Nucleophilic Hydride Lab
Abstract: The purpose of this laboratory is to convert benzophenone to diphenylmethanol. This was done by using sodium borohydride to reduce benzophenone. The product was then crystalized from hexanes then using the melting point and IR testing it was possible to characterize it. The melting point range was…
Introduction:
This lab is possible because of oxidation and reduction reactions. In organic chemistry oxidation is the loss of electron density around a carbon, while reduction is an increase in electron density around a carbon. More electronegative atoms such chlorine have a strong affinity for electrons while conversely low electronegative atoms have a low affinity for electrons. This unequal affinity for electrons causes an unequal …show more content…
Nucleophilic hydride is unstable by itself so it must be used through a hydride reagent such a NaBH4 or LiAlH4. The hydrogen is more electronegative than boron and aluminum giving it a negative charge. This causes the hydrogen to act like a hydride. This is important because it causes it causes it to be selective. A hydride has a negative charge so it will attack the positive carbon in a carbonyl group. This makes it more useful in synthesis reactions because if a molecule has a carbonyl group and carbon-carbon double bond, it will only attack the polar carbonyl group. LiAlH4 is much more reactive than NaBH4 because Al is more electronegative than boron which forms a stronger dipole making hydrogen more negative making it more nucleophilic. As explained both NaBH4 and LiAlH4 perform the same task, but because of LiAlH4’s higher reactivity they are used in different situations. NaBH4 can be used in alcoholic solvent while LiAlH4 can’t be because it will deprotonate and produce H2. Also, LiAlH4 can reduce ketones, aldehydes, carboxylic acids as well as esters. In contrast, NaBH4’s lower reactivity causes it only effective at reducing ketones, and aldehydes. In this lab NaBH4 will be used, an example of such a reaction using NaBH4 as a reducing agent …show more content…
Figure 5
(Note: the reduction is followed by the protonation of oxygen, this will be discussed during the discussion)
Reagent Table:
Chemical Name Structure Molecular
Formula Molecular Weight (g/mol) Amount Used Density (g/ml) Melting Point (°C) Boiling Point (°C)
Introduction:
This lab is possible because of oxidation and reduction reactions. In organic chemistry oxidation is the loss of electron density around a carbon, while reduction is an increase in electron density around a carbon. More electronegative atoms such chlorine have a strong affinity for electrons while conversely low electronegative atoms have a low affinity for electrons. This unequal affinity for electrons causes an unequal …show more content…
Nucleophilic hydride is unstable by itself so it must be used through a hydride reagent such a NaBH4 or LiAlH4. The hydrogen is more electronegative than boron and aluminum giving it a negative charge. This causes the hydrogen to act like a hydride. This is important because it causes it causes it to be selective. A hydride has a negative charge so it will attack the positive carbon in a carbonyl group. This makes it more useful in synthesis reactions because if a molecule has a carbonyl group and carbon-carbon double bond, it will only attack the polar carbonyl group. LiAlH4 is much more reactive than NaBH4 because Al is more electronegative than boron which forms a stronger dipole making hydrogen more negative making it more nucleophilic. As explained both NaBH4 and LiAlH4 perform the same task, but because of LiAlH4’s higher reactivity they are used in different situations. NaBH4 can be used in alcoholic solvent while LiAlH4 can’t be because it will deprotonate and produce H2. Also, LiAlH4 can reduce ketones, aldehydes, carboxylic acids as well as esters. In contrast, NaBH4’s lower reactivity causes it only effective at reducing ketones, and aldehydes. In this lab NaBH4 will be used, an example of such a reaction using NaBH4 as a reducing agent …show more content…
Figure 5
(Note: the reduction is followed by the protonation of oxygen, this will be discussed during the discussion)
Reagent Table:
Chemical Name Structure Molecular
Formula Molecular Weight (g/mol) Amount Used Density (g/ml) Melting Point (°C) Boiling Point (°C)