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1 ORGANIC CHEMISTRY 307 LECTURE NOTES II R. Boikess A. Overall Organization and Systematization There are16 million organic compounds and more every day. We must have a way to systematize so that we can learn and communicate. a. Remember why there are so many compounds (C-C bonds and chains). So one focus is to describe the carbon skeleton, which consists of a “main” chain of C atoms with various additional C atoms or groups of C atoms (smaller chains) attached at various points. b. Think of it as a “connect the dots puzzle” with “branches” allowed. Pre-Draw a big grid of dots and then connect. Show for 3 dots, 4 dots, 5 dots and 6 dots. Each different pattern corresponds to a different carbon skeleton, which is the starting point for describing and naming all organic compounds. Note it’s the pattern of attachment that counts, how many dots a given dot is connected to, not how we draw it straight, zig-zag, or bent. Show how right angle bend doesn’t matter for propane and butane etc. But show (and we will return to) rings. For 10 dots there are 75 ways, for 25 dots almost 36.8 million ways (not counting rings). That’s why this is a whole-year course. c. How do we go from a carbon skeleton to a compound? Every C must have 4 bonds. Most carbons in most compounds get to 4 bonds by bearing the requisite number of hydrogens. Introduce 1 , 2 , and 3 carbons , related to the number of C’s to which a given C is attached. Again, go from Kekule to condensed formulas and to condensed formulas with parentheses. [CH 3 (CH 2 ) 4 CH 3 and CH 3 C(C 2 H 5 ) 2 CH 3 ] Go from dots to skeletal structures. (omit terminal dots (carbons), bend lines so that a vertex of an angle represents a dot. (carbon) as does the end of a line. Show for propane, butane and isobutane Note branches off the main chain. Constitutional isomers, discuss.
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2 c. Most org cpds have at least one C that gets to 4 in some other way than maximum H’s. One obvious way is with a multiple (double or triple) bond, which uses 2 carbons. Show also that it can’t happen in some structures (neopentane) and there can be no triple bonds in many others. Discuss pentavalent carbon, which is impossible under ordinary conditions. d. Another way is to use atoms other than H. These are most commonly (in order) O, N, X. S, and P. Generally there aren’t many compared to the number of C’s and H’s. e. Any part of the molecule that is something other than a C bonded to other C’s by single bonds and to H’s is called a functional group. The chemical behavior and to some extent the physical behavior of the molecule is determined primarily (but not entirely) by the functional groups. Most chemical change takes place at the functional groups. So we are going to focus on functional groups, their chemistry their interconversion, their preparation, an their properties in general. f. But the carbon skeleton is also very important. Ex: methanol and
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This note was uploaded on 04/04/2008 for the course CHEM 307 taught by Professor Several during the Spring '08 term at Rutgers.

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