1,1-diphenylethanol is an alcohol compound with two phenyl groups (benzene). Two benzene groups are attached to the same carbon which has hydroxyl group also. 1,1-diphenylethanol is a benzene substituted alcohol compound. For the preparation of 1,1-diphenylethanol, we should only use benzene and ethanol as organic compounds.
In this tutorial, we learn followings with preparing of 1,1-diphenylethanol.
Like aliphatic ethanol, we can prepare aromatic alcohols. Here we try to make benzene substituted alcohol compound using grignard reagent. In this example, IUPAC name is given, then you know to draw the structure of molecule. We can understand, this compound is an alcohol because IUPAC name ends with ol part. Two benzene molecules are bonded to same carbon atom as substitutes (1,1-diphenyl). The root chain has two carbon atoms (eth). Also 1,1-diphenylethanol can be named as 1-Diphenyle-ethane-1-ol.
According to the IUPAC nomenclature, two phenyl groups are connected to the number one carbon atom of main chain. In the main chian, there are two carbon atoms with alcohol group. The carbon atom which hold the -OH group, takes the number one.
You can start your conversion from benzene and ethanol. Each step of benzene to 1,1-diphenylethanol is explained below.
Chlorobenzene is prepared by the reaction of benzene and chlorine gas ( Cl2 ) in the presence of anhydrous AlCl3.
This reaction is an electrophilic substitution reaction.
Next, chlorobenzene reacts with magnesium in dry dry ether medium and give grignard reagent (phenyl magnesium chloride) .
Ethanol is oxidized to ethanoic acid by strong oxidizing agent such as acidic potassium permanganate ( H+ / KMnO4 ). When oxidizing reaction is occurred purple colour of acidic potassium permanganate is reduced or become colourless because MnO4- is reduced to Mn2+.
When carboxylic acid chloride compound is treated with excess grignard reagent, two alkyl groups (in the grignard reagent) are added to the carboxylic acid chloride and forms tertiary alcohol when water is added.
It's required to substitute two alkyl groups from grignard reagent to carboxylic acid chloride to form tertiary alcohol. Therefore we have to add excess grignard reagent.
Finally grignard reagent and ethanoyl chloride are mixed together and add water. Two phenyl groups are added to the ethanoyl chloride molecule. It gives 1-diphenylethanol which is a tertiary alcohol.
1,1-diphenylethanol is an tertiary alcohol. Acidity of 1,1-diphenylethanol is less than ethanol.