Chemistry: Carbon Compound (Alkanes,Alkenes,Carbox,Alcohol,Esther)

8/7/2019 Chemistry: Carbon Compound (Alkanes,Alkenes,Carbox,Alcohol,Esther)

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CHAPTER 2 : CARBON COMPOUNDS

- It can be divide into 2 groups : 1) organic 2) inorganic

- Organic compounds = carbon containing compounds (such as protein, alcohol etc)

- Inorganic compounds = non-carbon containing compounds (silica, marble, bauxite etc.)

HYDROCARBON

- Contain only carbon and hydrogen.

- 2 groups : a) saturated b) unsaturated

- Saturated = the molecules are made entirely ofcarbon-carbon single bond.

- Unsaturated = contain at least one carbon-carbon double or triple bond (multiple

bonds).

ALKANES

- Saturated hydrocarbons with general formula ofCnH2n + 2 , n = 1,2,3,..

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- How to name the alkanes ??

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- The naming is based on the IUPAC.

- The ending of the IUPAC name indicates the family of the compound.

- For this alkane group , the ending of the name is ane.

- Steps to name the alkane group ;

- a) determine the number of carbon atoms in the molecule

- b) select the correct root name ( meth-, eth-, prop-, but-, etc.)

- c) add the ending ane to the selected root name.

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Formula ;

- Steps to draw the structural formula ;

- 1) Position the carbons in a row

- 2) Join the carbon atoms by single bonds.

- 3) Place the other bond around the carbon atom. (not more than 4 bonds)

- 4) Attach hydrogen atom to each empty bond of a carbon atom.

- Physical Properties of Alkanes

- 1) Cannot conduct electricity

- 2) Low melting and boiling points.

- 3) Dissolve in organic solvent but insoluble in water.

- 4) Less dense than water.

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1)molecular formula (shows the actual number of atoms)

2) structural formula (shows the order in which atoms are bonded

together and by what types of bond.


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Chemical Properties of Alkane

1) Generally, alkanes are unreactive.

2) Combustion

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- with sufficient oxygen, complete combustion will form carbon dioxide

and water.

- if insufficient, the alkane will produce carbon monoxide and water first

and react again to form CO2 and H2O


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3) Halogenation

ALKENES

The general formula is CnH2n

Functional group = carbon-carbon double bond.

The functional group => determines the chemical properties of the organic molecule

The naming method is similar except the ending of alkene must be ene.

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- Reaction of alkanes with halogens.

- It is a substitution reaction (each hydrogen atom in the alkane molecule is

substituted by a halogen atom.


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a) identify the longest continuous carbon chain that contains the double bond.

b) count the number of carbon atoms in the chain.

c) number the carbon atoms in the longest chain and begin at the end near of the double

bond.

d) identify the location of the double bond by using the number of the 1st carbon atom in the

double bond.

e) place the number in front of the ending ene (for molecules with more than than 3 carbon

atoms).


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How to draw the structural formula of alkene???

Physical properties of alkenes :

Chemical Reactions of Alkenes

Alkenes are more reactive than alkanes.

1) Combustion (similar with alkane)

2) Addition Reactions

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1) position the carbon atoms in a row

2) join the first two carbon atoms with a double bond.

3) join the remaining carbon atoms with single bond

4) place the single bonds for the hydrogen atoms.

5) attach the hydrogen atoms to each empty bond of a carbon atom.

1) low melting and boiling point. ( the higher the number of carbon atoms,

the higher the value of melting and boiling point).

2) liquid and gaseous alkenes have lower densities than water.

3) dissolve in organic solvent but not in water.

4) cannot conduct electricity.

a) there are 2 types :

1) addition of hydrogen

2) addition of halogens

- e.g react with bromine solution

-

- so,bromine solution can be used as the reagent for testing the presence

of carbon-carbon double bond

3) addition of hydrogen halides (HBr, HF , HCl)

4) addition of water (hydration)

- will form alcohol

- the conditions are H3PO4 at 300oC and 60atm

5) addition of hydroxyl groups

- alkene is treated with a dilute acidified solution of potassium manganate

(vii). (decolourised)

- it will produce a colorless organic compound called diol

-dilute acidified solution of potassium manganate (vii)

be used as the

reagent to test for the presence of a carbon-carbon double bond.


