Topic 1: Organic Compounds: Alkanes and Cycloalkanes According to Chemical Abstracts, there are more than 18 million known organic compounds, each of which has its own physical properties, such as melting point and boiling point,
Alkanes and Cycloalkanes
Taxol, isolated from the bark of the Pacific Yew tree, Taxusbrevifolia, is an anticancer drug, which was first studied in the successful treatment of ovarian cancer.
In 1969, 1,200 kg of tree bark was processed to produce
10.0 g of pure taxol. The molecule contains 14 functional groups.
Since it would be impractical to harvest enough trees to obtain significant amounts of taxol, a semi-synthetic method
Needles are harvested from a related, low growing evergreen, Taxusbaccata, which is grown in
plantations similar to growing tea.
The needles are processed to produce large amounts of a synthetic precursor
10- deacetylbaccatinwhose structure is shown below.
* You saw in Background Unit One that carbon-carbon single
bonds result from head-on overlap of carbon sp3 hybridized orbitals.
One of the unique properties of carbon is its ability to bond to multiple carbon atoms results in long chains of atoms and the formation of complex molecules.
* In earlier times when relatively few pure organic molecules
were known, new compounds were named at the whim of their
discoverer. Thus, urea (CH4N2O) is a crystalline substance isolated
from urine; morphine (C17H19NO3) is a painkiller named after
Morpheus, the Greek god of dreams; and barbituric acid is a tran-
quilizing agent named by its discoverer in honor of his friend
As the number of known organic compounds slowly grew, so did the
need for a systematic way of naming them. Although many “common” naming for organic compounds still exist, the system of naming we used is devised by the International Union of Pure and Applied Chemistry (IUPAC, usually spoken as “eye-you-pac).
What is the
Where are the
The names of alkanes are derived from a set of prefixes, used to
indicate the number of carbons present
YOU MUST KNOW THESE!
The names of alkanes end in -ANE
* Alkanes are sometimes referred to as “paraffins”- a word
derived from the Latin parumaffinis, meaning “slight
affinity.” This term aptly describes their behavior because
alkanes show little affinity for other some substances and are,
for the most part, chemically unreactive.
= stronger temporary dipoles
= more energy (higher temps.) needed to break the van der
The general class of compounds known as steroids contain four rings joined together- three of them six-membered rings and one of them a five membered ring.
Cortisol, also known as hydrocortisone,
an over the counter medicine used to
treat skin irritations.
Cholesterol is essential for all animal life.
Each cell synthesizes it from simpler
molecules, a complex 37-step process.
* In many ways, cycloalkanes behave similar to their open-
chain counterparts. One difference is that cycloalkanes are
less flexible. In smaller rings (C3 – C6), rotation about the
C – C bond is impossible. This leads to the ring having a
“top” and a “bottom” side.