For 1-iodo-1-hexene (I-CH=CH-CH2CH2CH2CH3), I am seeing 2 double triplet for 2 proton in the alkene region ( I-CH= and =CH-CH2) in 1HNMR. I checked spectrum in Lit. as well, they also have same pattern.
As per my understanding CH2-CH= should have double triplet, but I-CH= should have only doublet.....
Can anybody please help me out here...any reference..or any suggestion would be helpful to figure out this splitting pattern.
Thank you
What are the J-coupling for the I-CH= proton? If it is in a range of 1-2 Hz, it might be just a long range coupling with CH2 (I-CH=CH-CH2).
Thanks Oleksandr, it could be. but J is around 5. Although =CH j is 17.2 and 2, which is good as the double bond is trans. But I- CH2 has around 5 j value.
Both your doublets of triplets should have the same large three-bond doublet-splitting (this is the J between the alkene protons, near 10 or 15 Hz, depending on whether cis or trans). Each doublet is further split into triplets: H-2 by ca. 6 Hz due to the 3J with the two H-3, and H-1 by ca. 1.5 Hz due to the 4J, also with the two H-3. Nothing special, really.
Best regards.
Hi Vandana. I think the key to solving mystery is just iodine. It is a rather bulky nucleus, and should affect even the hydrogen in the carbon-3 making them magnetically not equivalent, which may explain the triplets and the different coupling constants observed for hydrogen 1 and 2. I agree that there is a long coupling distance. I am attaching a simulation where you can observe what I am saying. Best regards.
- Badges
- Science topic
- Similar topics
- Filing