Organic Chemistry Unknown Information (not including reactions)

  • Created by: Lotto65
  • Created on: 28-02-18 10:16
What bond does organic chemistry study primarily?
-C-H bond
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What is catenation?
The way carbon atoms can join together to form rings and chains
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What is the main source of carbon compounds?
Crude oil (petroleum)
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Give some uses of carbon compounds in organic synthesis reactions to make more complex molecules?
Medicines, cosmetics and polymers
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What shape are alkanes?
Straight chains
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What is the name of the alkane with 20 carbon atoms?
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What is a hydrocarbon?
A compound containing only carbon and hydrogen
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What is the empirical formula?
The simplest whole number ratio of elements present in a compound
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What is the molecular formula?
The total number of atoms of each element present in a molecule of the compound
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What is the shape of each carbon molecule in an alkane (four electron domains)?
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What are other words for structural formula?
Displayed or graphic formula
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What is the difference between a structural and condensed structural formula?
Structural has bonds drawn at 90 degree angles. Condensed just writes each molecule in order of the compound
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Name three other ways of showing the structure of a compound on the computer
Stick model; Ball and stick model; Space-filling model; Newman projection
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What is a homologous series?
A series of compounds that have the same functional group.
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What separates each compound in a homologous series?
A common structural unit (normal -CH2-)
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What does a functional group do?
Gives the molecule its chemical properties and is the reactive part of the molecule
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What are features of a homologous series?
Can be given a general molecular formula; Have similar chemical properties; Show a graduation in physical properties like boiling point
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Which homologous series do you have to specify the position of the functional group?
Alkenes, Alkynes, alcohols, ethers, halogenoalkanes, ketones, amines
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What do amines smell like?
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What is the structure of benzene?
C6H6 so a hexagonal ring of carbon atoms each single bonded to a hydrogen atom
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What does aromatic mean?
A compound contains a benzene ring
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What does aliphatic mean?
A compound does not contain a benzene ring
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What is the functional group in aromatic compounds?
The benzene ring because it performs characteristic chemical reactions
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What is a phenyl group?
A benzene ring missing a hydrogen atom (C6H5)
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How do you write the structural formula of an aromatic compound?
Write the phenyl group first and then the attachment
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As the number of carbon atoms in a homologous series increases, what happens to the boiling point?
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When comparing compounds within a homologous series, what can you look at?
Molecular mass differences
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When comparing homologous series, what should you look at instead of molecular mass?
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What has a higher boiling point and solubility out of alcohols and ethers? Why?
Alcohols. Hydrogen bonding
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What does IUPAC stand for?
International union of pure and applied chemistry
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When you state the position of the functional group or side groups, how do you choose the number?
The number that is the lowest (not the sum)
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How are substituent groups arranged in a name?
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What is used between numbers in a name?
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What is used between numbers and letters in a name?
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What can you do with the name if all the substituent groups are the same?
Merge them e.g. 2,6,6-trimethyloctane
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If you have a functional group and substituent groups, which one has the lowest number when naming the compound?
Functional group
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What do you add in if an alkene has three double bonds?
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What is the general formula for alcohols and ethers?
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What is the name of the shorter alkyl group with the oxygen atom in an ether?
Alkoxy group
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What is the alkoxy group treated as?
A substituent group
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What is the condensed structural formula for the aldehyde functional group?
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Is the ketone functional group ever at the end of a chain?
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How do you name a carboxylic acid with two functional groups?
e.g. Butanedioic acid
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How is the ester functional group shown in a condensed structural formula?
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Give some uses of esters?
Artificial flavours and odours in sweets; plasticisers added to PVC to increase flexibility
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What is the fear of phthalate esters like DEHP?
They cause cancer
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When finding the longest carbon chain in an ester, what is the requirement for the alkyl group?
The last carbon in the longest carbon chain must be attached to the -O of the functional group
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What determines if an alcohol or halogenoalkane is primary, secondary or tertiary?
How many carbons are attached to the carbon with the functional group
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Which group shows a primary amine?
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Which group shows a secondary amine?
-NHR (R is an alkyl group so the nitrogen is attached to two carbon atoms)
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Which group shows a tertiary amine?
-NR2 (two alkyl groups so nitrogen is attached to three carbon atoms)
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What are structural isomers?
Two or more compounds that have the same molecular formula but different structural formulas
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Are bent molecules isomers?
No because the atoms are joined together in the same way
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Is there lots of rotations around a single bond?
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Why do branched chain isomers have lower boiling points?
Chains cannot get as close to each other so cannot pack as tightly together, meaning London forces are weaker
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What can isomers contain sometimes?What are these isomers called?
Different functional groups. Functional group isomers
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Alcohols are functional group isomers with...
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Carboxylic acids are functional group isomers with...
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Aldehydes are functional group isomers with...
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Who discovered benzene?
Michael faraday
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When was benzene discovered?
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What was the proposed structure kekule benzene?
A hexagonal ring of 6 carbon atoms each attached to one hydrogen atom and alternating single and double bonds between the carbon atoms. Planar structure
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What were names given to the kekule benzene molecule?
Cyclohexa-1,3,5-triene or 1,3,5-cyclohexatriene
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What is the new proposed structure of benzene?
A planar hexagonal ring of 6 carbon atoms that only form 3 bonds each and bond to one hydrogen atom. The remaining 6 electrons form a delocalised pi system in the centre (spread across whole ring)
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What causes the ring of electrons in benzene?
Overlapping p orbitals side-on
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What is the danger with benzene?
