Benzaldehyde forms 2 stereoisomeric oximes. How may their configurations be determined?
X-ray crystallography or nmr?
There are 3 xylenes. Their melting points are 13 degrees C, -24 degrees C, and -48 degrees C. Nitration of the isomer with the 13 degrees C mp results in only one mononitrated product. The isomer with mp=-23 degrees C gives 2 mononitrated products, and the isomer with mp -48 degree C gives 3 mononitrated products. Write the structure for each respective mp isomer and their nitrtion products.
To determine the configurations of stereoisomeric oximes formed by benzaldehyde, you can use various methods, such as X-ray crystallography or nuclear magnetic resonance (NMR). Here's how each method can be used:
1. X-ray crystallography: This technique involves growing single crystals of the compound and subjecting them to X-ray diffraction. By analyzing the diffraction pattern, the three-dimensional arrangement of atoms can be determined, including the configuration of stereoisomers.
2. NMR: Nuclear magnetic resonance allows the characterization of molecules based on their interactions with a magnetic field. By analyzing NMR spectra, such as proton (1H) or carbon-13 (13C) NMR, one can observe the chemical shifts and coupling patterns of specific atoms in the compound. By comparing the NMR data of different stereoisomers, their configurations can be determined.
Now, moving on to the question about the three xylenes and their nitration products:
Based on the given information, we can deduce the structures and nitration products of the xylenes as follows:
1. The isomer with the melting point (mp) of 13 degrees Celsius gives only one mononitrated product. This suggests that it has only one possible position for nitration. The structure of this isomer is known as ortho-xylene.
2. The isomer with mp = -24 degrees Celsius gives two mononitrated products, indicating that there are two possible positions for nitration. This isomer is called meta-xylene.
3. The isomer with mp = -48 degrees Celsius gives three mononitrated products, indicating that there are three different possible positions for nitration. This isomer is called para-xylene.
Based on this information, we can write the structures of each isomer and their respective nitration products as follows:
Ortho-xylene (mp = 13 degrees Celsius):
CH3
|
CH3-CH-C6H4-NO2
|
CH3
Meta-xylene (mp = -24 degrees Celsius):
CH3
|
CH3
|
CH3-CH-C6H4-NO2
Para-xylene (mp = -48 degrees Celsius):
CH3
|
CH3
|
CH3-CH-C6H4-NO2
|
CH3
Please note that the placement of the nitro group (-NO2) in the structures indicates the positions of nitration based on the number of mononitrated products obtained.