CHEM152L(7_01_09)

CHEM152L(7_01_09) - CHEM 152L Summer 2009 Dienes are compounds with two carbon carbon double bonds Conjugated double bonds alternating double

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
CHEM 152L Summer 2009 7/01/09 Dienes are compounds with two carbon – carbon double bonds. Conjugated double bonds, alternating double single double bond systems. Cumulenes/allenes – carbon participates in two carbon-carbon double bonds. Cumulated double bonds Dienes that are separated by two or more single bonds basically have the same properties as those of isolated (or simple alkenes). We will call these types of dienes “ordinary”. Structure and stability of dienes – if we look at conjugated dienes and isomers that have the same number of double bonds, but are “non conjugated” we see that the conjugated system is more stable. Two reasons for this additional stability – 1) the single bond in a conjugated system is made up of sp 2 – sp 2 overlap, so ultimately this a stronger bond than the sp 2 – sp 3 bond that we see in an ordinary alkene. The stronger bond gives more stability. 2) delocalization – the pi system is just not shared in the alkene unit, but it is shared over the entire pi system. This is the idea of delocalization. Bond length of the single bond is shorter than what would be expected in a normal alkane.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CHEM 152L Summer 2009 Conjugated dienes exist in two stable forms – transoid or s-trans conformation Cisoid or s-cis conformation. s-trans to s-cis is simply a rotation of the single bond away, and it turns out that the s-
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 05/13/2010 for the course CHEM 152L taught by Professor Baldwin during the Summer '09 term at Duke.

Page1 / 7

CHEM152L(7_01_09) - CHEM 152L Summer 2009 Dienes are compounds with two carbon carbon double bonds Conjugated double bonds alternating double

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online