Group 7 Alcohols

Today's Starter Quote When one door closes, another opens; but we often look so long and so regretfully upon the closed door that we do not see the one which has opened for us.” – Alexander Graham Bell

The simple way to think of alcohols is that there is a water molecule where the hydrogen at one of the termini is replaced by a carbon chain. The alcohol present in beverages is ethanol, which is the mildest depressant and narcotic poison of all alcohols. Other alcohols magnify this effect and are often added to ethanol in the lab to make it unpalatable. The addition of the OH group will drastically change the properties of the related hydrocarbon. This is due to the polarity of the molecule from a non-polar hydrocarbon, as well as the possibility of forming stable hydrogen bonds. Ethane is non-polar Mild intermolecular forces are easily broken

( 2010) Ethanol is polar and will have a σ+ H terminus at the OH group and a σ – oxygen atom adjacent to it. Water will have a smiliar structure, however due to its smaller size the molecule is more polarized. These σ+ and σ – ends are attracted to one another in solution. This creates a very strong network of hydrogen bonds. These networks are significantly more difficult to break. The result? The boiling point of ethane is –89 °C, while ethanol will boil at 78 °C!

In the IUPAC naming system, the OH functional group changes the suffix from 'ane' to 'anol' at the ending of the chain. The parent alkane is the longest chain that contains that OH group. CH 3 OHmethanol Highly toxic, leading to blindness and death CH 3 CH 2 OH ethanolUsed in beverages, vanishes, lacquers and perfumes CH 3 CH 2 CH 2 OH 1- propanol Solvent for waxes, found in brake fluid CH 3 CH(OH)CH 3 2- propanol (ispropanol, rubbing alcohol) Used in the manufacture of gums, oils and acetone

Classification of alcohols: Alcohols are categorized based on the type of carbon that they are attached to. Since carbon atoms have 4 bonds, the atom that has the OH can be attached to 1,2 or 3 alkyl groups as well. This creates primary, secondary and tertiary alcohols respectively. The classification is important for the types of reactions that each will undergo because the products are determined by the availability of H atoms in key positions. The Lucas test will allow us to determine the identity of each alcohol. The 3 ° alcohol reacts instantly, the 2 ° alcohol reacts slowly (6 minutes) and the 1 ° alcohol will not react. CH 3 CH 2 CH 2 CH 2 (OH)1- butanol primary alcohol CH 3 CH 2 CH(OH)CH 3 2-butanol secondary alcohol CH 3 C(CH 3 )(OH)CH 3 2-methyl-2-butanol tertiary alcohol

Creating Alcohols – Making Aldehydes and Ketones A hydration reaction is an addition reaction that adds the two components of water across a unit of unsaturation. The reaction often requires acid as a catalyst to break the water moecule into H + and OH -. The reaction may occur as : H 2 SO 4 Propene+water -->2-propanol The reverse reaction is an elimination (dehydration) reaction Markovnikov’s rule: ‘the rich get richer’ When adding a substance such as water to an unsaturated hydrocarbon. The hydrogen will add to the carbon which already has more carbons. This is why in the example above 2-propanol is formed much more readily than 1-propanol. Another example would include : 1-butene+hydrogen bromide 1-bromobutane