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Chemspider links: 4-chlorobenzaldehyde ethanol methanol 4-chlorobenaldehyde ethanol hemiacetal 4-chlorobenaldehyde methanol hemiacetal

Researcher

Cuepil Choi

Objective

To determine if hemiacetal formation from 4-chlorobenzaldehyde and ethanol would increase with increased amounts of ethanol and if the formation of hemiacetals from methanol and 4-chlorobenzaldehyde had a higher 4-chlorobenzaldehyde to hemiacetal ratio than 4-chlorobenzaldehyde and ethanol.

Prodedure

2.8088 g of ethanol was added to 0.1111 g of 4-chlorobenzaldehyde in 1-dram non screwcap vial 1-E and 1.6640 g of methanol was added to 0.1205 g of 4-chlorobenzaldehyde 1-dram non screwcap vial 1-M. Both were mixed through trituration and then were pipetted into an inner NMR tube with deuterated water in an outer tube. HNMR spectra were taken within an hour in a 500 mHz machine.

Results

HNMR 1 - (4-chlorobenzaldehyde and ethanol) approximately 1 hr, 10:1 ratio between aldehyde to hemiacetal
HNMR 2 - (4-chlorobenzaldehyde and methanol) approximately 1 hr, 10:1 ratio between aldehyde to hemiacetal
HNMR 3 - (4-chlorobenzaldehyde and ethanol) approximately 3hrs, 4.3:1 ratio between aldehyde to hemiacetal
HNMR 4 - (4-chlorobenzaldehyde and methanol) approximately 3 hrs, 4.3:1 ratio between aldehyde to hemiacetal, acetal peaks are visible now
sheet 1 - sheet for methanol and 4-chlorobenzaldehyde reaction

Discussion

The results show that methanol may allow higher amounts of hemiacetals to be formed because of its mechanism in interacting with the benzaldehyde. It will be interesting to see test 4-chlorobenzaldehyde mixed with a 1:1 mixture of ethanol to methanol. If methanol does have an advantage of interacting with benzaldehyde, more of the methanol than ethanol will be consumed in producing hemiacetals. Also, the production of acetals may suggest that methanol and 4-chlorobenzaldehyde may react to completion without any catalysts.

Conclusion

The 4-chlorobenzaldehyde and ethanol showed that doubling the ethanol gave a negligible changes in ratio from CRSEXP001. The 4-chlorobenzaldehyde and methanol showed that the ratio was almost double of 4-chlorobenzaldehyde and ethanol with the same benzaldehyde to alcohol ratio as 4-chlorobenzaldehyde and ethanol. Integration of spectrum 1 and 3 shows that aldehyde to hemiacetal ratio with ethanol was 10:1 while methanol was close to 4:1. After approximately 3 hrs, methanol and 4-chlorobenaldehyde produced trace amounts of acetal (almost 17:1 ratio between aldehyde to acetal)

Log

2013-07-09

11:07 mass of 1-dram non screwcap vial 1-E 4.7043g
11:11 0.1111g of 4-chlorobenzaldehyde added to vial 1-E
11:13 2.8088g of ethanol was added to vial 1-E
11:16 the mixture of ethanol and 4-chlorobenzaldehyde was mixed using a pipette
11:16 mixture was put into NMR tube 1-E and capped
11:28 mass of 1-dram non screwcap vial 2-M was 4.6415g
11:32 0.1205g of 4-chlorobezaldehyde added to vial 2-M
11:32 1.6640g of methanol was added vial 2-M
11:33 the second mixture was mixed using a pipette
11:33 second mixture put into second NMR tube 2-M and capped
11:51 first NMR tube containing the ethanol 4-chlorobezaldehyde mixture was reprepared when stray crystals from the cap fell into the tube
12:21 HNMR spectrum 1 of 1-E at 25.8 C
12:30 HNMR spectrum 2 of 2-M at 26 C
14:51 HNMR spectrum 4 of 2-M at 26 C
15:03 HNMR spectrum 3 of 1-E at 26 C