organic chem

Skeletal formula definition

the simplified organic formula, shown by removing hydrogen atoms from alkyl chains, leaving just a carbon skeleton and associated functional groups e.g. for butan-2-ol:

Homologous series definition

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

Functional group definition

a group of atoms responsible for the characteristic reactions of a compound

Alkyl group formula

CnH2n+1

Aliphatic definition

a compound containing carbon and hydrogen joined together in straight chains, branched chains or non-aromatic rings

Alicyclic meaning

an aliphatic compound arranged in non-aromatic rings with or without side chains

Aromatic meaning

A compound containing a benzene ring

What is a benzene ring

An aromatic functional group characterized by a ring of six carbon atoms, bonded by delocalised pi electron system

Saturated meaning

Only contains single carbon-carbon bonds

Unsaturated

The presence of multiple carbon-carbon bonds including C=C C=-C and aromatics rings

Structural isomer definition

Compounds with the same molecular formula but a different structural formula

Alkane definition

Saturated hydrocarbons containing single C-C and C-H sigma bonds

Why is there a tetrahedral shape around each carbon in an alkane

4 bonding regions and zero lone pairs result in equal repulsion and a 109.5 degree between each carbon

Why does boiling point increase in longer chain alkanes

higher surface area so more contact points so more london dispersion forces

Why does boiling point decrease with more branching

Branched alkanes has relatively small surface area for contact points, so less London dispersion force act among molecules

Why do alkanes have relatively low reactivities?

Due to the strong C-C and C-H bonds in the molecules that require a lot of energy to overcome or in the presence of strong catalysts

Complete combustion formula

Alkane+oxygen→ carbon dioxide+ water

Incomplete combustion formula

Alkane+oxygen→ carbon monoxide/soot+ water

sigma bond

head on overlap of two p orbitals

pi bond

adjacent p orbitals overlap in a sideways orientation forming a cloud of electron density above and below the plane

what is a double bond made of

sigma and pi bond

is a sigma or pi bond stronger

sigma

what bond breaks with a double to single bond

pi bond as it is weaker

free radical mehcanism steps

initiation with Uv light to form radicals

propagation in which radicals and pairs make radicals and pairs

termination starts with radicals ends with pairs

stereoisomer definiton

same structural formula but different arrangement of atoms in space

E/Z isomerism requirements

C=C double bond, different groups attatched to each carbon of the double bond

position isomers

structural isomers that can be viewed as differing only on the position of a functional group, substituent, or some other feature on the same "parent" structure

chain isomers

made up of two or more carbon or other compounds with the same molecular formula but different atomic arrangements, or branches

functional group isomers

molecules with the same molecular formula, but different functional groups

naming E/Z isomers rules

draw line in middle of C=C, assign priority on each side acoridng to alphabetical (directly bonded to C). same side Z opposite E

why do E/Z isomers need a double bond

because it restricts free rotation and means the groups attatched to the carbons can’t move

cis-trans isomers

a type of E/Z where two of the substituent groups on the C=C bond are the same

electrophilic meaning

electron pair acceptor

nucleophilic meaning

electron pair donor

why are alkenes more reactive than alkanes

-pi bonds are weaker so need less energy to overcome

-high electron density of C=C

what is a curly arrow used for?

showing where an electron pair is going. go from high to low electorn density

what is electrophilic addition

a reaction in which a substrate is initially attacked by an electrophile, and the overall result is the addition of one or more relatively simple molecules across a double bond

what is a reaction mechanism

a series of steps that show how a reaction takes place

Marvovnikoff’s rule

during electrophilic addition to alkenes/alkynes the h atom in the electrophile will be added to the C with less C/more H

primary carbocation 1°

the carbon which carries the positive charge is only attached to one other alkyl group

secondary (2°) carbocation

the carbon with the positive charge is attached to two other alkyl groups, which may be the same or different

tertiary (3^o) carbocation

the positive carbon atom is attached to three alkyl groups

order of stability for carbocations and why

tertiary most primary least bceause the more chains the bigger the inductive effect

what is the inductive effect

The effect on electron density in one portion of a molecule due to electrophilic or nucleophilic groups elsewhere in the molecule

what determines the major product adding a hydrogen halide to an alkene

the C bonded to the least Cs

what happens in heterolytic fission

the pair of shared electrons is taken by one of the atoms

what happens in homolytic fission

the pair of electrons is split between the separated atoms

benefits of polymer use

readily availabile, cheap, more convenient than glass bottles, metal dustbins, paper bags and cardboard packaging, lack of reactivity

disadvantages of polymer use

challenge in disposal

mostly non-biodegradeable

killing marine life

recycling evaluation

reduces environmental impact

conserves finite fossil fuels

decreasing landfill buildup

sorted by type. can’t mix

chopped to flakes, washed, dried, melted

products may be weaker/less quality

PVC recycling evaluation

disposal and recycling is hazardous due to chlorine content and additives

landfill not sustainable

when burnt HCl gas is released it’s corrosive

releases other pollutants like toxic dioxins

new solvents that dissolve polymers and high grade PVC is recovered by precipitation. solvent reusable

waste polymers as fuel evaluation

some difficult to recycle

high stored energy value

incinerated to produce heat, generating steam to drive a turbine, producing electricity

feedstock recycling evaluation

the chemical and thermal process that can reclaim monomers gases and oils from waste polymers

