Historically - organic molecules could only be produced by living things - "vitalism" - the intervention of a "vital force" was necessary for the synthesis of an organic compound.
-could not be produced in a beaker
-similar to what we now think of with the commercial term "organic"
Of course, many organic compounds can be produced in the laboratory:
Ex: honey that a bee makes (glucose) can be made in the laboratory
What's in a name?
Often when one sees a "chemical name", it is assumed to be artificial, not "organic"
The above is simply the systematic name for the compound glucose.
Organic compounds are those based primarily on Carbon. Such compounds dominate our lives. The majority of "chemical names" we see are organic compounds. For instance, check out this ingredients list:
a-Terpinolene, Ethyl butanoate, 3-Carene, Ethyl acetate, Ethyl 2-butenoate, a-Terpinene, a-Thujene, Dimethyl sulfide, Limonene, b-Phellandrene, Myrcene, p-Cymen-8-ol, b-Caryophyllene, cis-3-Hexene-1-ol, hexadecyl acetate, 5-Butyldihydro-3H-2-furanone, trans-2-hexenal, Ethyl tetradeconaoate, a-Humulene, Ssabinene, 2-Carene, Camphene, Ethyl octanoate, 4-Isopropenyl-1-methylbenzene 1-Hexanol, g-terpinene, hexanal, Ethyl hexadecanoate, a-Copaene, Hexadecanal, Ethanol, Ethyl propionate, Dihydro-5-hexyl-3H-2-furanone, Carveol, Geranial, Ethyl decanoate, Furfural, Butyl acetate, Methyl butanoate, 2,3, Pentanedione, 1,1, diethoxyethane, pentadecanal, Butyl formate, 1-Butanol, 5-Methylfurfural, Ethyl dodecanoate, 2-Acetylfuran, 2 Methyl-1-butanol, 4-Methylacetophenoen, Acetaldehyde, Cyclohexane
From: The extraordinary chemistry of ordinary things, C.H. Snyder
ingredients list above is a partial list for the Mango
Bonding to carbon
1. organic compounds are generally made up of carbon bonded to other non-metals - covalent bonding is expected
2. Lewis structure of carbon important in understanding bonding
To satisfy octet rule, carbon will often bond to four other things
Remember methane CH4
Bonds get as far as part as possible - tetrahedral
hydrogen can only form a single bond with another atom such as carbon
A closer look at the bonding in methane:
Covalent bonds represent the sharing of electrons - we drew pictures of orbitals on atoms (s,p,d,f) - can we imagine how they are shared to form bonds??
For H2, this is simple:
How about for methane: CH4
Electron configuration of C = 1s22s22p2
If we imagine the valence p and s orbitals, it is hard to see how we get tetrahedral bonding because these orbitals do not point to the corners of a tetrahedron.
Answer: orbital hybridization - the s and p orbitals merge to form four new orbital called sp3 hybrids. The sp3 nomenclature indicates that the orbitals formed are 25% in s-character and 75% in p-character. The four sp3 orbitals formed point to the corners of a tetrahedron.
The bonding in methane can then be seen as the overlap of the s-orbitals of hydrogen and the sp3 hybrid orbitals of carbon. Remember, angle between bonds is 109.5o
dominant elements in organic molecules are carbon and hydrogen:
molecules which contain only carbon and hydrogen are called hydrocarbons:
Note: Study Fig 11.4 to better understand the ways in which structural formulas are drawn.
All of the above compounds containing all C-C single bonds are called alkanes, which have the general forumula:
mineral oil: C16 - C20
petroleum jelly and waxes: >C20 - C25
Shapes of alkanes - tetrahedra bound together leads to zig/zag shapes.
Different "conformations" are possible due to rotations about C-C bonds (see fig 11.5 in book and see pdb models above). Compare two conformations of butane: the "anti" conformation, and the "eclipsed" conformation.
Alkanes and organic molecules in general can exist as isomers
isomers - molecules that have the same chemical composition (chemical formula) but different molecular structures
ex. C4H10 - can arrange 4 carbons and 10 hydrogens in more than one way and still have the octet rule satisfied - 2 isomers
ex: pentane C5H12 - 3 isomers
C10H22 has 75 isomers
C20H44 has 366,319 isomers