Alkenes and Alkynes Flashcards

Flashcards about the structure, nomenclature, properties, and use of alkenes and alkynes.

What are alkenes?

Unsaturated hydrocarbons containing one or more carbon-carbon double bonds (C=C).

What is the general formula for alkenes?

CnH2n

What is the suffix used in naming alkenes?

-ene

What is the rule for numbering carbon atoms in alkenes?

Numbering should be closer to the C=C double bond.

What are dienes and trienes?

Alkenes with two (diene) or three (triene) double bonds.

Give an example of naming branched-chain alkenes.

4,6-dimethyl-2-heptene (CH3CH=CHCH(CH3)CH2CH(CH3)CH3)

What is the IUPAC name for CH3CH=CHCHCH3 (with a CH3 branch on the 4th carbon)?

4-methyl-2-pentene

What is the IUPAC name for CH3CHCH2CH=CHCCH3 (with CH3 branches on the 2nd and 6th carbons and the 5th carbon)?

2,2,6-trimethyl-3-octene

What are the physical properties of alkenes?

Nonpolar, low melting point (m.p), low boiling point (B.p), insoluble in water, and exhibit London dispersion forces.

Why are alkenes more reactive than alkanes?

The presence of the C=C double bond makes them a good site for reactions.

Give an example of an alkene application.

Ethene (C2H4) is a hormone that ripens fruits and is used to make polyethene plastics.

What are alkynes?

Unsaturated hydrocarbons that contain one or more carbon-carbon triple bonds (C≡C).

What is the general formula for alkynes?

CnH2n-2

What is the suffix used in naming alkynes?

-yne

What is the rule for numbering carbon atoms in alkynes?

Numbering should be closer to the C≡C triple bond.

Give an example of naming alkynes.

2,5-dimethyl-3-hexyne (CH3CH(CH3)C≡CCH(CH3)CH3)

What are the physical properties of alkynes?

Nonpolar, low melting point (m.p), low boiling point (B.p), insoluble in water.

Why are alkynes more reactive?

They are unsaturated similar to alkenes.

Give an example of alkyne use.

C2H2 (ethyne) produce enough heat to Cut metal