products resemble those produced from crude oil in refineries

can be used as raw materials for new polymers

major benefit is that it can handle unsorted and unwashed polymers

bioplastics

produced from plant starch cellulose, plant oils, and proteins

renewable and sustainable alternative

protects environment and valuable oil reserves

biodegradeable polymers

broken down by microorganisms into water CO2 and biological compounds

usually made from starch/cellulose OR additives that alter the structure of traditional polymers so microorganisms can break them down

biodegradeable polymers EXAMPLES

poly(lactic acid)

plant starch/cellulose

sugar cane fibre

photodegradeable polymers

oil based

weakened by absorbing light to start degradation

general formula def

the simplest algebraic formula of a member of a homologous series) e.g. for an alkane: CnH2n+2

structural formula definition

the minimal detail that shows the arrangement of atoms in a molecule) e.g. for butane: CH3CH2CH2CH3 or CH3(CH2)2CH3

displayed formula definition

the relative positioning of atoms and the bonds between them e.g. for ethanol:

ozone depletion reaction

Cl + O3 → ClO + O2

ClO + O3 → Cl + 2O2

overall: 2O3 → 3O2

what is a CFC

chlorofluorohydrocarbon compound containing Cl, F, C, H

what is ozone

a form of oxygen O3

where is the ozone layer found

the stratosphere

what does ozone do

absorbs harmful Uv radiation which can damage DNA and cause skin cancer

what do CFCs do to ozone

CFCs break down from UV in stratosphere to form Cl radicals by breaking C-Cl. free radical chain reaction

why can one Cl radical destroy many ozone molecules

chain reaction which the radicals are not used up (they are reformed)

what is the montreal protocool

1987 many countries signed deal to ban CFC use. use has fallen dramatically. most effective environmental actions ever. ozone no longer depleting, [predicted to rise again

CFC alternatives

chemicals that do not contian chlorine. 1,1,1,2-tetrafluoroethane for fridges

butane for aerosol propellant. can’t produce Cl radicals as no Cl.

still greenhouse gases, so problem there

quickfit apparatus

-1 round bottom or pear shaped flask

-2 receiver

-3 screw tap adapter

-4 condenser

-5 still head

reflux setup

-bunsen burner/water bath if under 100C/ heating mantle for flammable liquids

-antibumping granules

-thin layer of grease to ground glass joints

-condenser upright

-clamp loosely

-no stopper or it will explode

-top tube linked to sink, bottom tube to tap

distillation setup

-purifies from incomplete reaction/by-products

-round bottom or pear shaped flask

-condenser

-rubber tubing

-heat source

-stands and clamps

-screw cap adaptor

-receiver adaptor

-still head

-thermometer

what is a receiver adaptor

what is a condenser

what is a screw cap adaptor

what is a still head

T shaped

what is a heating mantle

separating after organic synthesis of a liquid

-water may be obtained

-clear separation of 2 layers

-identify organic product by adding distilled water and seeing which layer increases - that is water

-conical flasks for collection

drying agents

-anhydrous inorganic salt

-CaCl2: specifically hydrocarbons

-CaSO4 and MgSO4 general drying agents

removing traces of water from organic synthesis

-drying agent

-add into flask with spatula

-add stopper, swirl

-if solid lump, water remains. add more

-add more until soft fine powder

-decant liquid into another flask. should be clear

why would you need to redistillate

-organic liquids can have close boiling points so impurities

-apparatus cleaned dried set up again

-only collect product with desired boiling point

-narrower bp range → purer product

do alcohols with the same chain length have a higher or lower bp and mp that alkanes and why

they have a higher b.p and m.p than alkanes because of their polar -OH group which forms H bonds

what’s more volatile alcohol or alkanes and why

alkanes because they only have weak london forces but alcohols have hydrogen bonds

what is a primary alcohol

an alcohol whose -OH group is bonded to a carbon only directly bonded to 1 other methyl groups

what is a secondary alcohol

an alcohol whose -OH group is bonded to a carbon directly bonded to 2 other methyl groups

what is a tertiary alcohol

an alcohol whose -OH group is bonded to a carbon directly bonded to 3 other methyl groups

oxidising agents for alcohols

-acidified potassium dichromate (VI) or Cr2O72-/H+, K2Cr2O7, H2SO4.

-represented as [O] in equation

-heat in water bath

product of oxidation of primary alcohols

aldehydes under heat with agent. further oxidation. under reflux produces carboxylic acids

product of oxidation of secondary alcohols

ketones

how to avoid further oxidation of aldehydes

heat while distilling to remove products from reaction vessel before they can react further

oxidation of tertiary alcohols

not possible

dehydration of alcohols conditions

acid catalyst - H3PO4 or H2SO4 and heat

dehydration of alcohols product

alkenes

alcohol substitution with halide ions conditions

halide ions in the presence of acid catalyst such as (NaBr and H2SO4)

halide substitution of alcohols product

haloalkanes

haloalkane hydrolysis product

alcohol

what primary haloalkane hydrolyses fastest

C-I, C-Br, C-Cl, C-F in order of fastest to slowest. because bond enthalpy decreases down the group due to larger atomic radius, more shielding, less charge

organic synthesis

the preparation of complex materials from simple starting materials

alkene functional group

alcohol functional group

-OH