Scheme For Alkaline Hydrolysis Biology Essay

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A combination of Isophthalonitrile, 5M sodium hydroxide, and dioxane was placed in a round-bottom flask equipped with a magnetic follower. A reflux apparatus was then set up with the use of a paraffin oil bath. The reflux was then stabilized at 90 oC and the mixture was allowed to reflux overnight. Ammonia was liberated as a result of the condensation reaction. The absence of ammonia from the adduct was then tested via TLC. Petroleum ether/ ethyl acetate (1:1) was utilized as the mobile phase and Isophthalonitrile was used as a reference. No ammonia was observed in the product. The mixture was then rotary evaporated to remove any dioxane residue. A white precipitate was formed. The white solid was then dissolved in water and acidified to pH 2 in an ice-bath by 4M hydrochloric acid. The product's pH was then tested with litmus paper. A white precipitate was produced as the pH decreased. The product was then vacuum filtered via Buchner filtration. The solid adduct was washed with water several times. The pH was tested once more to ensure the acidity of the product. The white solid was then oven dried at 85 oC overnight. A sample was then taken for proton NMR analysis to determine the product obtained. It was found that the product was indeed isophthalic acid. Once out of the oven, the product was refluxed in ethanol (50 cm3) at 50-60 oC for a period of three hours to separate sodium chloride salt from isophthalic acid as the isophthalic acid is soluble in ethanol and the sodium hydroxide is insoluble in ethanol. The white mixture transformed into a light pink creamy complex. Additional ethanol (10 cm3) was then transferred into the round-bottom flask (250cm3) and the mixture was left to reflux for further 25 minutes. The solution was then hot filtrated. It was then washed down with ambient temperature ethanol. The liquid product was then transferred into a round-bottom flask (250cm3) and was rotary evaporated to remove excess ethanol. The final product was then air-dried and weighed. 89.23 % yield was acquired. A sample was then taken for proton NMR (Bruker), Infrared spectroscopy (Nicolet 100IR) and mass spectral analysis. The adduct was confirmed as pure isophthalic acid. [27]

Scheme 7 (eMolecule)

Synthesis of Isophthalic acid from Isophthalonitrile. [27]

Synthesis of Furan-2,5-dicarboxylic acid

A mixture of 5-methyl-2-furonitrile (0.5 g, 4.67 mmol), 5M sodium hydroxide (6 cm3), and dioxane (3 cm3) was transferred into a round-bottom flask (250cm3) equipped with a magnetic follower. A reflux apparatus was then set up with the use of paraffin oil bath. The reflux was then stabilized at 90 oC and the mixture was allowed to reflux overnight. A yellowish mixture was formed. The apparatus was allowed to cool down to room temperature. The mixture was then rotary evaporated to remove the volatile dioxane. The precipitate obtained was then dissolved in water and was acidified to pH 2 in an ice-bath by 4M hydrochloric acid. The acid was then left in the ice-bath to cool to facilitate crystal formation. No crystals were observed. The sample was once again rotary evaporated. A yellow solid remained in the flask. A sample of the product was then sent for proton NMR and mass spectrometry and was found to be the intermediate 5-methyl-2-furancarboxylic acid. The yellow intermediate was then weighed and 86.7 % yield was obtained. The experiment was then terminated at the intermediate stage due to lack of laboratory time. [27]

Scheme 8 (eMolecule)

Synthesis of Furan-2,5-dicarboxylic acid from 5-methyl-2-furonitrile. [27]

Synthesis of 5-nitro-2-thiophene carboxylic acid

A mixture of 5-nitro-2-thiophene carbonitrile (0.3 g, 1.94 mmol), 5M sodium hydroxide (5 cm3), and water (3 cm3) was placed into a round-bottom flask (250cm3) equipped with a magnetic follower. A reflux apparatus was then set up with the use of a paraffin oil bath. The reflux was then stabilized at 90 oC and the mixture was allowed to reflux overnight. The mixture's color had changed from yellow to dark red after 30 minutes of refluxing. The mixture was then allowed to cool down to room temperature. It was then acidified in an ice-bath by 4M hydrochloric acid. Fumes formed in the round-bottom flask as the acid was being added. The color changed from dark red to dark brown as the pH dropped. The mixture was then left to crystallize in an ice-bath for a period of one hour. Dark brown pellets were formed. The product was then centrifuged for 10 minutes at 4,000 RPM (MSE Henderson Blomedical LTD) to separate the pellets from the liquid. The top liquid layer was discarded. The pellets were then left to air-dry. They were then weighed and 50.45 % yield was obtained. A sample was then taken for proton NMR and mass spectral analysis. The product was found to be 5-nitro-2-thiophene carboxylic acid. [27]

