Organic chemistry

Introduction

Organic chemistry is the chemistry that studies not only compounds in living things but everything that is carbon-based. Any carbon-based compound is an organic compound even if it’s natural or synthetic. The organic chemistry studies the way the carbon atoms can be arranged in molecules to form different things. The study of these compounds is very important due to the fact that many things in our everyday life are organic compounds for instance food, plastics, fuel, clothes and many other materials.

The electron configuration for Carbon is [He] 2s2 2p2. The carbon atom is said to be tetravalent because it has four valence electrons and therefore having the four electrons available to form covalent bonds to achieve the octet rule. The atom also presents the concatenation property and it makes it able to form bonds with other carbon atoms. The carbon atom is the only element whose hybridization (When atomic orbitals mix to form new atomic orbitals) can be: sp3, sp2, or sp.

Molecular formulas are used to represent which element is present and how many atoms for each. For instance we can see the molecular formulas for ascorbic acid and butane respectively.

• C6H8O6

• C4H10

Structural formulas are quite useful because in molecular formulas you cannot see the order in which the atoms are bonded. In structural formulas it is possible to observe in a more graphic way the bonds in a compound since the bonds are represented through lines connecting the atoms. For example here are two structural formulas. Both ethanol and dimethyl ether have the same molecular formula (C2H6O) but the bonds are ordered differently which makes them be different substances.

Ethanol

Condensed formula is a good and efficient way to make a formula. Molecular formulas are not as precise as structural formulas, but structural formulas take too much space and if needed digitally they can be hard to obtain. To solve this problem condensed formulas combine both of the above formulas.

• CH3-O-CH3 Dimethyl ether

• CH3-CH2-OH Ethanol

Petroleum comes from the deterioration of fossils over several years. The composition of petroleum may vary depending on where it was taken from, but it is mainly Hydrogen and Carbon. According to chemistry.about.com an approximate to the ratio of the elements in the composition of petroleum is as follows.

1. Carbon - 83 to 87%

2. Hydrogen - 10 to 14%

3. Nitrogen - 0.1 to 2%

4. Oxygen - 0.05 to 1.5%

5. Sulfur - 0.05 to 6.0%

6. Metals - < 0.1%

Petroleum refining is the process through which petroleum goes through to transform it into products. This process is called fractional distillation, in this process the petroleum is separated to get the useful material.

Some of the products of the refining process are

• petroleum gas used as a fuel in heating appliances and vehicles

• gasoline used as car fuel

• kerosene fuel, in cooking and many other appliances

• heating oil used as a fuel for furnaces or boilers in buildings

• lubricating oil used to reduce friction between objects

A list of the main refineries in Mexico

• Salamanca Refinery

• Reynosa Refinery

• Tula Refinery

• Ciudad Madero Refinery

• Minatitlan Refinery

• Cadereyta Refinery

• Salina Cruz Refinery

Petrochemistry is enormously important in our daily life because most of the things we use very day were made from materials discovered through petrochemistry. If in one day we did not use anything that involved petrochemistry our life would be extremely different.

Alkanes

The simplest organic compounds are hydrocarbons. Hydrocarbons contain only two elements, hydrogen and carbon. A saturated hydrocarbon or alkane is a hydrocarbon in which all of the carbon-carbon bonds are single bonds. Each carbon atom forms four bonds and each hydrogen forms a single bond to a carbon.

Straight Chain Alkanes

The general formula for an alkane is CnH2n+2 where n is the number of carbon atoms in the molecule. There are two ways of writing a condensed structural formula. For example, butane may be written as CH3CH2CH2CH3 or CH3(CH2)2CH3.

Branched Alkanes

Branched substituents are numbered starting from the carbon of the substituent attached to the parent chain. From this carbon, count the number of carbons in the longest chain of the substituent. The substituent is named as an alkyl group based on the number of carbons in this chain.

Numbering of the substituent chain starts from the carbon attached to the parent chain.

The entire name of the branched substituent is placed in parentheses, preceded by a number indicating which parent-chain carbon it joins.

Cyclic Alkanes

The parent name is determined by the number of carbons in the largest ring (e.g., cycloalkane such as cyclohexane).

In the case where the ring is attached to a chain containing additional carbons, the ring is considered to be a substituent on the chain. A substituted ring that is a substituent on something else is named using the rules for branched alkanes.

When two rings are attached to each other, the larger ring is the parent and the smaller is a cycloalkyl substituent.

The carbons of the ring are numbered such that the substituents are given the lowest possible numbers.

Haloalkanes

Also known as alkyl halides, are a group of chemical compounds comprised of an alkane with one or more hydrogens replaced by a halogen atom. The halogens we will be concerned with are fluorine, chlorine, bromine, and iodine.

Physical Properties

As we will see, there is a fairly large distinction between the structural and physical properties of haloalkanes and the structural and physical properties of alkanes. As mentioned above, the structural differences are due to the replacement of one or more hydrogens with a halogen atom. The differences in physical properties are a result of factors such as electronegativity, bond length, bond strength, and molecular size.

Ethane: C2H6, H3CCH3

Octane : C8H18, structural formula CH3(CH2)6CH3, CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH3

Pentane: C5H12, CH2-CH-CH2-CH2-CH3,

Alkenes

Alkenes are a family of hydrocarbons (compounds containing carbon and hydrogen only) containing a carbon-carbon double bond.

Physical properties of the alkenes

The boiling point of each alkene is very similar to that of the alkane with the same number of carbon atoms. Ethene, propene and the various

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