slide1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Topic 1: Organic Compounds: Alkanes and Cycloalkanes PowerPoint Presentation
Download Presentation
Topic 1: Organic Compounds: Alkanes and Cycloalkanes

Loading in 2 Seconds...

play fullscreen
1 / 25

Topic 1: Organic Compounds: Alkanes and Cycloalkanes - PowerPoint PPT Presentation


  • 154 Views
  • Uploaded on

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,

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Topic 1: Organic Compounds: Alkanes and Cycloalkanes' - elsu


Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

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,
  • as well as its own reactivity.
  • Chemists have learned that organic compounds can be classified into
  • families according to their structural features and that members of a
  • given family often have similar chemical behavior.
  • Instead of 18 million compounds with random reactivity, there are a
  • few dozen families of organic compounds whose chemistry is
  • reasonably predictable.
  • Throughout this course, we will study the chemistry of specific families.
slide2

Functional Groups

  • FUNCTIONAL GROUP:
  • Group of atoms within a molecule that has a characteristic
  • chemical behavior
  • - Behaves nearly the same way in every molecule
slide5

Prozac

Caffeine

Acetominophen

Vanillin

slide6

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.

Taxol

slide7

Since it would be impractical to harvest enough trees to obtain significant amounts of taxol, a semi-synthetic method

was developed.

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.

  • 10- deacetylbaccatin
  • Synthetic precursor to taxol
  • More readily available
slide8

II. Alkanes and Alkane Isomers

* 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.

slide9

ALKANES:

  • contain single carbon to carbon bonds
  • hydrocarbons: contain only C & H atoms
  • saturated: contain the max. number of H atoms per C atom
  • have the general formula: CnH2n+2 (n = any integer)
  • nonpolar
  • STRAIGHT-CHAIN or NORMAL ALKANES:
  • carbons atoms are connected in a row
  • Ex.
  • BRANCHED-CHAIN ALKANES:
  • carbons atoms branch from the main chain
  • Ex.
slide10

CONSTITUTIONAL ISOMERS:

  • contain the same number & types of atoms but differ in the
  • way the atoms are arranged
  • - have different chemical and physical properties

Isomer Possibilities:

slide11

* Also remember that carbon- carbon single bonds can rotate.

  • What may at first seem like two different molecules may
  • really just be the same molecule represented in two different
  • ways.
slide12

III. Naming Alkanes

* 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

Barbara.

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).

slide13

A chemical name in the IUPAC system has three parts:

prefix parentsuffix

How many

carbons?

What is the

main functional

group present?

Where are the

substituents?

slide14

Naming Alkanes

The names of alkanes are derived from a set of prefixes, used to

indicate the number of carbons present

YOU MUST KNOW THESE!

meth-

hex-

eth-

hept-

prop-

oct-

but-

non-

pent-

dec-

The names of alkanes end in -ANE

slide16

IV. Properties and Reactions of Alkanes

* 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.

slide17

PROPERTY 1: ALKANES SHOW REGULAR INCREASES IN

  • BOILING & MELTING POINTS AS THEIR
  • MOLECULAR WEIGHT INCREASES
  • Due to van der Waals forces: weak intermolecular forces that
  • operate over small distances & occur because the electron
  • distribution in the molecules are non-uniform at any given
  • instant & create temporary dipoles

Bigger molecules

= stronger temporary dipoles

= more energy (higher temps.) needed to break the van der

Waals forces

slide18

PROPERTY 2: INCREASED BRANCHING LOWERS AN

  • ALKANES BOILING POINT
  • Branched-chain alkanes are more spherical, have smaller
  • surface areas, and therefore have weaker van der Waals
  • forces
  • - Weaker van der Waals forces = lower boiling point
slide19

REACTION 1: COMBUSTION

  • When hydrocarbons burn in the presence of O2, the products
  • are H2O and CO2
  • A lot of heat is produced
  • Ex. CH4 + O2 CO2 + H2O
slide20

REACTION 2: RADICAL HALOGENATION

  • Mixture of alkane and X2 is irradiated w/ ultraviolet light
  • (denoted as hυ) forming the X• radical (odd electron species)
  • Products contain a variety of halogen substituted products
  • Cons of reaction: difficult to control the exact spot of halogenation (see example below) & mixtures of products form
slide21

V. Cycloalkanes

  • CYCLOALKANES:
  • also called cyclic compounds
  • consist of rings of – CH2 – units
  • have the general formula: CnH2n

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.

slide22

VI. Cis-Trans Isomerism in Cycloalkanes

* 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.

slide23

STEREOISOMERS:

  • atoms are connected in the same order but differ in their
  • spatial orientation
  • CIS –TRANS ISOMERS:
  • a special type of stereoisomers
  • cis: means groups are on the same side
  • trans: means groups are on the opposite side
slide24

1,4- dimethylcyclohexane

1-methyl-3-propylcyclopentane

3-cyclobutylpentane

1-bromo-4-ethylcyclodecane

1-chloro-3-ethyl-2-methylcyclopentane

1-bromo-3-ethyl-5-propylcyclohexane

1-fluoro-2-methylcyclobutane

1-ethyl-4-methylcycloheptane

1,1,4-trimethylcyclohexane

3-cyclopentylheptane

1,3-dimethylcyclopentane

1-ethyl-2,2,6,6-tetramethylcyclohexane

slide25

3-ethyl-4-methylhexane

4-ethyl-5,6-dimethyl-7-propyldecane

3,4,5-triethyl-6-methyloctane

3,4-diethyl-2-methylhexane

1,2-diethyl-3-methylcyclohexane

1,4-dibromo-2-fluorocyclopentane

1-cyclopropyl-2-propylcyclopentane

2-cyclopentyl-6-methyloctane

5-ethyl-3-methyl-6-propylnonane