Crosby Chem Reference Sheet

Organic Chemistry – not a comprehensive document. Is based on the number of carbons. prefixes: meth-, eth-, prop-, but-, pent-, hex-, hep-, oct-...... # carbons: 1 2 3 4 5 6 7 All organic chemistry is based on a hydrocarbon chain, consisting of carbon/hydrogen Functional groups:

Alcohol – not an acidic group! Compounds end in -ol. e.g: ethanol.

Carbonyl – found in sugars. If either of the R groups is a hydrogen, the functional group is an aldehyde (compound name ends in -hyde). Else, it's a ketone (pictured), compound name ending in an -one.

Amine – is basic, draws protons towards itself. Compound name ends in -amine.

Ester – may be a fragrant molecule. Compound name ends in -ate.

Ethers – not to be confused with esters.

Thiols – name ends with -thiol.

Carboxyl – acidic functional group. Donates the last H since the O-H bond is very weak.

Always name the compound going in the same direction along the carbon chain. Do not, I repeat, DO NOT start from one end, and then switch to the other. If a H atom is not drawn, look at the carbon chain. If there are free spaces, it usually means a hydrogen is implied. Count the number of carbons, account for numbers of electrons. If the diagram isn't an ion, there should be no free spaces. WARNING: there might be electron pairs. Write the # of the carbon the functional group is attached to + how many functional groups. e.g: 3,2 dimethylpentane means a pentane chain with TWO methyl groups on the 2nd and 3rd carbons. The cyclo- form of anything will be a hydrocarbon ring. All functional groups hang off of it. Isomers Isomers are compounds with the same molecular formula but different structural formulae. Enantiomers are two stereoisomers that are mirror images of each other(non-superimposable). Stereoisomers are molecules that have the same molecular formula and sequence of bonded atoms . The term chiral is used to describe an object that is non-superposable on its mirror image. Chiral carbons are carbons that are • sp3-hybridized • have four different groups attached to the carbon atom.

Carbon Bonding

Alkene – double bonded carbon. Ethene is a linear alkene.

Alkane – single bonded carbon. Non polar. Methane is an alkane.

Alkyne – triple bond between carbons. Ethyne is an alkyne. Cis- and trans-

Cis-butene. Notice that the first and last carbon are on the same side of the C=C cluster.

Trans-butene. First and last carbons are on opposite sides of the C=C cluster.

Molecular orbital (MO) theory uses a linear combination of atomic orbitals to form molecular orbitals which cover the whole molecule. Two types of orbitals: Sigma and pi Sigma orbitals are divided into two sigma and sigma*(anti-bonding). Occurs along the bond axis. Pi orbitals are also pi and pi*, A double bond is a sigma bond and a pi bond, a triple bond is a sigma and two pi bonds. Because they meet head-on, the interaction between the 2pz orbitals is stronger than the interaction between the 2px or 2py orbitals. As a result, the 2p orbital lies at a lower energy than the 2p* orbital lies at higher energy than the x* and y* orbitals.

x and

y orbitals, and the

Hybrid orbitals are a concept to explain molecular geometries.

Quick Reference: Orbitals combine to produce Single bonded tetrahedral: methane. Sp3 hybridized. Ethene: sp2 hybridized ethyne: sp hybridized. Quick Reference:

Bonding order=

bonding electrons – antibonding electrons 2

Overview of hybridization: The carbon in methane has only two unpaired electrons. However, forming four bonds releases more energy than two bonds. Therefore, the carbon 'bumps' up an electron to a 2p orbital. The now half-filled p orbitals and the s orbital merge to form 4 sp3 orbitals – (mixing a s and 3 p orbitals). The 1s orbital of the hydrogen now mixes with the hybrid orbitals to form the sigma bond in CH4 In Ethene, the carbon bumps the electron to the p orbital, but only two p orbitals merge with the s to form sp2. The last p orbital is left for the carbons to bond with each other (C2H6) Sources: Wikipedia, chem.purdue.edu. All rights belong to respective owners. Images: upload.wikimedia.org, chem.purdue.edu my text: Attribution-Noncommercial-Share Alike 3.0