General and Organic Chemistry - Lecture 11 - Alkenes and Alkynes

A hydrocarbon that contains one or more carbon-carbon double bonds. with a suffix -ene

A hydrocarbon that contains one or more carbon-carbon triple bonds. with suffix -yne

VSEPR model predicts bond angels of 120^o
In ehtylene, the actual angles are close to 120^o
In substituted alkenes, angles about each carbon of the double bong may be greater than 120^o because repulsion between goups

Because of restricted rotation about a carbon-carbon double bond, an alkene with two different groups on each carbon of the double bone shows cis-trans isomerism.

1. The parent name is that longest chain that contains the C=C
2. Number the chain from the end that gives the lower number of carbons to the C=C
3. Locate the C=C by the number of its first carbon
4. Use the ending -ene to show the presence of the C=C
5. Branched-chain alkenes are named in a manner similar to alkanes; substituated groups are located and named.

Http://legacy.jefferson.kctcs.edu/users/kaya.muller/che120/supplements/orgnomenclature/worksheets/alkane-ene-ynes/answers.html

1. Number the carbons of the ring double bond 1 and 2 in the direction that gives the lower number to the substituent encountered first.
2. Number and list substituents in alphabetical order

Alkenes and alkynes are nonpolar compounds
The only attractive force between their molecules are London dispersion forces.
Their physical properties are similar to those of alkanes with the same carbon skeletons.
Alkenes are alkynes are insoluble in water but soluble in one another and in nonpolar organic liquid
Alkenes and alkynes that are liquid or solid at room temperature have densities less than 1.0h / mL; they float on water

London dispersion forces

It is a nonpolar molecule and is insoluble in water and soluble in other nonpolar organic liquids.

Less than 1.0 g/mL
Will float on water

Most alkene reactions are exothermic - the products are more stable (lower in energy) than the reactants

Hydrochlorination
the double bond breaks and the H goes to the C with the most H's

Th addition of water
The H goes to the C with more H's and the OH goes to the other C