How are alkenes named?

1 Answer
Jul 23, 2018

Answer:

Well, what is standard operating procedure....

Explanation:

For a given olefin, as normal we identify the LONGEST carbon chain:

#H_3stackrel(1)C-CH=CH-stackrel(4)CH_3#

...the numbering is unambiguous here, and so we gots #"2-butylene"#...but for …

#H_3stackrel(1)C-CH=CH-stackrel(4)CH_2CH_3#...we choose to number such that the functional group has the LEAST number...and so the former is #"2-pentylene"#.

But of course both rings and olefinic bonds, sites of unsaturation, introduce another level of complexity...I could have...

wikipedia.org

...or....

wikipedia.org

Because the geometry is different while the carbon-carbon connectivity is the same, these are geometric isomers, that have different chemical and physical properties...