Organic Chemistry -Hydrocarbons Flashcards
What does the end of the name tell you?
the type of compound
What does the beginning of the name tell you?
how many carbons
Trivial Names
Name that is used casually
IUPAC names
rules for names - used formally
Hyrdrocarbons ending
ane
General formula for hydrocarbons
CnH2+2
Formula for methane
CH4
Formula for ethane
C2H6
Formula for propane
C3H8
Do alkanes contain double or triple bonds?
no only single bonds
Formula for butane
C4H10
Straight butane
n-butane
butane with ‘backbone’
iso-butane
ipuc name for iso-butane
2-methylpropane
Pentane
C5H12
Hexane
C6H14
What is organic chemistry?
The study of organic compounds
What are the general exceptions to the carbon organic rule?
CO, CO2, bicarbonate and carbonates as well as cyanide salts; generally regarded as inorganic compounds
Hydrocarbons
Contain H atoms and C atoms
The four classes of hydrocarbons
alkanes, alkenes, alkynes and aromatics
1 Carbon atom
Methane CH4
2 Carbon Atoms
Ethane (C2H6)
3 Carbon Atoms
Propane (C3H8)
4 Carbon Atoms
Butane (C4H10)
n-butane
CH3CH2CH2CH3
Isobutane
CH3CHCH3 | CH3
5 Carbon Atoms
Pentane C5H12
6 Carbon Atoms
Hexane C6H14
7Carbon Atoms
Heptane C7H16
8 Carbon Atoms
Octane C8H18
9 Carbon Atoms
nonane C9H20
10 Carbon Atoms
Decane C10H22
How many isomers of hexane are there?
4
Isopentane

Neopentane
C | C-C-C | C
Alkyl Group
An alkyl group is an alkane without one of its H atoms
What is the alkyl group version of Methane?
CH3- (Methyl)
What is the alkyl group version of Ethane?
CH3-CH2- (Ethyl)
When should you not give the number in the name?
If the name without a number is unambiguous e.g Methylbutane
How reactive are alkanes, generally? and subsequent use in food?
Generally quite unreactive (simple akanes) - except their ready flammability - Subsequently used in foods such as coating dried fruit to stop sticking together - due to non reactivity.
Unders special conditions, hydrogen atoms in alkanes can be replaced with which groups? (6)
- Fluoro
- chloro
- bromo
- iodo
- cyano
- nitro
What are alkanes generally used as?
fuels (especially those with low molecular weights)
What are the lowest weight alkanes important parts of ?
natural gas
Alkanes with carbon numbers 6 - 12 are important parts of ?
petrol
Alkanes with carbon numbers 12 + are important parts of
diesel and fuel oils
How does an alkene differ from an alkane?
it contains a double bond between adjacent carbon atoms
How many bonds do alkynes have between adjacent carbon atoms?
three (triple bonds)
General formula for alkenes
CnH2n
Gen. formla for alkynes
CnH2n-2
Why are akenes and alkynes called unsaturated compounds?
Because they do not contain the maximum number of H atoms
When to use trans or cis in alkenes?
trans when the functional groups are on opposite sides such as trans but-2-ene
Or cis when the functional groups are on the same side of the double bond such as cis but-2-ene
How to name alkenes and alkynes?
Select the longest chain containing a multiple bond 2) alter name from ane to ene or yne 3), specify the position of the multiple bond (comes after functional group number) 4) when relevant - cis or trans
Important common alkenes and structures
Ethylene (used to ripen bananas) CH2=CH2
Propylene CH2= CHCH3
Addition reactions in alkenes?
Can occur accross the double bond to convert into a single bond (such as hydrogenation - increases melting point of oils)
2 examples of addition reactions which convert into single bonds?
RCH=CH2 + H2O –> RCH(OH)CH3
CH2=CH2 + HCl (g) –> CH2Cl-CH3
Iodine addition double bond conversion reaction in prac 3
RCH=CHR +ICl -> RCH-CHR
| | I Cl
Low molecular alkynes are extremely?
Flammable e.g ethyne used for cutting steel
Uses of alkenes and alkynes
in production of polymers - polyunsaturated fatty acids are essential trace components in diet
Aromatics
hydrocarbon with alternating double and single bonds between carbon atoms forming rings.
Benzene ring structure (expanded and condensed)
Expanded
condensed

toluene structure

Ortho
two groups come off two adjacent carbons
Meta
Two groups come off adjacent carbons with one separating them
Para
Two groups come off two carbons with another two carbons separating them
Name the five major benzene reactions
Nitration, Sulphonation, Halogenation, Alkylation, Acylation
Nitration reaction reagents and products formed
Reagents: HNO3 or H2SO4
Product

Sulphonation Reaction agent and product formed
H2SO4

Halogenation reagents and product formed
X2 (X =Cl or Br)
Catalysts: FeX3 or AlX3

Use of toluene
Starting material for production of saccarin, TNT, benzene and phenol
Aniline, structure and use
Use
- Production of dyestuff
- rubber antioxidants
- resins
- sulfonamide drugs

Phenol structure and use
Use:
- Phenolic resins from phenol and formaldehyde
- phenol and derivatives used widely as antiseptics e.g dettol

Cresol structure and use
Use
- Phenolic resins
- preparation of plasticiser for PVC and flame retardants
- weed killer

Xylenes structure and use
Use
- Polymer protection
- vitamin B2
- Pesticide production
