Organic Chemistry Flashcards
what are hydrocarbons?
molecules composed mainly of carbon and hydrogen atoms.
how many bonds does carbon form?
4
tetrahedral arrangement
109.5 degrees apart from each other
homologous series
a group of compounds that have the same general formula or have a unique functional group.
what are the defining features of alkanes?
- single C-C bonds
- saturated because the backbone is completely surrounded by carbons
- CnH2n+1
9
non
10
dec
11
undec
12
dodec
properties of alkanes
- shorter have lower BP because of less intermolecular bonds, less energy is needed to overcome them
- at room temp: ethane, propane and butane are gases
- larger are liquids and some are solids
- insoluble in water
- soluble in organic solvents
- shorter are more volatile (evaporate easily), increasing flash point (easier to combust)
- larger alkanes are more viscous
viscosity
depends on the interaction between molecules. Increased length, means increased strength of dispersion forces and thus viscosity increases.
alkyl groups
refers to branching from the backbone
isomer
chemical substances that have the same chemical formula but different structural formulas
what effect does branching have on chemical properties?
increased branching, decreased surface area and hence a decrease in intermolecular bonding, so a decreased BP
what are the features of alkenes?
- double C-C bond
- unsaturated because carbon backbone is not completely surrounded
- CnH2n
is a double bond a functional group?
yes
naming alkenes
- determine longest chain
- number the carbons closest to double bond and give the bond a number
properties of alkenes
- smaller have lower bP
- ethene, propene and butene are gases at room temp
- larger are liquids or solids (more than 16C)
- insoluble in water
- soluble in organic solvents
- C-C double bond makes the, highly reactive
what reactions can alkanes participate in?
- combustion
- substitution
what is a substitution reaction?
an atom or a functional group is swapped by another atom or group of atoms
what products are them of a substitution reaction?
the new hydrocarbon and the atoms removed that form a small molecule
what can alkanes form in substitution reactions?
halogenated hydrocarbons, amines, alcohols
important consideration in substitution reactions?
only saw one hydrogen atom at a time for a new atom or group of atoms
if a reaction occurs between an alkane and an excess of a new atom (eg. Cl2), a series of substitution reactions can occur
halogens in halogenated hydrocarbons
- only need one electron and are thus highly reactive and electronegative
- hydrogen is swapped for one
naming a halogenated hydrocarbon
- longest chain
- identify location of functional group
- use numbers to show position
- functional groups with functional groups in alpha order
what are amines? how are they formed?
- amino functional groups that have a nitrogen attached to two hydrogen atoms
- polar due to hydrogen bond
- can be produced by a substitution reaction where a hydrocarbon reacts with ammonia (NH3)
primary amines
C atom attached to NH2 is attached to one other alkyl group
secondary amines
C atom attached to NH2 is attached to two other alkyl groups
tertiary amines
C atom attached to NH2 is attached to three other alkyl groups