Organic Chemistry 1 Flashcards
What are hydrocarbons?
Compounds consisting of hydrogen and carbon only
What is the empirical formulae?
Simplest whole number ratio of atoms in a molecule
What does the structural formula show?
the arrangement of atoms in a molecule without showing the bond
Define skeletal formula
A type of formula which is drawn as lines, with each vertex being a carbon atom
Define homologous series
A series of organic compounds that have the same functional group, but each successive member differs by CH2
What is a functional group
a group of atoms responsible for the characteristic reactions of a compound
What is nomenclature
the set of rules that determine how different organic compounds should be named and how their formulas are represented
Give the suffix for a hydrocarbon with no double bond
(alk) ANE
Give the suffix for a hydrocarbon with a double bond
(alk) ENE
Give the suffix for an alcohol
-ol
Give the suffix for an aldehyde
-al
Give the suffix for a ketone
-one
Give the suffix for a carboxylic acid
-oic acid
What happens in an addition reaction
the reactants combine to form a single product
less products than reactants
What happens in a substitution reaction
it’s a reaction where there is the same number of products and reactants
What happens in an elimination reaction
it’s a reaction where you have more products than reactants
What happens in a reduction reaction?
A species gains at least one electron and it is reduced
What happens in an oxidation reaction?
A species loses at least one electron and is oxidised
What happens in a polymerisation reaction?
many monomers join to form a long repeating molecule, known as a polymer
What is hydrolysis
A reaction with water
What is the general formula for alkanes
CnH2n+2
Why are alkanes and cycloalkanes saturated hydrocarbons?
They don’t have a double bond
How are alkane fuels obtained?
From the fractional distillation, cracking and reforming of crude oil
Describe the process of fractional distillation of crude oil
1) The oil is preheated and passed into a column
2) The fractions condense at different heights and the temperature of columns decrease upwards
3) The separation of the fuels depends on the boiling point which depends on the size of the molecules. The bigger the molecule, the bigger the London forces
4) Similar molecules condense together and are collected at the same fraction
5) Small molecules condense at the top at lower temperatures and big molecules condense at the bottom at higher temperatures
What is cracking
The process of converting larger hydrocarbons to smaller molecules by breaking C-C bonds
What is the reforming of crude oil
the process of straight chained hydrocarbons being converted into branched hydrocarbons and cyclic hydrocarbons for combustion
What is the shape and angle of an alkane
Tetrahedral
109.5
Define structural isomerism
when molecules have the same molecular formula but different structural formula
What are the three ways in which structural isomers can be formed
Alkyl groups can be in different places
Functional groups can be in different places
Different functional groups
What are stereoisomers
Compounds with the same molecular formula but with a different arrangements of atoms in space
How is E/Z isomerism caused
by the limited rotation around a carbon-carbon double bond
When does an E isomer occur
When the groups attached to the c-c carbon bonds are on different sides
When does a Z isomer occur
When the groups attached to the c=c bond are on the same side
What are the products of a complete combustion reaction with alkane fuels
Carbon dioxide and water
What are the products formed of an incomplete combustion reaction when alkanes are used?
Water, carbon dioxide and carbon monoxide
What are the pollutants formed during the combustion of alkane fuels
Carbon monoxide Oxides of Nitrogen Sulfur Carbon particulates Unburned hydrocarbons
What is the environmental impact of:
1) carbon monoxide
2) soot
3) oxides of nitrogen
4) unbranched hydrocarbons
1) it’s toxic/ poisonous
2) asthma, cancer, global dimming
3) NO is toxic and can form smog// NO2 is toxic and acidic and forms acid rain
4) Contribute towards the formation of smog
How does the use of a catalytic converter solve some of the problems caused by pollutants
They use a rhodium catalyst to remove Nitrogen, CO and unburned hydrocarbons from the exhaust gases and turn them into less toxic products (CO2, N2 and H2O)
What are biofuels?
