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ACD/Labs Blog

Mikhail Elyashberg
Philip Williams and co-workers isolated a new cytotoxic peptide, Tasiamide B (molecular formula C50H74N8O12) containing the unusual amino acid-derived residue 4-amino-3-hydroxy-5-phenylpentanoic acid. The structure of the peptide was determined through a combination of 2D NMR experiments and HPLC analysis of degradation products. The experimental data was submitted to the Structure Elucidator Challenge to determine if the software could propose the same structure.

Mikhail Elyashberg
Robert Capon and co-workers identified two new nematocidal depsipeptides, identified as phoriospongins A (molecular formula C52H82N11O15Cl) and B. The structures of the phoriospongins were determined by detailed spectroscopic analysis and comparison with the previously reported sponge depsipeptide cyclolithistide A. The experimental data was submitted to the Structure Elucidator Challenge to determine if the software could propose the same structure.

Mikhail Elyashberg
Botryococcus braunii is a colonial green microalga that is known for producing various types of hydrocarbons and other types of oils. In a 1998 publication, Okada and co-workers isolated and identified two new carotenoids in their efforts to better understand the relationship between colony color and hydrocarbon production, one of which was α-botryoxanthin A (molecular formula C74H112O2).

Mikhail Elyashberg
For more than a decade, ACD/Structure Elucidator has been used by industry and academic experts to help solve some of the toughest structure problems. Using data from various analytical techniques (NMR, MS, UV, and IR) Structure Elucidator can propose chemical structures that are consistent with ALL available analytical data.

Arvin Moser
Functional groups such as allene (C=C=C) and cumulene (C=C=C=C) present an interesting challenge in an elucidation project, especially when an elucidator is not expecting them. The 13C chemical shifts for allene carbons are typically expected at 80, 200 and 100 ppm +/- ~20 ppm per shift. The confusion, or better described as bias, arises at...

Arvin Moser
There are many ways to teach the process of elucidating unknown structures. Offering a student a visual guide, such as seeing firsthand a spectral dataset, can enhance the learning process and better equip the student on future work. Presented below is a typical elucidation question from a university test. The numerical values have been extracted...

Arvin Moser
After a long and arduous attempt at an elucidation, it is quite common to be left with more than one candidate structure. In some cases collecting more data is not an option and an exhaustive database/literature search turns up nothing useful, the alternative approach is to synthesize the proposed candidates and then compare the spectral...

Arvin Moser
Structure elucidation is a skill learnt through years of practice. One of the best ways to learn is to learn by example. I feel that there is no better way to do this than mentoring through specific scenarios step-by-step. My intentions behind this blog are to offer a unique source for chemists who use a...

Arvin Moser
A previous blog described the Internet as a valuable tool in searching for previous work based on a molecular formula. In addition to searching the Internet “directly”, certain online sites can assist and facilitate the search process. Some of these sites are free while others have a fee. Be aware that the Internet is full...

Arvin Moser
Searching for unknowns across an internal library or database can serve as a major time saver. A more accessible database is the Internet. Many chemists and elucidators search the World Wide Web using a mass, a molecular formula or a fragment. Be aware that proprietary data sent over the Internet runs the risk of being...