UNSATURATED HYDROCARBONS Flashcards
a hydrocarbon in which the carbon chain or ring contains at least one carbon-carbon double bond or carbon-carbon triple bond
UNSATURATED HYDROCARBONS
- An acyclic unsaturated hydrocarbon that contains one or more carbon-carbon double bonds
- Alkene functional group is thus a ____________ group.
- An older but still widely used name for alkenes is _______. The term means “oil-forming”
- The ________ ending means a double bond is present.
- C=C
- olefins
- ene
ALKENE
- _______________, where n is the number of carbon atoms present.
- Thus, alkenes with one double bond have two fewer hydrogen atoms than alkanes.
- The two simplest alkenes
o __________ (C2H4)
o __________ (C3H6) - When two double bonds are present, the compounds are often called _________; for three double bonds the designation _____ is used.
- CnH2n
- ethene and propene
- diene & -triene
PHYSICAL PROPERTIES OF ALKENES AND CYCLOALKENES
- ________ in water, soluble in ________ solvents, and lower density than water
- Melting point is ______ than that of the alkane with the same number of carbon atoms
- Alkenes with 2 to 4 carbon atoms are ______ at room temperature.
- Unsubstituted alkenes with 5 to 17 carbon atoms and one double bond are ______, and those with still more carbon atoms are ________.
- Insoluble; nonpolar solvents
- gases
- liquids; solids
CHEMICAL REACTIONS OF ALKENES
- Combustion
- Addition reaction
- hydrogenation reaction
- halogenation
- hydrohalogenation
- hydration
symmetrical addition rx: hydrogenation & halogenation
asymmetrical addition rx: hydrohalogenation & hydration
- The combustion products are carbon dioxide and water
- _________ are, however, too expensive to be used as fuel.
- Pure alkenes
COMBUSTION
A chemical reaction in which atoms or groups of atoms are added to each carbon atom of a carbon-carbon multiple bond in a hydrocarbon or hydrocarbon derivative.
addition reaction
- a hydrogen atom is added to each carbon atom of a double bond.
- This is accomplished by heating the ______ & ______ in the presence of a catalyst (usually Ni or Pt).
- alkene and H2
HYDROGENATION REACTION
- a halogen atom is added to each carbon atom of a double bond.
___________ & ___________ are the two halogenation processes most commonly encountered.
- NO catalyst is needed.
- Chlorination (Cl2) and bromination (Br2)
- HALOGENATION REACTION
- one carbon atom of a double bond receives a halogen atom and the other carbon atom receives a hydrogen atom.
- require NO catalyst
- For symmetrical alkenes, such as
_______, only one product results from hydrohalogenation.
- ethene
HYDROHALOGENATION REACTION
- one carbon atom of a double bond receives a hydrogen atom and the other carbon atom receives an -OH group.
- requires a small amount of ___________ as a catalyst
- For symmetrical alkenes, only one product results from this
- H2SO4 (sulfuric acid)
HYDRATION REACTION
common names of 2 simplest alkenes
ethylene and propylene
- An acyclic unsaturated hydrocarbon that contains a carbon-carbon triple bond.
- The functional group is ________ group.
- C triple bond C
ALKYNE
- _______________, where n is the number of carbon atoms present.
- Thus, the simplest member of this type of alkyne has the formula, ______, and the next member, with n=3, has the formula ________.
- CnH2n-2
- C2H2 and C3H4
ethyne and propyne
Alkynes are _______ in water but soluble in ___________, have densities less than that of water, and have boiling points that __________ with molecular mass.
- insoluble
- organic solvents
- increase