Scheme 9 (eMolecule)

Synthesis of 5-nitro-2-thiophene carboxylic acid from 5-nitro-2-thiophene carbonitrile.[27]

Synthesis of methyl pyrrole-2,5-dicarboxylic acid

A mixture of 1,5-dimethyl-2-pyrrole (0.5 g, 4.16 mmol), 5M sodium hydroxide (5 cm3), and water (3 cm3) was transferred into a round-bottom flask (250cm3) equipped with a magnetic follower. A reflux apparatus was then set up with the use of a paraffin oil bath. The reflux was then stabilized at 90 oC and the mixture was allowed to reflux overnight. The apparatus was allowed to cool down to room temperature. A clear solution was formed. The mixture was then acidified to pH 2 in an ice-bath by 4M hydrochloric acid. The clear solution turned into a white paste as the acid was being added. The paste was then vacuum filtered via Buchner filtration apparatus. The product was then oven dried at 80 oC overnight. The intermediate was then weighed and 70.34 % yield was obtained. A sample was taken for proton NMR and Mass spectrometry. Both techniques failed to produce results due to the samples high insolubility. An Infra-red spectrum was then obtained. It identified the product as the intermediate 1,5-dimethyl pyrrole-2-caboxylic acid. [27]

Scheme 10 (eMolecule)

Synthesis of methyl pyrrole-2,5-dicarboxylic acid from 1,5-dimethyl-2-pyrrole. [27]

Results

Product name

Product molecular formula

Product molecular mass (g/ mole)

Theoretical Weight (g)

Experimental Weight (g)

Percentage Yield (%)

Isophthalic acid

C8H6O4

166.13

0.650

0.580

89.23

5-methyl-2-furan carboxylic acid

C6H6O3

126.11

0.729

0.588

86.7

5-nitro-2-thiophene carboxylic acid

C5H3NO4S

173.14

0.337

0.170

50.45

1,5-dimethy pyrrole-2-carboxylic acid

C7H9NO2

139.15

0.704

0.580

70.34

Table 1

Information & Results of products synthesized.

Isophthalic Acid:

Figure 6 (eMolecule)

Structure of isophthalic acid with numbered hydrogen environments.

Proton NMR

: (1) 7.59 (1H) triplet, (2) (4) 8.24 (3H) doublet, (3) 8.65 (2H) singlet

Infrared spectrum

O-H group broad peak at 3240-2440 cm-1, C=O group peak at 1760-1640 cm-1, H-C=C group (aromatic) weak peak at 3150-3000 cm-1, C=C group (aromatic) peak at 1600-1450 cm-1.

Mass spectrum

M+ 165.88 m/z, M-1.51 (H) 164.37 m/z, M-15.95 (CH4) 149.93 m/z, M-17.05 (OH) 148.83 m/z, M-28 (CO) 137.88 m/z, M-45.29 (CO­2H) 120.59 m/z, M-89.95 (2CO­2H) 75.93 m/z, M-90.95 (2CO­2H, H) 76.93 m/z, M-100.97 (2CO­2H, C) 64.91 m/z, M-114.98 (2CO­2H, C2H2) 50.90 m/z.

5-methyl-2-furan carboxylic acid

Figure 7 (eMolecule)

Structure of 5-methyl-2-furan carboxylic acid with numbered hydrogen environments.

Proton NMR

: (1) 2.51 (3H) singlet, (2) 6.29 (1H) doublet, (3) 7.11 (1H) doublet, (4) 12 (1H) singlet.

5-nitro-2-thiophene carboxylic acid

Figure 8 (eMolecule)

Structure of 5-nitro-2-thiophene carboxylic acid with numbered hydrogen environments.

Figure 9 (eMolecule)

Molecular structure of CD3OD (Deuterated methanol) with numbered hydrogen environments.

Proton NMR

: (1a) 3.30 (3H) singlet, (2a) 4.90 (1H) singlet.

Mass spectrum

M+ 177.20 m/z, M-44.04 (CO2) 133.16 m/z, M-92.20 (CO2, NO2) 85.02 m/z, M+44.25 (CO2) 221.25 m/z, M+84.27 (2CO2) 261.27 m/z, M+128.27 (3CO2) 305.32 m/z, M+172.27 (4CO2) 349.37 m/z, M+216.27 (5CO2) 393.42 m/z, M+260 (6CO2) 437.47 m/z.

