[a_ht]

How does one invent a new molecule so that, on paper, it has desired properties. What do I need to know to get started?

[Mitch]

minimum organic chemistry.

[movies]

It's very difficult to predict the properties that a molecule will have before you actually make it.  Most pharmaceutical research is based on little more than a couple of leads and a lot of work.  They typically find a structural motif that gives a desired effect and then vary substituents all over the molecule to try to optimize the effect.  Sometimes they don't really have any idea how the molecule is interacting with proteins, etc. in the body.

[constant thinker]

A lot of discoveries in chemistry are either accidental or through following other people research. Atleast that's what I've inferred from reading things.

[Mitch]

"accidental" being used very loosely.

[mike]

Combinatorial chemistry may be worth researching, it was quite popular a while back and is still used today.

[movies]

A lot of reactions were discovered as "side reactions" to other know reactions and then optimized under slightly different conditions to favor the different reaction pathway.  It's hard to do because most chemists just dismiss the side products of reactions as junk and don't give them a second thought.

[a_ht]

Ill just make a polymer! Where can I find detailed reference information about bonding properties of "bonds??" - Photoreactivity, bonding strengh, what makes a molecule soluble, volatile, whats gives polymer a particular shape, etc. How can I find that type of information?

[mike]

Ill just make a polymer

what type of polymer?

[a_ht]

There are different types? One composed of 2 isomers. 1 isomer breaks when subjected to UV light. The other isomer is reserved for future properties.

[mike]

http://en.wikipedia.org/wiki/Polymer

 

[Mitch]

organic photreactivity is very interesting. Any text in physical organic chemistry should go over it. Look for the pericyclic reactions chapter.

[movies]

There are tons of different types of polymers.  Their properties vary not only based on their molecular structure, but also based on many other superstructural and external factors.  The poly-dispersity (the range of polymer sizes, usually by MW), the addition of non-polymerized external molecules (so-called plasticizers) which are used to tune the polymer for hardness, flexibility, etc., and the overall denisty of the polymer are also important.  You can also have copolymers where you have polymerized two different monomer units into one polymer.  These can be either alternating monomer units, random, or block copolymers where the two (or more) units are polymerized in separate "blocks" along the larger polymer.  You can also make cyclic polymers where you make one huge polymer ring; these often have different properties than linear polymers of similar size.  Cross-linked polymers are very important.  I cross-linked polymers, linear polymer chains are attached to one another through chemical bonds.  These are often very rigid polymers.

On a molecular level, the stereochemistry of nearby atoms can have large effects on the macroscopic behavior of the polymer.  Generally you can have either random stereochemical arrays, alternating R/S, or single stereochemistry (e.g. R only) polymers.  Some of the macroscopic properties of polymers can be predicted based on known polymers with similar structures, but again there is a lot of trial and error involved in finding the kind of polymer you want!

[a_ht]

This weekend, I want to sit down, grab a pen and sheet of paper and start drawing my molecule (writing the little symbols and the OH, H-C=C-H thingy). I need to know where I can find the numbers. Are there no books or online resources that publish the properties of different isomers? And what their properties are when combined? What do you guys use in the industry, the physic and chemistry handbook doesn't seem to give all these details. Are there no reference material that you use? All I can find on the net is introductory and tutorial material... I need the next step, which is accurate relevant information about the known isomers and their properties.

[Mitch]

The whole thing about chemistry is that the product is very different then the some of its parts. So, you can't add 2 fragments together and know the chemistry of the combined fragment. That being said people in the field can readily do this because they are experienced with this stuff. Like I said in my first post, if you read an undergraduate organic chemistry book from start to finish you would have the knowledge to make the first attempt at something interesting.