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 '''Nomenclature:'''
Alcohols are organic compounds that have the general formula; C<sub>n</sub>H<sub>2n+1</sub>OH. They are often recognised by the -OH group attached to the first [[Carbon|carbon]].


The Oxford English Dictionary defines an alcohol as a liquid with a number of properties such as flammability and highly volatile<ref>Oxford English Dictionary: Alcohol. 2017 [cited: 5/12/17] ; available from: https://en.oxforddictionaries.com/definition/alcohol</ref>, however chemically the term alcohol refers to a functional group. Alcohol is the IUPAC name for a molecule containing a hydroxyl group. When naming such a molecule, the prefix ''hydroxyl- ''or the suffix ''-ol'' is used. When using ''hydroxyl- ''the number is placed before the prefix to show the position of the hydroxyl group within the molecule. When''–ol&nbsp;''is used, it is placed before the suffix, interrupting the remainder of the word.<ref>Sanoma State University. Naming alcohols and phenols. 25 Aug 2017 [cited 5/12/17] Available from: https://chem.libretexts.org/LibreTexts/Athabasca_University/Chemistry_360%3A_Organic_Chemistry_II/Chapter_17%3A_Alcohols_and_Phenols/17.01_Naming_Alcohols_and_Phenols</ref>
=== Naming Alcohols  ===


Alcohols have the ending -ol, however when naming alcohols with more than one -OH there is now hydroxy added, between the number of the position of the extra -OH and then ending is now -anoic acid. If there are more than one -OH groups, then di, tri and tetra are used. Numbers are used between the stem and the -ol to show where the position of the -OH is in the [[Compound|compound]].


=== Alcohol Structures  ===


'''Colloquial Names:'''
There are 3 different types of alcohol structures. There is the primary structure, the secondary structure and the tertiary structure. The primary structure has one [[Alkyl group|alkyl group]] attached to the carbon, that holds the -OH group these alcohols are normally named; [[Methanol|Methanol]], [[Ethanol|Ethanol]], [[Propanol|Propanol]], [[Butanol|Butanol]] etc. The secondary structure has two alkyl groups attached to the carbon, that is holding the -OH group and the tertiary structure has three alkyl groups attached to the carbon, holding the -OH group. The secondary and the tertiary alcohols are named using numbers between the stem and -ol to show where the -OH group is. An example of a secondary alcohol is - Butan-2-ol and an example of a tertiary alcohol is - 2-methyl butane-2-ol.


There are a number of alcohols that are used commonly, and so the IUPAC names are not used. Common colloquialisms include wood alcohol, the common name for methanol and menthol, a colloquialism for a longer and far more complicated name that is not necessary for the majority of people (menthol is systematically called 2-(2-propyl)–5–methyl–cyclohexane–1–ol). <ref>R Eccles. Menthol and Related Cooling Compounds. Journal of Pharmacy and Pharmacology 1994; 46</ref>Alcohol has also become a colloquial name for the simple alcohol ethanol, which is the alcohol commonly found in intoxicating beverages. In a lab, the IUPAC systematic name as always used.
=== Reactions  ===


Primary and secondary alcohols undergo [[Oxidation|oxidation]]. Primary alcohols with the addition of [[Potassium dichromate|potassium dichromate]](VI) and dilute sulphuric acid, is converted to an [[Aldehyde|aldehyde]] which has the ending -CHO, when you warm it gently, this can then be distilled. Primary alcohols can then be further oxidised by using excess [[Potassium dichromate|potassium dichromate]](VI) and distilled sulphuric acid using heat under reflux and can be converted into a carboxylic acid which has the ending -COOH. In order to test that an acid is produced, sodium carbonate is added which will cause some fizzing and the production of [[carbon dioxide|carbon dioxide]] (CO<sub>2</sub>). Secondary alcohols can also be oxidised using acidified potassium dichromate(I), this will change the secondary alcohol into a ketone when you heat under reflux, ketones have the ending -one. These reactions always produce water. Tertiary alcohols cannot undergo oxidation using potassium dichromate(VI), as the carbon holding the -OH group has no hydrogen bonded to it. As well as being oxidised alcohols can also be dehydrated and be made into alkenes using concentrated sulphuric acid and warming it under reflux. Primary alcohols produce one product whilst secondary and tertiary alcohols produce two products that are E/Z isomers of the alkene made from the original alcohol<ref>Neil Goalby. 3.5 Alcohols. ( Online ); Citied 2017 December 5th. Available from: https://chemrevise.files.wordpress.com/2016/08/3-5-revision-guide-alcohols.pdf</ref>.


