1,1-diphenylethanol | Methyldiphenylcarbinol preparing from benzene

1,1-diphenylethanol is an alcohol compound. Two benzene groups are attatched to the same carbon which has -OH group also. 1,1-diphenylethanol is a benzene substituted alcohol compound.


In this tutorial, we learn followings with preparing of 1,1-diphenylethanol.

  • structure of 1,1-diphenylethanol
  • preparing grignard reagent from chlorobenzene
  • Preparing tertiary alcohol from grignard reagent and carboxylic acid chloride reaction


  • Derive 1,1-diphenylethanol from benzene using Grignard reagents

    Like aliphatic ethanols, 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 have 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 a 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.

    1,1-diphenylethanol structure

    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, taked the number one.

    1,1-diphenylethanol | 1,1-diphenyl-ethane-1-ol

    Prepare 1,1-diphenylethanol from benzene

    You can start your conversion from benzene and ethanol. Each step of benzene to 1,1-diphenylethanol is explained below.

    Preparing chlorobenzene

    Chlorobenzene is prepared by the reaction of benzene and chlorine gas ( Cl2 ) in the presence of AlCl3.

    Chlorobenzene and magenesium, dry ether reaction

    Next, chlorobenzene reacts with magnesium with dry ether and give grignard reagent (phenyl magnesium chloride) .


    Ethanol to ethanoic acid

    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+.


    Ethanoic acid to ethanoyl chloride

    Ethanoic acid (a carboxylic acid) reacts with PCl3 or PCl5 to give ethanoyl chloride. Ethanoyl chloride is a carboxyllic acid chloride compound.


    Grignard reagent and carboxylic acid chloride reaction

    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.


    Phenyl magnesium chloride (grignard reagent) and ethanoyl chloride reaction

    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.


    Benzene to 1,1-diphenylethanol

    benzene to 1,1-diphenylethanol


    Acidity of 1,1-diphenylethanol

    1,1-diphenylethanol is an tertiary alcohol. Acidity of 1,1-diphenylethanol is less than ethanol.