core organics

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basic naming and definitions

• {{Functional group{{

The part of the organic molecule responsible for its chemical reactions.

• {{Homologous series{{

A series of organic compounds with the same functional group but with each successive member differing by CH2

• @@Aliphatic hydrocarbons@@:

  In which carbons are joined together in either straight or branched chains, or non aromatic rings.

• @@Alicyclic hydrocarbons@@:

  In which the carbon atoms are joined together in a ring structure but are not aromatic.

• @@Aromatic hydrocarbons@@:

In which there is at least one benzene ring in the structure.

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• Naming

  prefix= additions to the main chain and where

  stem= length of the longest carbon chain

  suffix= major functional group

  -prefixes are arranged in alphabetical order eg 1-ethyl 2-methyl

  -the numbers are from the C that the extra group comes off (in order of the longest C chain)

Functional groups:

• $<strong>alkene</strong>$= contains carbon carbon double bonds
• $<strong>alkane</strong>$= just c and h
• $<strong>haloalkane</strong>$= -cl,br,i/ (chloro, bromo, iodo-)
• $<strong>alcohol</strong>$= bond must be to the oxygen (-ol)
• $<strong>aldehyde</strong>$= -cho/ c=o (-al)
• $<strong>ketone</strong>$= -coc/ double bonded (-one)
• $<strong>carboxylic</strong>$ $<strong>acid</strong>$= -cooh/ o double bonded (-oic acid)

Priority of organic molecules:

1. ==carboxylic acid==
2. ==aldehyde==
3. ==ketone==
4. ==alcohol (becomes hydroxyl-)==
5. ==alkene==

   this effects the order of naming them

   eg if there’s a carboxylic acid and an alcohol, the molecule becomes a hydroxyl… -oic acid

Types of formula

• %%displayed formula%%= the bond and atom in a molecule (the best one)
• %%skeletal formula%%= shows every bond except C and H
• %%structural formula%%= every atom no bonds, written order
• %%general formula%%= represents every member of a homologous series

^^Homolytic fission=^^

when a covalent bond breaks, each atom takes one of the shared electrons

-each now has a single unpaired electron so they are radicals

^^Heterolytic fission=^^

when a covalent bond breaks, one bonded atom takes both of the electrons

-this is the - ion and the other is the + ion

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free radical substitution

in the presence of uv, halogens react with alkanes to form haloalkanes

the no. of the step = how many reactions there are

eg. CH4 + Cl2 → CH3Cl + HCl

1. INITIATION

with uv, the covalent bond in a halogen is broken by homolytic fission = 2 halogen radicals

a. $Cl2 → Cl. + Cl.$

2. PROPAGATION

is a chain reaction

a. $CH4 + Cl. → .CH3 + HCl$ (1 carbon electron has nothing to bond to; is a radical)

$b. .CH3 + Cl2 → CH3Cl + Cl.$

$(in b, chlorine is the catalyst and CH3 is the intermediate)$

3. TERMINATION

$a. Cl. + Cl.→ Cl2$

$b. .CH3 + CH3 → C2H6$

$c. Cl. + .CH3 → CH3Cl$

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making more products?

during propagation, further halogen radicals can collide with the molecule substituting another H atom which produces a range of products

different positions?

the halogen can attach to wherever on the alkane and this forms a range of molecules

eg 1-bromoethane 4-bromoethane

%%Structural Isomerism%%

-molecules with the same molecular structure but a different structural formula

eg pent-1-ene and pent-2-ene

-chain isomerism = different arrangement of molecules skeleton

-position isomerism = different position on same functional group

-functional group isomerism = different functional group

%%Stereoisomerism%%

-same structural formula with arrangement of atoms in space

-E /Z = different groups which may be arranged differently due to restricted of c=c double bonds-

- optical isomerism = 2 molecules have a chiral centre/ mirror images

What effects the boiling point of alkanes?

-the chains are attracted by London forces (more = higher melting point)

-more surface contact (higher boiling point)

{{BRANCHED UNBRANCHED{{

-lower surface contact -high surface contact

-weaker London forces -strong London forces

-more volatile -less volatile

-efficient combustion

alkanes are very unreactive due to the strong C-H C-C bonds that have a low polarity

take part in both complete and incomplete combustion

BONDS

when atoms bond, their orbitals overlap producing bonding orbitals

%%SIGMA BOND%%

directly between 2 atoms by the overlap of orbitals

%%PI BOND%%

formed above and below the plane of the atoms by sideways overlap of p orbitals

ELECTROPHILLIC ADDITION

-alkene + bromine → bromoalkane

-bromine goes from orange to colourless

Curly arrow → movement of an electron pair in the creation or formation of a covalent bond

Electrophile → species that accepts a pair of electrons to form a covalent bond

Nucleophile → species that donates a pair of electrons to form a covalent bond

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MARKOWNIKOFF

• an unsymmetrical alkene will form 2 products
• major product forms from the more stable carbocation intermediate
• secondary carbocation is more stable than primary (more C)

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ethene addition reactions

$hydrogenation$

alkene + H2 → (Ni catalyst/ 150 ) alkane

$hydration$

alkene + steam → (h3po4) alcohol

polymerisation

-monomer units can form repeating polymers that can be written and demonstrated using n

the double bonds broken and stuck outside of the square brackets

-plastics are hard to break down and require sorting

options are

1.recycling 2.burning plastic to produce electricity 3.feedstock recycling

new alternatives are biodegradable and photodegradable