Friday 18 May 2012

Carbocylic acid and Ethers

Carboxylic Acids are formed by the functional group:



-this is also the simplest Carboxylic Acids called Methanoic acid
-use standard rules but change the parent chain ending to "-oic acid"


ETHERS

-an Ether contains an oxygen group connected to 2 alkyl (carbon) chains



-name the smaller alkyl group first, then the second alkyl group followed by "ether"




Alicyclics and aromatics


We learned about alicyclics and aromatics

Carbon chains can form 2 types of closed loops
Alicyclics are loops usually made with single bonds
If the parent chain is a loop standard naming rules apply with one addition: "cyclo" is added in front of the parent chain
There are 3 different ways to draw organic compounds:

  • Complete structural diagram
  • Condensed structural diagram
  • Line Diagram

Numbering can start anywhere and go clockwise or counterclockwise on the loop but side chain numbers MUST be the lowest possible!


CONDENSED STRUCTURAL DIAGRAMS

A condensed structural diagram always shows carbons and hydrogens in it
loops can also be side chains
same rules apply but the side chain is given a cyclo- prefix




NAMING COMPOUNDS


You see 2 lines connecting CH2 and C, so you know this organic compound forms a double bond and you must use the ending -ene
You count the longest carbon chain to be 5 so we use -pent
-pent + -ene = pentene and this bond occurs at 1 so: 1 pentene
we see a loop on #3 of the carbon chain so we must use to prefix -CYCLO and there are 3 of the CH's on it so we use propyl and carbon and hydrogen on #2
#2: 2 methyl
#3: 3 cyclopropyl
2 methyl 3 cyclopropyl 1 pentene


AROMATICS:

Benzene (C6H6) is a cyclic hydrocarbon with unique bonds between the carbon atoms
Structurally it can be drawn with alternating double bonds
Careful analysis shows that all 6 C-C bonds are identical and really represent 1.5 bond
This is due to electron resonance for electrons are free to move all around the ring


AROMATIC NOMENCLATURE:

A benzene molecule is given a special diagram to show its unique bond structure


A benzene can be a parent chain or a side chain
As a side chain it is given the name phenyl

Draw line diagrams
a) 1, 4 diethyl 2 methyl Benzene
b) 1,3,5 triethyl 2,4,6 tripropyl benzene





Organic Chem + Alkanes

Organic Chemistry is the study of CARBON COMPOUNDS
- Carbon forms multiple covalent bonds


Carbon Compounds can form chains, rings or branches
- There are less than 100,000 non-organic compounds
- Organic compounds number more than 17,000,000

The simplest organic compounds are made of carbon and hydrogen


CH4 (Methane)



CH3CH3 (Ethane)


- Saturated compounds have no double or triple bonds
- Compounds with only single bonds are called Alkanes and always end in "-ane"




NOMENCLATURE


There are 3 categories of organic compounds
1) Straight chains
2) Cyclic chains
3) Aromatics



STRAIGHT CHAINS


Rules for naming straight chain compounds:
1) Circle the longest continuous chain and name the base chain
- meth, eth, prop, etc.
2) Number the base chin so side chains have the lowest possible numbers
3) Name each side chain using the "-yl" ending
4) Give each side chain the appropriate number
5) List side chains alphabetically


Name the Alkanes!! :



Ketones and Aldehydes

KETONES & ALDEHYDES

A ketone is a hydrocarbon chain with a double bonded oxygen that is NOT on either end
An Aldehyde is a compound that has a double bonded oxygen at the END of the a chain.
Follow standard rules and add -one to the parent chain for Ketones
Follow standard rules and change the parent name ending to -al in Aldehydes

Propanone is a ketone. Propanal is an aldehyde. Their endings and where the oxygens are bonded

Here are some examples:

Draw the structural diagrams for the following Ketones:


a) 2, 4 dimethyl 3 pentanone
b) 2 chloro 4 methyl 3 hexanone
c) 1,2,2 trichloro 4,4 difloro 3 butanone





Name the following compound:



2 ethyl 4 floro 2 methyl 3 hexanone


ALDEHYDES


An aldehyde is a compound that has a double bonded oxygen at the END of a chain So Oxygen atoms will be found on the ends of these chains, and will have an ending of -al


Name the compound:








1) Count 4 carbons = Butane
2) Add ending "-al" to Butane = Butanal


Answer: Butanal

The simplest aldehyde is methanal otherwise known as FORMALDEHYDE:







Draw a structural diagram for
2,3 dibromo 4 propyl pentanal


Alkynes and Alkenes

In Chem class, we learned about double & triple bonds, trans & cis butene

Carbon can form double & triple bonds with carbon atoms
When multiple bonds form, fewer hydrogens are attached to the carbon atom
Naming rules are almost the same as Alkanes (single bonds) but instead we use 2 different endings
For DOUBLE BONDS (Alkenes) it ends with -ene (i.e Butene)
For TRIPLE BONDS (Alkynes) it ends with -yne (i.e Heptyne)
*The position of the double/triple bonds always has the lowest number and is put infront of the parent chain