Fuels developed from renewable resources
Alcohols and biofuels are two examples of renewable plant based fuels
What are some advantages of biofuels
Reduces the use of non renewable fossil fuels
The use of biofuels is more carbon neutral
Fossil fuels can be used as feedstock for organic compounds
Less large scale population
What are some disadvantages of biofuels
Shortage of fertile soils
Reduction of rainforests, in order to make space for biofuels
Less food crops would be grown because crops for biofuel would be grown instead
What are radicals?
highly reactive, neutral species
Why do alkanes make good fuels?
They release a lot of energy when burned
How are halogenoalkanes formed?
Alkanes react with halogens in the presence of a UV light.
The UV light breaks down the halogen bonds producing reactive intermediates called free radicals
Describe initiation in terms of halogens
When the halogen is broken down in the presence of UV lights
Produces radicals from non radical species
Describe propagation in terms of halogens
A hydrogen is replaced and a halogen radical is reformed as a catalyst
To maintain the number of radicals
Describe termination in terms of halogens
Two radicals join to end the chain reaction and form a stable products
What can the propagation step do?
Continue many times to result in multiple substitutions
How can the reaction conditions be changed in order to limit the number of substitutions
Alter the reaction to favor the termination step
How is radical substitution limited in the synthesis of organic molecules
Because the reaction has the nature to produce multiple products
What is the general formula for alkenes
CnH2n
Why are alkenes and cycloalkenes classed as unsaturated hydrocarbons?
because they have at least one carbon-carbon double bond
What is the carbon double bond an area of?
high electron density
Why are carbon double bonds susceptible to attacks from electrophiles
Because of the area of high electron density
What does the carbon double bond consist of?
Normal covalent pi and sigma bonds
What is used to identify an alkene double bond?
bromine water
What colour change will appear in bromine water if there is an alkene ?
orange-brown to colourless
Why does a colour change occur if there is an alkene present in bromine water?
The C=C bond can ‘open up’ to accept bromine atoms and thus becomes saturated
What is meant by the term electrophile?
Electrophiles are electron acceptors and are attracted to high electron density.
What charge do electrophiles carry?
A full positive or slight positive charge
Alkenes undergo an addition reaction with hydrogen to form what?
a saturated compound
How can margarine be made via addition reactions?
Catalytic hydrogenation using a nickel powder
Through the addition reaction with hydrogen in the presence of a nickel catalyst the double bonds in these oils are broken and the molecules become saturated.
This increases the melting point of the oil so it becomes a solid.
The degree of softness of the margarine can be controlled by regulating the amount of hydrogenation
Describe how alkenes react with halogens to form halogenoalkanes
When the halogens approach the alkenes high electron density C=C bond, a dipole is induced.
The halogen nearest the C=C bond becomes partially positively charged and is able to act as an electrophile.
The electrophile then accepts a pair of electrons from C=C and forms a bond with one of the C atoms, creating a + carbon ion- carbocation.
Negative ions adds onto the carbocation, neutralising the molecule
What is halogenation?
When hydrogen halides add across the C=C bond in an alkene to form a halogenoalkane
Describe the addition reaction between alkenes and hydrogen halides to produce halogenoalkanes
Halogens are more electronegative than hydrogen, so the H-X bond is polar, the hydrogen atom has a partial positive charge (can act as an electrophile)
Electrophile then accepts a pair of electrons from C=C and forms a bond with one of the C atoms, creating a + carbon ion- carbocation.
Negative ions adds onto the carbocation, neutralising the molecule
When reacting alkenes with acids, is it an exothermic or endothermic reaction?
Exothermic
Describe the reaction between an alkene and an acid catalyst to form an alcohol
Alkenes undergo an addition reaction with water (steam) in the presence of a catalyst to form an alcohol- hydration reaction.
