Question

How to interpret the C NMR of the complex 2-{[Dodecylsulfanyl) carbonothiolyl]sulfany) propanoic acid

C NMR SLT 0100 20.0 220.0 210.0 200.0 190.0 130.0 170.0 160.0 150.0 140.0 130.0 120.0 110.0 1000 90.0 800 70.0 600 500 400 300 20.0 10.0 XSparts per Mallion: Carbon13 C NMR 220.0 210.0 200.0 190.0 1800 1700 160.0 150.0 140.0 130.0 120.0 110.0 100.0 90.0 s0.0 700 60.0 500 40.0 30.0 20.0 10.0 0 -100 -20.0 xSparts per Million: Carbon13

Answer 1

As should be obvious there are only two carbons which can be responsible for the downfield signals. They are marked:

он 2-l (Dodecylsulfanyl)carbonothioyl]sulfanyl)propanoic acid

It is typically known that the carboxylic acid carbon has chemical shifts of around 170-180 ppm. This makes it clear that the red carbon would have 176.911 as its shift. The signal at 222.007 must then be attributed to the red carbon, which is intuitively obvious because this is like the sulfur analogue of a ketone, except that you have two more sulfur atoms on either side, making the carbon even more electron rich.

In the aliphatic region, it is difficult to assign each of the carbons separate ppm values. But, the terminal methyl and the branched methyl (1 and 2) respectively are attributed to the most upfield carbons. The carbon marked 3 is at 47.5 due to more deshielding. Same reason is valid for carbon 4 (37.5). The intermediate ppm values are due to the intermediate carbons.

он