Organic chemistry for GAMSAT

[simran]

Esterification, production of an ester from an alcohol and a carboxylic acid

[simran]

diene- compounds with two carbon to carbon double bonds

[simran]

decarbonylation- loss of CO

decarboxylation - loss of CO2

dehydration- loss of H2O, often leading to the formatio of a C=C double bond

dehydrogenation - loss of H, leading to an increase of unsaturated bonds. Eg from cycloheaxe to Benzene. Plantinum, charcoal, or selenium catalysts are needed.

dehydrohalogenation - loss of HX, where X= halogaen.Tends to leave a pi bond.

delocalisation - bonding electrons have to be considered as being delocalised over the whole group. Usually makes the group more stable. This extra stability is called the delocalisation enegy. In benzene the six pi bonds are delocalised over the six carbons.

[simran]

Hydrogenation - a specific methothed of reduced where either H2 is directly added to the molecule, or a compound such as ch3OH is used to add the hydrogen. Catalysts are usually used, and high pressures increase the reaction rate.

Hydrolysis- used to describe the conversio of an ester into an alcohol and carboxylic acid (saponification), the addition of water to a compound for example

RCN + H20 --------------> RCONH2
nitrile water amide

and the dislacement of a group or radical by hydroxyl eg

RCH2Cl + H20 ------------> RCH2OH + HCl

Above reations normally need an acid or base catalyst.

[Jake]

Keep up the good work hun

[simran]

thanks, was bored studying- so thought ill try out a different method!

it actually works!

if theres any mistakes let me know, coz im just finding out things from my books, abit tired and all.

[simran]

ok substituted benzene compounds.

Ortho, meta, and para.

If there is a group attached to a benzene ring, that carbon atom to which it is attached is called Carbon number 1. Carbon numbers 2 and five are ortho with regards to carbon 1. Carbon numbers 3 and 5 are meta with regards to carbon number 1. Carbon number 4 (opposite to carbon 1) is para.

Think of it as para= parallel
meta = middle.

Different groups have different effects where subtitutions occur on the benzene ring. Some groups are meta directing- they direct substitutions onto the meta carbons. Other groups are ortho-para directing, causing further sustitutions to occur only on ortho and para carbons.

If the group attached to the benzene ring has one or more double bonds, it will be meta directing.

Heres a brief list:

Meta Directing

NO2
COOH
CN
SO3H
CHO

Ortho-para directing

CH3
OCH3
Cl
OH
NH2

[simran]

Electronic Subtitutions, common example- with benzene rings.

These include halogenation, sulphonation, nitration

halogenation- in non aromatics- halogenation is the addition of halogens, HX, or halogen containing compounds across a double bond.
In aromatics, halogenation is the substitution of a halogen for a hydrogen.

Nitration -

HNO3 +2H2SO4 ---------------> NO2+ + H3O+ + 2HSO4-

Reacting nitric and sulphuric acid produces the nitryl ion- NO2+ , an electrophile that can take part in electrophilic substitution.


Sulphonation - First sulphur (VI) oxide (sulphur trioxide) needs to be formed from conc. Sulphuric acid

2H2SO4 ------> SO3 + H3O+ + HSO4-

the sulphur trioxide has positive charge, making it a electrophile.

[weegie neurosurgeon]

Simran for heavens sake lass take a break ur brain will melt. But hey if this helps u study then great. If u wanna do some study with me over msn give me a holla!! Take it easy, dont want u to end up going manic over organic chem. love char xxxxxxx

[simran]

but its cool, this way I get to study and post at the same time!