CHEM 1406 Concept Review: Intro to Organic Chemistry

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Organic Chemistry:  The study of compounds whose molecules contain carbon.

Alkanes:  Compounds composed of only carbon and hydrogen which have only single bonds.

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Carbon will almost always have 4 bonds.  This causes carbon atoms that contain only single bonds to have a tetrahedral shape.

 

Complete Structural Formula:  A representation of a compound that shows all of the atoms & bonds.

Condensed Structural Formula:  A representation of a compound that shows the atoms arranged in the order that they are connected.  Either no bonds or only carbon-carbon bonds are shown.

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Cycloalkanes:  alkanes where the carbons are connected in a ring

Examples:  1406 Ch 11 img 4.jpg

 

 

 

Alkanes with substituents

Substituent:  A branch attached to a longer carbon chain.  Branches can occur on alkanes of more than 4 carbons.  Branches can be in many different positions on the longest carbon chain.

(See next page for a list of common substituents and their names.)

Structural Isomers:  Molecules that have the same molecular formula but different bonding arrangements.

 

 

Naming Organic Compounds

The IUPAC (International Union of Pure and Applied Chemistry) naming system involves naming compounds systematically according their characteristics, the most important of which are:

A.  The length of the longest carbon chain.

B.  Which functional group or groups are present in the molecule.

C.  The presence of any branches (substituents) off of the longest carbon chain.

 

The general format of naming is as follows:
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Steps to naming an alkane

  1. Find the longest continuous chain of carbon atoms, and use the name of this chain (see table below) as the base name.
  2. Number the carbon atoms in the longest chain, beginning with the end nearest to a substituent.
  3. Name each substituent.
  4. Begin the name of each substituent with the number of the carbon atom (on the longest chain) to which it is bonded. Be sure to put a dash (-) between numbers and letters.
  5. When two or more substituents are present, list them in alphabetical order.
    (The presence of two or more substituents of the same kind is indicated by the prefixes di-,tri-,tetra-,penta-, and so forth. The prefixes are ignored in determining the alphabetical order of the substituents.  The numbers indicated for multiple substituents of the same type should be separated by commas.)

          First Ten Straight-Chain Alkanes
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Combustion Reactions:  Rapid reactions that produce a flame.  Generally, they will usually involve a hydrocarbon (CxHy) reacting with oxygen (O2) to produce water (H2O) and carbon dioxide (CO2).

General Form:     LaTeX: C_xH_y+O_2\:\longrightarrow\:CO_2+H_2OCxHy+O2⟶CO2+H2O                 Example:    LaTeX: C_3H_8\left(g\right)+5O_2\left(g\right)\:\longrightarrow\:3CO_2\left(g\right)+4H_2O\left(l\right)C3H8(g)+5O2(g)⟶3CO2(g)+4H2O(l)

 

Functional Group:  An arrangement of atoms within a molecule that is responsible for giving that molecule its characteristic reactivity and properties.  Functional groups are the centers of reactivity in an organic molecule.

(For more info on specific functional groups, see the handout Functional Groups available online or in the SLC)