Double Bonds -ene



1. First determine the longest carbon chain. The longest Carbon chain here is 6, therefore we use the stem name -HEX


2. Next, you see a double bond represented by 2 lines (circled in red). Then you know our ending has to end with -ene. So it is 1 Hexene


3. Since you've found your parent chain (1 Hexene), determine the side chains. On #3 and #4 you see a 2 carbon group therefore it is 3,4 diethyl


4. So your answer is 3,4 diethyl hexene


Triple Bond: -yne

MULTIPLE DOUBLE BONDS:

More than 1 double bond can exist in a molecule
Use the same multipliers inside the parent chain



TRANS & CIS BUTENE

If 2 adjacent carbons are bonded by a DOUBLE BOND and have side chains on them 2 possible compounds are possible
CIS and TRANS:








Can you name this compound?









Answer: 4 ethyl, 4,5 dimethyl1 heptene

Functional Groups

Functional groups are organic compounds that can contain elements other than Carbon or Hydrogen. These organic compounds contain elements such as Oxygen (alcohols), group 7 elements (halides), double bonded oxygens (ketones/aldehydes), a combination of a double bonded oxygen and an OH group (carboxylic acids) and Nitrogens (Amines)

ALCOHOLS
HALIDES

We will learn about nine functional groups!!!

Alcohols
Halides
Aldehydes
Ketones
Carboxylic Acids
Ethers
Amines
Amides
Esters

ALCOHOLS:

An alcohol is a hydrocarbon with a -OH bonded
Its ending is -OL (i.e Methanol)
Same naming rules apply
If a compound has more than one -OH group number both and add -diol, -triol, -tetraol, etc
Examples:




After observing the structural diagram try to find some clues to start. From this diagram you see there is an OH, therefore you know this is an alcohol and has to end with -OL
Count the longest carbon chain. The longest carbon chain is 8. Therefore, it is 1 Octanol
Name the side chains from 1 Octanol. 3 ethyl, 4 propyl
The compound is 3 ethyl, 4 propyl 1 octanol
Name the following Alcohols:




On the left: You see 2 OH groups and a carbon chain of 2 (eth-). Since this is an alcohol with 2 OH groups, we name this Ethanediol
On the right: We know that this is a benzene molecule. But it is not exactly a benzene molecule because it has an OH group attached to it. This is called a Phenol.


HALIDES:



Group 7 elements (F, Cl, Br, I) can bond to a hydrocarbon chain
Naming follows standard rules with halides using
floro-, chloro-, bromo-, and iodo-





Left: a carbon chain of 2. (Ethane). The name of this compound is: 1,1,2,2 tetrabromo ethane
On the right: You see a carbon chain of 3, and one is double bonded (prop, -ene). The name of this compound is: 2,3 dibromo 3 chloro 1 Propene

 Name the following compounds:





Answers:
(left) 1,3 dibromo 2,4 dichloro cyclobutane
(middle) 2 bromo, 1 ethyl, 3 floro benzene
(right) 3,3 diphenyl 1 propanol

Tuesday 10 April 2012

Intermolecular Bonds:

Types of Bonds:

1. Intramolecular bonds = within a molecule (*think intramural)
    - Ionic + Covalent

2. Intermolecular bonds = between molecules (*think international)
    - The stronger the intermolecular bonds the higher the BP or MP
    - 2 Types: Vander Waals bonds & Hydrogen bonds

Vander Waals Bonds:

  • Based on electron distribution
  • 2 Categories: 
  1. Dipole - Dipole bonds 
  • if a molec. is Polar, the + end of one molec will be attracted to the - end of another molec. 

     2.  London Dispersion Forces (LDF)
  • present in all molecs
  • creates the weakest bonds 
  • if a substance is non-polar Dipole - Dipole forces don't exist 
  • electrons are free to move around & will randomly be grouped on one side of the molec. 
  • Creates a temporary dipole and can cause a weak bond to form
  • the more e- in the molec. the stronger the LDF will be
EX//

- NH3 (10e) VS. C2H8 (18e)
  polar                  non-polar

- NH3 has the stronger bond because of it's Dipole-Dipole bond.  C2H8 is non-polar thus it's bond is LDF making it's bond weaker than NH3.

Hydrogen Bonding:

  • if hydrogen bonded to certain elements (F, O, & N) the bond is highly polar 
  • this forms a very strong intermolecular bond.  
EX//

- H2O (10e) VS. CH4 (10e)
  Polar                 Polar

- They are both Polar and both have the same amount of e- but H2O wins for the highest boiling point due to its Hydrogen bond.

A very helpful Video... :)