1,5-dimethyl pyrrole-2-carboxylic acid

Figure 10 (eMolecule)

Structure of 1,5-dimethyl pyrrole-2-carboxylic acid with numbered hydrogen environments.

Proton NMR

Not obtained

Mass Spectrum

Not obtained

Infrared spectrum

O-H group broad peak at 3240-2440 cm-1, -CH3 group peak at 3000-2800 cm-1, C=O group peak at 1760-1640 cm-1.

Conclusion & Discussion

The Suitable novel compounds synthesized were designed based on the structures of L-glutamate and 2-oxoglutarate so as to act as potential glutamate dehydrogenase inhibitors preventing the conversion of L-glutamate into 2-oxoglutarate in the Plasmodium Falciparum parasite.

The compounds were synthesized under alkaline conditions rather than acidic conditions due to the rapidity and undemanding nature of the reaction.

4M Hydrochloric acid was prepared by the addition of the acid onto the water. The addition of water onto a concentrated acid causes liberation of a large quantity of heat (exothermic reaction). Therefore, when water is added onto an acid; water turns into hot steam which then bursts out of the flask/container along with the scorching concentrated acid corroding the surface around it as well as causing severe burns and injuries to the chemist handling it.

Isophthalic acid was synthesized and obtained by the hydrolysis of the Isophthalonitrile's two cyano groups. The compound was analyzed via proton NMR which showed signals for all expected hydrogen environments; infrared which showed peaks of all accounted for functional groups as well as mass spectrometry (as explained in the results section). It was concluded that the product obtained was indeed isophthalic acid. However, a yield of 89.23 % was obtained. That might have been a result of numerous transfers of the chemical throughout the experimentation.

The synthesis of furan-2, 5-dicarboxylic acid from 5-methyl-2-furonitrile was not carried out. The experiment was stopped at the intermediate 5-methyl-2-furancarboxylic acid. Further oxidation had to be done to convert the methyl group into a carboxylic acid. The oxidation was meant to be preformed with the aid of water and KMnO4 (a strong oxidizing agent). [28] However, due to the lack of laboratory sessions the oxidation of methyl was not achieved. A yield of 86.7 % of the intermediate was obtained. The compound was analyzed via proton NMR showing signals at all appropriate hydrogen environments as well as infrared spectroscopy which indicated the accounted for functional groups. It was concluded that the product gained was indeed the intermediate 5-methyl furan-2-carboxylic acid.

5-nitro-2-thiophene carbonitrile was hydrolyzed under basic conditions to yield 5-nitro-2-thiophene carboxylic acid. A product was obtained from the experiment with a yield of 50.45%. However the identification of the chemical was not possible. A proton NMR was obtained showing only solvent deuterated methanol (cd3od) peaks. Mass spectrometric analysis was also carried out. The mass spectrum data showed a repeating gain of 44 units, which is consistent with the gain of a CO2 group. As a conclusion, the chemical was believed to have polymerized during the acidification of the carboxylate group into a carboxylic acid group. Further testing was required to prove the polymerization reaction, however due to the lack of laboratory time; the assumption could not be confirmed.

-H2

Where R = NO2, R'=CO2H

(-R & -R' bonds have been shortened for clarity).

Scheme 11 (eMolecule)

The polymerization reaction of thiophene. [6]

Methyl pyrrole-2,5-dicarboxylic acid was not acquired from pyrrole-2,5-dicarboxylic acid. The experiment was eliminated at the intermediate 1,5-dimethy pyrrole-2-carboxylic acid due to time shortage. Further oxidation had to be done to convert the 5-methyl group into a carboxylic acid. The oxidation was meant to be preformed with the aid of water and KMnO4 (a strong oxidizing agent). [28] A yield of 70.34 % of what was believed to be the intermediate was obtained. However the identity of the compound remained unknown. An attempt to analyze and authenticate the product took place but neither proton NMR nor a mass spectrum were obtained due to its high insolubility in organic solvents. The compound was believed to have polymerized during the acidification by 4M HCl of the 2-carboxylate group into a 2-carboxylic acid group. Further testing was necessary to confirm the polymerization reaction, however due to the lack of laboratory time; the assumption could not be definite.

-H2

Where R = CO2H

(-R & -CH3 bonds have been shortened for clarity).

Scheme 12 (eMolecule)

The polymerization reaction of pyrrole. [6] [29]

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