prelim org chem lesson 2 Flashcards
the simplest alkyne
acetylene
the simplest alkyne
acetylene
In ethylene, the actual angles are close to
120°
The VSEPR model predicts bond angles of
120°
because of restricted rotation about a carbon-carbon double bond, an alkene with two different groups on each carbon of the double bond shows
cis-trans isomerism
Use the ending -ene to show the presence of the C=C
alkenes
use the ending -yne to show the presence of the triple bond.
alkynes
that contain more than one double bond are named as alkadienes, alkatrienes, and so on.
alkenes
Those that contain several double bonds are referred to more generally as
polyenes
polyenes (greek:
poly, many
are nonpolar compounds.
Alkenes and alkynes
are insoluble in water but soluble in one another and in nonpolar organic liquids.
Alkenes and alkynes
that are liquid or solid at room temperature have densities less than 1.0 g/mL; they float on water.
Alkenes and alkynes
a compound whose carbon skeleton can be divided into five-carbon units identical with the carbon skeleton of isoprene.
terpene
Most alkene addition reactions are
exothermic
Markovnikov’s rule
H adds to the less substituted carbon and X to the more substituted carbon.
when a reaction has two or more possible products, but one of the products is preferred over the other(s)
regioselective
Chemists account for the addition of HX to an alkene by a two-step
reaction mechanism
shows the origin of the electron pair (either on an atom or in the double bond).
tail of an arrow
shows its new position.
head of the arrow
head of the arroshow us which bonds break and which new ones form.
Curved arrows
Addition of water is called
hydration
is acid catalyzed, most commonly by H2SO4
hydration
the single most important reaction of alkenes is
polymerization
polymer:
monomer:
Greek: poly, many and meros, part
Greek: mono, single and meros, part
can be reproduced by repeating the enclosed structure in both directions.
structure of a polymer chain
a highly branched polymer; polymer chains do not pack well and London dispersion forces between them are weak.
Low-density polyethylene (LDPE)
softens and melts above 115°C.
Low-density polyethylene (LDPE)
approximately 65% used for the production of films for packaging and for trash bags.
Low-density polyethylene (LDPE)
only minimal chain branching; chains pack well and London dispersion forces between them are strong.
High-density polyethylene (HDPE)
has higher melting point than LDPE and is stronger
High-density polyethylene (HDPE):
can be blow molded to squeezable jugs and bottles.
High-density polyethylene (HDPE):