'''Types of alcohols:'''
=== References  ===


Alcohols can be vaguely defined into two categories – simple alcohols and higher alcohols. Simple alcohols are alcohols with up to four carbon atoms. They typically have few other functional groups, and so include alcohols such as methanol, ethanol and propan-1-ol.&nbsp;'''<ref>Chemguide. Introducing alcohols. October 2015 [cited 5/13/17]; available from: https://www.chemguide.co.uk/organicprops/alcohols/background.html</ref>'''
<references />
 
Higher alcohols are alcohols with four or more carbon atoms. They are often more complex and contain other functional groups or chemical structures such as rings and branches. These include alcohols such as phenol and 3 phenyl-propanol. <ref>Encyclopaedia Britannica - Leroy G. Wade. Alcohols. June 2017 [cited 5/12/17]; Available from: https://www.britannica.com/science/alcohol</ref><br>

Latest revision as of 16:22, 1 November 2018

Alcohols are organic compounds that have the general formula; CnH2n+1OH. They are often recognised by the -OH group attached to the first carbon.

Naming Alcohols

Alcohols have the ending -ol, however when naming alcohols with more than one -OH there is now hydroxy added, between the number of the position of the extra -OH and then ending is now -anoic acid. If there are more than one -OH groups, then di, tri and tetra are used. Numbers are used between the stem and the -ol to show where the position of the -OH is in the compound.

Alcohol Structures

There are 3 different types of alcohol structures. There is the primary structure, the secondary structure and the tertiary structure. The primary structure has one alkyl group attached to the carbon, that holds the -OH group these alcohols are normally named; Methanol, Ethanol, Propanol, Butanol etc. The secondary structure has two alkyl groups attached to the carbon, that is holding the -OH group and the tertiary structure has three alkyl groups attached to the carbon, holding the -OH group. The secondary and the tertiary alcohols are named using numbers between the stem and -ol to show where the -OH group is. An example of a secondary alcohol is - Butan-2-ol and an example of a tertiary alcohol is - 2-methyl butane-2-ol.

Reactions

Primary and secondary alcohols undergo oxidation. Primary alcohols with the addition of potassium dichromate(VI) and dilute sulphuric acid, is converted to an aldehyde which has the ending -CHO, when you warm it gently, this can then be distilled. Primary alcohols can then be further oxidised by using excess potassium dichromate(VI) and distilled sulphuric acid using heat under reflux and can be converted into a carboxylic acid which has the ending -COOH. In order to test that an acid is produced, sodium carbonate is added which will cause some fizzing and the production of carbon dioxide (CO2). Secondary alcohols can also be oxidised using acidified potassium dichromate(I), this will change the secondary alcohol into a ketone when you heat under reflux, ketones have the ending -one. These reactions always produce water. Tertiary alcohols cannot undergo oxidation using potassium dichromate(VI), as the carbon holding the -OH group has no hydrogen bonded to it. As well as being oxidised alcohols can also be dehydrated and be made into alkenes using concentrated sulphuric acid and warming it under reflux. Primary alcohols produce one product whilst secondary and tertiary alcohols produce two products that are E/Z isomers of the alkene made from the original alcohol[1].

References

  1. ↑ Neil Goalby. 3.5 Alcohols. ( Online ); Citied 2017 December 5th. Available from: https://chemrevise.files.wordpress.com/2016/08/3-5-revision-guide-alcohols.pdf
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