The goal of this puzzle is to resolve the ambiguity exhibited within a 2D NMR spectrum and thus provide the correct signal correlation.
The following 1H-13C HSQC-DEPT NMR spectrum shows two one-bond correlations linked to the 1H signals 2.75 and 3.50 ppm and two closely spaced 13C signals at 61.5 and 62.2 ppm. Does the 1H signal at 2.75 ppm correlate to the 13C signal at 61.5 ppm or the one at 62.2 ppm?
Note: the blue line was added to help align the correlation to the F1 domain.
The goal of this puzzle is to resolve the ambiguity exhibited within a 2D NMR spectrum and thus provide the correct signal correlation.
The following 1H-13C HSQC-DEPT NMR spectrum shows two one-bond correlations linked to the 1H signals 2.75 and 3.50 ppm and two closely spaced 13C signals at 61.5 and 62.2 ppm. Does the 1H signal at 2.75 ppm correlate to the 13C signal at 61.5 ppm or the one at 62.2 ppm?
Note: the blue line was added to help align the correlation to the F1 domain.
The goal of this puzzle is to determine how the molecular formulae of the intermediates may assist in reasoning out the final product.
In this puzzle, let’s consider the following one-pot synthetic reaction (solvents and additional reactants are not shown). The molecular formula (MF) and the RDBE information are also presented. The chemical reaction illustrates a C11 compound reacting to form a C9 compound and subsequently a C15 compound. The reaction continues and produces an unknown compound with a MF of C24 H23 N1 O2. Based on the given information, how can the MF of the unknown compound be explained?
The unknown comprises of 24 carbon atoms and so if you add the carbons from the 2nd intermediate with the carbons from the 3rd intermediate you arrive at the 24 carbons (9+15=24). This is also evident for the nitrogen atom count (0+1=1) and the RDBE count (5+9=14). This is not the case for the hydrogen (10+15=25) and oxygen (2+1=3) atoms. However, if the loss of a H2O molecule is considered, the unknown can be a combination of the 2nd and 3rd intermediate.
The goal of this puzzle is to determine how the molecular formulae of the intermediates may assist in reasoning out the final product.
In this puzzle, let’s consider the following one-pot synthetic reaction (solvents and additional reactants are not shown). The molecular formula (MF) and the RDBE information are also presented. The chemical reaction illustrates a C11 compound reacting to form a C9 compound and subsequently a C15 compound. The reaction continues and produces an unknown compound with a MF of C24 H23 N1 O2. Based on the given information, how can the MF of the unknown compound be explained?
The unknown comprises of 24 carbon atoms and so if you add the carbons from the 2nd intermediate with the carbons from the 3rd intermediate you arrive at the 24 carbons (9+15=24). This is also evident for the nitrogen atom count (0+1=1) and the RDBE count (5+9=14). This is not the case for the hydrogen (10+15=25) and oxygen (2+1=3) atoms. However, if the loss of a H2O molecule is considered, the unknown can be a combination of the 2nd and 3rd intermediate.
With the warm weather and some good football/soccer matches upon us, the blog P2C2E will be on hiatus for 2 weeks from June 7 to 18. Posts will resume the following week.
Stay tuned for more logic puzzles.
With the warm weather and some good football/soccer matches upon us, the blog P2C2E will be on hiatus for 2 weeks from June 7 to 18. Posts will resume the following week.
Stay tuned for more logic puzzles.
The goal of this puzzle is to logically combine a set of fragments using valence and NMR information.
In this puzzle, three fragments are correlated through 2-3J coupling responses (represented by a green arrow) that were extracted from a 1H-13C HMBC data (spectrum not shown). The carbon atoms with the 13C chemical shifts displayed in blue indicate the presence of an adjacent heteroatom. Based on these criteria, what 'complete' fragment(s) supports the data and is there anything missing?
In order to accommodate these restrictions, a logical fit is to consider a trivalent atom, e.g. nitrogen.
The goal of this puzzle is to logically combine a set of fragments using valence and NMR information.
In this puzzle, three fragments are correlated through 2-3J coupling responses (represented by a green arrow) that were extracted from a 1H-13C HMBC data (spectrum not shown). The carbon atoms with the 13C chemical shifts displayed in blue indicate the presence of an adjacent heteroatom. Based on these criteria, what 'complete' fragment(s) supports the data and is there anything missing?
In order to accommodate these restrictions, a logical fit is to consider a trivalent atom, e.g. nitrogen.