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3) Polymerisation reaction

Small alkene molecules undergo an addition reaction with one another to form a long chain

called polymers.

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ISOMERISM

A phenomenon whereby 2 or more molecules are found to have the same molecular

formula

They are the same in terms of number and types of atoms but only differ in the

arrangement. (molecules which have different structures)

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In alkanes group (e.g)

In alkenes group (e.g)

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General steps of drawing isomers;

How to name the isomers????

- In isomers, there are branches-chain structures and they are called as alkyl group ( CnH2n+1 )

- For this alkyl group naming, just replace the ane for the name of corresponding alkane

with yl. (place at the early name of the molecule)

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1) Draw all the possible carbon skeletons.

2) For each carbon skeleton, place a double bond at different location (only for

alkene group!!!!)

3) Place single bonds around each carbon atom ( each carbon has 4 bonds)

4) Place hydrogen atoms.

1) Find the longest continuous carbon chain in the molecule.

2) Give the name for this longest chain.

3) Number the carbon atoms in this longest chain beginning at the end nearer to the

branches if alkane or nearer to double bond if alkenes ( number the carbon atoms twice,

left->right and right -> left)

4) Locate and name the attached alkyl groups.The position of each alkyl group is given

the number of the carbon atom to which it is attached on the chain.

5) Complete the name for the molecule by combining the three component parts

together. Write the name as the single word. (e.g 2,2-dimethylbutane, 2-methylpropane)

6) For alkene group, do not forget to mention the position of its functional group as well.(e.g 3-methylbut-1-ene )


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ALCOHOLS

- Non-hydrocarbons ( contains C, H, O )

- Functional group = hydroxyl group ( - O H ) (not hydroxide ion!!)

- General formula = CnH2n+1OH

- The naming of alcohols are quiet similar with the previous naming steps of isomer. Just

replace the end of the name with oland mention the location of the hydroxyl group.

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- Industrial production of alcohol ;

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- 1) Fermentation process

- 2) Hydration Process

Chemical Properties of Alcohol

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a) anaerobic process (it takes place in the absence of oxygen)

b)

c) temperature = 18 -20 o C

catalyst = zymase from yeast

other condition = absence of oxygen

- temperature = 300o C

- pressure = 60atm

- catalyst = phosphoric acid


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- 1) Combustion

- 2) Oxidation

- alcohols can be easily oxidized to carboxylic acid (-COOH)

- use the acidified potassium manganate (vii) ( it will be decolourised)

- 3) Dehydration

- alcohol turns back to alkene

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- removal of H2O molecule

- reagent = bromine water (decolourised) and potassium manganate (vii) (decolourised)

- in lab testing = 1) alcohol vapour is passed through the heated catalyst (porcelain)

2) ethanol is heated under reflux at 170o C with excess concentrated

sulphuric acid.

CARBOXYLIC ACIDS

- Containing elements ofC, H, O.

- General formula = CnH2n+1COOH

- Functional group = -COOH (carboxyl group)

- How to name carboxylic acid???

- Just replace the end of the corresponding chain of alkane with oic acid.

- e.g

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..

- Physical Properties for Ethanoic Acid

- How to make ethanoic acid???

- By using the process of oxidation of alcohol = (refluxing ethanol with an oxidizing agent

such as acidified potassium dichromate (vi) solution!!!

- Chemical Properties ethanoic acid?????

- ........................................................................................................

-

-

- .

-

- What is esterification????

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1) Colourless liquid at room temperature.

2) Sour smell like vinegar

3) Very soluble in water.


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- Carboxylic acid reacts with alcohol to produce a sweet-smelling compound called an

ester and water with condition of a few drops of concentrated sulphuric acid.

- Could you state the usage of carboxylic acids???

-

-

ESTERS

- Non-hydrocarbons organic compound which contains C, H, O.

- General formula = CnH2n+1COOCm H2m+1

- Functional group = -COO (carboxylate group)

- How to name esters????

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1) Identify and name the alcohol part of the ester.

2) Identify and name the acid part of the ester

3) Combine the two parts to obtain the name of the ester

*(the alcohol part is named 1st

followed by the acid part,the name of an ester consistsof two separate words)*


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Chemistry: Carbon Compound (Alkanes,Alkenes,Carbox,Alcohol,Esther)

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Transcript of Chemistry: Carbon Compound (Alkanes,Alkenes,Carbox,Alcohol,Esther)