go OT everyone.

[azmanam]

If you had a highly complex molecule with lots of different heteroatoms and functional groups on it would that mean there could be loads of different possible stereoisomers? If so what would you call these steroisomers? Obviously not enantiomers

To answer your original question, that's a layman's definition of diastereomers.  I like to think of it this way:  map out the (R) and (S) nomenclature for each stereocenter for the 2 molecules.  Then go stereocenter by stereocenter.  If all of the stereocenters changed nomenclature (say, from (R) to (S)), then the compounds are enantiomers.  If some but not all of the stereocenters changed nomenclature, then the compounds are diastereomers.

Some-but-not-all stereocenters change = diastereomers
all stereocenters change = enantiomers.

The prototypical example is thalidomide (http://en.wikipedia.org/wiki/Thalidomide).  One enantiomer is used to treat morning sickness in pregnant women.  The other is a teratogen (causes birth defects).  Problem is, even if you administer the drug in enantiopure form, the stereocenter will racemize in the body to a racemic mixture - and the teratogenic properties persist.  They don't give thalidomide anymore.

Another interesting example is Prilosec (omeprazole) and Nexium (esomeprazole).  Prilosec (http://en.wikipedia.org/wiki/Prilosec) is a racemic compound widely used to tread acid reflux disease.  Turns out, one of the enantiomers is significantly better at treating the disease.  Thus by separating out the active enantiomer, the drug can be administered at half the dose with the same efficacy.  So they did that.  And they called it Nexium (http://en.wikipedia.org/wiki/Nexium).  They put the racemic prilosec over-the-counter and kept nexium by prescription only.

[Yggdrasil]

I'll be starting chemical and pharmaceutical sciences in university in 2 months so I want to give myself a head start. I can't wait. I dropped out of highschool when I was about 15 and never took anything seriously but about 2 years ago I decided I wanted to get into chemistry/pharmacology and I was lucky enough to get into college without a highschool diploma. I'll have no problem with chem or biology but I may have some trouble with math.

Is the math they do in the first year of chemistry in university usually real advanced? I have been outta school for so long its not gonna be easy I know that.

While this may not apply to all chemistry student, this is how math works for chemistry majors at my undergraduate university.  With regard to math, first year chemistry students generally take calculus in their first year.  A chemistry student should expect at least 2 years of math (calculus, multi-variable calculus, differential equations and linear algebra) which can be somewhat difficult courses.  The 1st year chemistry courses definitely require a good understanding of algebra and will also likely involve some calculus (or at least calculus can help your understanding along).  Introductory physics classes (taken in the 1st or 2nd year) will require a good understanding of your math courses (esp. all of your calculus and differential equations).  In terms of chemistry courses, general chemistry requires some math, organic requires almost none, but physical chemistry starts getting into some real, hardcore math (if you are interested in physical chemistry, I would definitely advise taking some advanced math courses).

[C6H8O7]

When I was a freshman I passed algebra but that was the last math course I really finished.I could probably pick it up to at least trigonometry before I enter college by doing self study (which I am pretty good at) but starting off with calculus might be too advanced for me to jump into.I'm probably going more towards the organic route at first anyways. To be completely honest I'm more afraid of  english 101 than anything else.I have never had an english class I enjoyed any part of.