Grignard Synthesis Of Triphenylmethanol Patrick
Grignard Synthesis of Triphenylmethanol
Aim
The aim of this experiment was to prepared Grignard reagent (phenylmagnesium bromide) from bromobenzene and magnesium, to use the reagent prepared to synthesise a tertiary alcohol (triphenylmethanol) by reacting reagent and ester (methyl benzoate), and the product formed is analyse by infrared spectroscopy (IR), melting point, thin layer chromatography (TLC), gas chromatography mass spectrum (GCMS) and finally Nuclear Magnetic Resonance spectroscopy.
Introduction
Formation of long hydrocarbon chain compound as becomes very useful in organic chemistry synthesis. In 1912, Victor Grignard a French chemist was awarded Nobel Prize in chemistry for discovery of organometallic compound known as Grignard reagent (Anon., 2009). Grignard reagent consists of carbons chain and a metal bonded together, the metal is usually magnesium. Due to electronegativity between magnesium and carbon, Mg is less electronegative than carbon. Therefore it partial positively charges and the carbon is partially negatively charge. Carbon is not stable therefore it is very reactive as it more nucleophilic. Nucleophiles are compounds negatively charged in other word positive charge loving that donate their pair of electrons to form a new bond. They can also be called Lewis bases as they accept proton from electrophilic species.
Grignard reagent can be simply prepared by redox reaction of magnesium metal and alkyl halide in dry diethyl ether solvent. In this experiment the alkyl halide use is bromobenzene, to form the reagent phenylmagnesium bromide.
Figure 1: reaction of Mg and bromobenzene.
Phenylmagnesium bromide was expected product of this reaction however there are some by-product such as biphenyl which is formed from the reagent prepared reacting with unreacted bromobenzene.
Figure 2: Biphenyl as by-product of the reaction
The reagent formed is very reactive capable of performing as a strong base and extremely strong nucleophile. Anhydride
Aim
The aim of this experiment was to prepared Grignard reagent (phenylmagnesium bromide) from bromobenzene and magnesium, to use the reagent prepared to synthesise a tertiary alcohol (triphenylmethanol) by reacting reagent and ester (methyl benzoate), and the product formed is analyse by infrared spectroscopy (IR), melting point, thin layer chromatography (TLC), gas chromatography mass spectrum (GCMS) and finally Nuclear Magnetic Resonance spectroscopy.
Introduction
Formation of long hydrocarbon chain compound as becomes very useful in organic chemistry synthesis. In 1912, Victor Grignard a French chemist was awarded Nobel Prize in chemistry for discovery of organometallic compound known as Grignard reagent (Anon., 2009). Grignard reagent consists of carbons chain and a metal bonded together, the metal is usually magnesium. Due to electronegativity between magnesium and carbon, Mg is less electronegative than carbon. Therefore it partial positively charges and the carbon is partially negatively charge. Carbon is not stable therefore it is very reactive as it more nucleophilic. Nucleophiles are compounds negatively charged in other word positive charge loving that donate their pair of electrons to form a new bond. They can also be called Lewis bases as they accept proton from electrophilic species.
Grignard reagent can be simply prepared by redox reaction of magnesium metal and alkyl halide in dry diethyl ether solvent. In this experiment the alkyl halide use is bromobenzene, to form the reagent phenylmagnesium bromide.
Figure 1: reaction of Mg and bromobenzene.
Phenylmagnesium bromide was expected product of this reaction however there are some by-product such as biphenyl which is formed from the reagent prepared reacting with unreacted bromobenzene.
Figure 2: Biphenyl as by-product of the reaction
The reagent formed is very reactive capable of performing as a strong base and extremely strong nucleophile. Anhydride