Chemistry

Chemistry of Organic Compounds that contain Oxygen



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Organic chemistry of oxygen bearing carbon centers are alcohols and ethers in addition to carboxylic acids.  Peroxides can also be organic but usually inorganic such as hydrogen peroxide.  A well known example of alcohol is ethanol.  This compound finds uses in alcohol and the beer industry. 

Chemically speaking, alcohols are organic compounds which have high boiling points due to the existence of hydrogen bonding between neigbouring hydroxyl groups.  Alcohols are a reactive group of chemicals if we compare them with aliphatic hydrocarbons, which bear no heteroatom or a substituent. 

A useful method to prepare ethanol in particular and alcohols in general is to react alkylbromide with OH-group.  Alcohols on the other hand can be converted to many other organic compounds depending on the starting alcohol and the reagent it reacts with.  Primary alcohols are the least complicated chemically from all other alcohols. 

The OH-group in alcohols is not a good leaving group but can be made a good leaving group by treating the alcohol with tosylchloride for example which is a good leaving group.  Alcohols can be converted to the more reactive alkylchloride by treating the alcohol with the chloride ion source thionylchloride. 

Ethanol is important clinically due to its way of metabolism inside the body.  It is metabolized inside the body to acetaldehyde using alcohol dehydrogenase.  In addition the aldehyde is further metabolized to the acid using aldehyde dehydrogenase. 

The other interesting group of organic compounds that bear oxygen are the ketones and aldehydes.  Ketones and aldehydes are organic compounds with carbon to oxygen double bonds.  Ketones are also reactive like alcohols but to a lesser extent.  Ketones can be carcinogenic if ingested in large quantities due to the formation of imines or shiff bases with DNA bases amines.  The double bond in ketones is polarizable which gives it its characteristic reactivity.  

Ketones can be prepared from alcohols by oxidation of the hydroxyl group using an appropriate reagent such as PCC or pyridinium chlorochromate.  The chemistry of ketones is widespread.  Clinically significant is the reaction of ketones and aldehydes with amines of DNA bases.  This reaction is important because it forms imines or shiff bases which causes mutagenesis or cancer. 

Ketones can be reduced back to the alcohol using an appropriate reducing agent such as LiAlH4 or NaBH4.  Due to their characteristics ketones can be used as solvents for chemical reactions. 


The other type of organic chemicals that bear oxygen are the ether group.  Ethers differ from alcohols by the lack of the hydroxyl group in the latter compound.  Ethers have low boiling points due to the low dipole moment that they have.  They are inert to basic conditions.  For this reason they are sometimes used as solvents for specific reactions. 

Ethers are potential peroxides if left in atmospheric oxygen.  Under acidic conditions ethers oxygen is cleaved giving products depending on the counter ion and the reaction conditions.  A famous ether that is used worldwide in chemical labs is THF or tetrahydrofuran.  It is used as a solvent for many reactions.  This compound must be kept under an inert atmosphere of argon due to the potential formation of peroxides, which can be explosives.     

Organic acids are the last group of compounds bearing oxygen that are discussed here.  They are relatively strong acids due to the resonance stabilized conjugate ion.  Acids can be prepared from the acid chloride by hydrolysis with OH-ions.  They have a high boiling point relative to ethers and ketones.  Certain acids are present in the body and participate in metabolic reactions such as the krebs cycle.  

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