Reduction involves increasing the number of carbon hydrogen bonds by adding hydrogen across a double or triple bond which results in an increase in electron density at the carbon atom. Organic functional groups containing double and triple bonds which undergo reduction are unsaturated. The reduction of the double bond by addition of hydrogen atoms results in the product being fully saturated. Metal hydride reducing agents that have different reactivities toward specific functional groups are commonly used in chemical reductions. There are challenges in synthetic organic chemistry to develop new reducing reagents that react with only one type of functional group in the presence of other reducible groups. The two most common metal hydrides
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The reduction of this ketone produces secondary alcohols. Sodium borohydride is often used in this process because it reacts more rapidly with the carbonyl group than with the solvent. In this experiment, the reduction of 9-fluorenone using sodium borohydride to give 9-fluorenol will be examined. This reaction involves the transfer of a hydride ion from borohydride ion to the electrophilic carbonyl carbon with the accompanying transfer of the electron deficient boron atom to the carbonyl oxygen.1 The reaction is shown below: 10 is 9-fluorenone, 11 is the intermediate borate salt, and 12 is 9-fluorenol. 2
Experimental
Before coming into the lab, a stoichiometry table was created with information for each reagent and product.
Table 1: Stoichiometry Table
Reagents Mass/Volume Molecular Weight (g/mol) Moles Mole Ratio
9-fluorenone 0.6 g 180.20 0.0033 2.5
NaBH4 0.05 g 37.83 0.0013 …show more content…
The product air-dried for about one week. After this time, the 9-fluorenol was recrystallized by a mixed solvent recrystallization4 using methanol and water over the steam table. The solution was cooled to room temperature and put in an ice-water bath for ten minutes. The crystals were collected and placed in the oven to dry for fifteen minutes. The product was weighed to calculate percent yield and its melting point was determined.5, 6 IR spectra of the starting material and the final product was obtained in order to be compared with those of authentic samples.1
Results
The initial amount of 9-fluorenone was 0.603 g. After completing the experiment, the product yield of 9-fluorenol was 0.313 g, which yielded 51.9% as seen in table 2. The melting point range of the product was 151.5°C – 153.5°C.
Table 2: Yield and Melting Point of 9-fluorenol
Theoretical Yield 0.603
The reduction of this ketone produces secondary alcohols. Sodium borohydride is often used in this process because it reacts more rapidly with the carbonyl group than with the solvent. In this experiment, the reduction of 9-fluorenone using sodium borohydride to give 9-fluorenol will be examined. This reaction involves the transfer of a hydride ion from borohydride ion to the electrophilic carbonyl carbon with the accompanying transfer of the electron deficient boron atom to the carbonyl oxygen.1 The reaction is shown below: 10 is 9-fluorenone, 11 is the intermediate borate salt, and 12 is 9-fluorenol. 2
Experimental
Before coming into the lab, a stoichiometry table was created with information for each reagent and product.
Table 1: Stoichiometry Table
Reagents Mass/Volume Molecular Weight (g/mol) Moles Mole Ratio
9-fluorenone 0.6 g 180.20 0.0033 2.5
NaBH4 0.05 g 37.83 0.0013 …show more content…
The product air-dried for about one week. After this time, the 9-fluorenol was recrystallized by a mixed solvent recrystallization4 using methanol and water over the steam table. The solution was cooled to room temperature and put in an ice-water bath for ten minutes. The crystals were collected and placed in the oven to dry for fifteen minutes. The product was weighed to calculate percent yield and its melting point was determined.5, 6 IR spectra of the starting material and the final product was obtained in order to be compared with those of authentic samples.1
Results
The initial amount of 9-fluorenone was 0.603 g. After completing the experiment, the product yield of 9-fluorenol was 0.313 g, which yielded 51.9% as seen in table 2. The melting point range of the product was 151.5°C – 153.5°C.
Table 2: Yield and Melting Point of 9-fluorenol
Theoretical Yield 0.603