An alkene and steam enter a reactor (300 degrees and 60atms), with a phosphoric catalyst, This produces an alkene, steam and an alcohol. They are then condensed to produce alkene, water, and alcohol. They are then separated to produce water and the alcohol
Describe how alkenes react with potassium manganate to produce a diol
(In acid conditions)
Alkenes react with potassium manganate(VII) solution in the cold.
The potassium manganate solution is acidified with dilute acid, the purple solution becomes colourless
The manganate ions are strong oxidising agents and oxidise alkenes to diols.
What is heterolytic bond fission and what does heterolytic bond fission of a covalent bond result in?
Heterolytic fission is when a bond is broken and both electrons go to the same atom.
This results in the formation of ions
Describe the electrophilic addition reaction between alkenes and hydrogen halides
The pi bond (double bond) of the alkene is broken to form two single, sigma bonds.
One sigma bond connects to the H and the other to the X of the hydrogen halide.
*X referring to whatever the halide is
How do alkenes form polymers?
Through addition polymerisation
What happens to waste polymers?
Recycling
Used as feed stock for cracking
Incinerated to produce energy
How are scientists trying to limit the problems caused by polymer disposal?
Developing biodegradable polymers
Removing toxic waste gases caused by the incineration of plastics
How can polymers be useful for sustainability?
They have strong, non polar covalent bonds
Makes them useful for manufacturing everyday plastic products such as poly(ethene) shopping bags
What can halogenoalkanes be classified as ?
Primary , Secondary and tertiary
What does a reaction between a halogenoalkanes and aqueous potassium hydroxide produce ? What is the hydroxide ion acting as in this reaction ?
Produces alcohols, where the hydroxide ion is acting as the nucleophile
What is produced in a reaction between a halogenoalkanes with a aqueous sliver nitrate in ethanol , where water acts as a nucleophile ?
Precipitates are produced as halide ions
What is produced when halogenoalkanes reacts with potassium cyanide ? ( cyanide ion acts as a nucleophile )
Nitriles are produced
What is produced in a reactions between a halogenoalkanes with ammonia ? ( ammonia molecule acts as a nucleophile )
Primary amines are produced
What is a Amine?
amine is a compound with a functional group of a basic nitrogen with a lone pair , a derivative from ammonia , same structure as ammonia (NH3) but with a lone pair
What is produced in a reaction with a halogenoalkanes with ethanolic potassium hydroxide ? ( hydroxide ion acts as a base )
a Alkene is produced
What is the most reactive halogenoalkane between primary , secondary and tertiary ?
most reactive Tertiary Secondary Primary least reactive
In terms of bond enthalpy which alkane is more reactive , Chloro- , Bromo- and Iodo-
most reactive Chloride Bromide Iodide least reactive
What is produced in a nucleophilic substitution mechanism , with a primary halogenoalkane , aqueous potassium hydroxide , ammonia ?
an alcohol is produced
What can alcohols be classified ?
primary , secondary and tertiary
What happens when alcohols react with the oxygen in the air ?
Complete combustions happens to produce water and carbon dioxide
what happens when a alcohol reacts with a halogenating agent ?
when the alcohol is reacted with HBR or HCL undergo a nucleophilic substitution to get a alkyl halide and water
what is the alcohol relative reactivity order ?
most reactive tertiary secondary primary least reactive
what is the hydrogen halide reactivity order?
Most reactive HI HBr HCL HF least reactive
What is formed when a reactions happens to potassium dichromate in a dilute sulfuric acid to oxidise primary alcohols
aldehydes or carboxylic acids depending on the reaction conditions , its then further oxidised from a aldehyde to a acid
what is produced when a alcohol reacts with a concentrated phosphoric acid ?
an alkene is formed by elimination reaction
what is heating under reflux ?
a technique used to apply heat energy to a chemical reaction mixture over an extended period of time
what is extraction with a solvent in a separating funnel ?
a piece of laboratory glassware used in liquid - liquid extractions to separate the components of a mixture into two immiscible solvent phases of different densities