It is a human carcinogen and causes leukemia
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What is the main source of exposure to benzene?
Car exhaust fumes and in some industrial processes, risking health of people at work
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What are the bond lengths in the new benzene molecule?
All are the same length exactly half way between a single and double bond
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Why is it believed that the bond lengths in benzene are between a double and single bond?
Between each pair of carbon atoms, it is thought that there are an average 3 electrons (2 from the single bond and 1 from the delocalised electron) which is between 4 electrons for a double bond and 2 electrons for a single bond
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What does the delocalisation of electrons give benzene?
More stability
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What is the thermochemical evidence to support the structure of benzene?
Hydrogenation of cyclohexene (1 double bond) has an enthalpy change of -120kJmol-1. Kekule benzene has 3 double bonds so has enthalpy change of -360kJmol-1. Hydrogenation of benzene is in between with -205kJmol-1
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What about isomers leads to the new benzene structure evidence?
Kekule benzene is expected to have 4 isomers because the chlorine atoms can be separated by either a single or double bond. However, only 3 isomers of new benzene have been found
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What evidence is there of the structure of benzene from chemical reactions?
Does not undergo addition reactions under normal conditions and does not decolorise bromine water as kekule benzene would be expected to
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Why does benzene not undergo addition reactions under normal conditions?
This would destroy the delocalised system and benzene would lose its extra stability
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What are the four pieces of evidence supporting the new structure of benzene?
Physical: Isomers and bond lengths. Chemical: Chemical reactions and hydrogenation
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What is the polarity of alkanes?
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What are the properties of alkanes and why?
Volatile (evaporate easily) because only have London dispersion forces. Insoluble in water because non-polar
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Why are alkanes unreactive?
C-C and C-H bonds are high strengths bonds so it is energetically unfavourable to break them. These bonds are also non-polar bonds so do not attract polar molecules or ions
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What is a substitution reaction?
When an atom or group in a molecule is replaced by a different atom or group
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What is the polarity of alkenes? What intermolecular forces do they have?
Non-polar so only London forces
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What is an alkene's solubility?
Insoluble in water because they are non-polar
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Why are alkenes more reactive than alkanes?
Double bond is a region of high electron density and attracts electrophiles. The pi element of the double bond is weaker than a single bond sigma bond so the double bond is not double the strength of a single bond
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What is an electrophile?
Positively charged ion or positive end of a dipole attracted to a region of high electron density and accepts a pair of electrons to form a covalent bond
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What type of acid is an electrophile?
Lewis acid
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Give some uses of polyethene
Washing up bowls, plastic bags, plastic bottles
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Give some uses of polychloroethene
Insulation for electric cables, window frames
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Give some uses of polypropene
Car bumpers and carpet fibres
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What are the two main issues with polymers?
They are produced by crude oil which is a limited resource. They are non-biodegradable
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What is a nucleophile?
A molecule or negatively charged ion that has a lone pair of electrons and is attracted to highly positively charged regions in a molecule (low electron density) and donates its electron pair to it
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What sort of hybrid is benzene?
Resonance hybrid (a hybrid of its resonance structures)
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Why is the bond order of benzene 1.5?
The pi component of the double bond is shared between a C-C bond
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Where is there delocalisation in benzene?
Across the whole structure
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Why is benzene susceptible to attack by electrophiles?
The delocalised pi system has a high electron density
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What are stereoisomers?
Have the same structural formula but the atoms are arranged differently in space
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What is cis-trans isomerism?
Two compounds have the same structural formula but the groups are arranged differently in space around a double bond or in a ring
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Why can the atoms not rotate in a double bond?
The pi component would have to be broken for rotation this involves a lot of energy
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What is required for cis-trans isomerism to occur?
Two different groups on both sides of the double bond
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What is the issue with the cis-trans isomerism system?
Gives no indication into the structure of molecules with four separate groups around the double bond
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What is the name of the set of rules involved in the E/Z naming system?
Cahn-Ingold- Prelog priority rules
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How does the E/Z naming system work?
Higher priority is given to the atoms of either side of the double bond with a higher atomic number
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What letter is given if the higher priority atoms are on the same side of the double bond?
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What letter is given if the higher priority atoms are on different sides of the double bond?
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How many groups attached does a double bond count as in the E/Z naming system?
Two groups
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Do cis or trans isomers have a higher boiling point? Why?
Cis because they can be polar while trans isomers have dipoles that cancel out. Being the same molecular mass means same strength London forces but cis ones have added permanent dipole forces
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What is the difference in terms of number of hydrogen atoms between cycloalkanes and normal alkanes?
Cycloalkanes have two less hydrogen atoms (aka they have the general formula of alkenes but with only single bonds)
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In a structural formula, bold black triangles show what? What about dashed triangles?
Bold black triangles = Coming out the page. Dashes triangles = Into the page
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Can atoms/ groups rotate in the ring structure of a cycloalkane?
No - requires the breakage of the ring which requires a lot of energy
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How are cis-trans isomers possible in cycloalkanes?
Substituted cycloalkanes
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What is required for cis-trans isomerism to occur in cycloalkanes?
At least two carbon atoms must have two different groups attached
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What are conformational isomers?
Forms of the same molecule that have different conformations due to rotation about a sigma bond
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Conformational isomers have a low barrier to rotation (they interconvert). Why? What does this mean in terms of isolating a specific isomer?
Changes in rotation between atoms/groups and the freedom of rotation around the sigma bond make it hard to isolate a specific conformational isomer
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Why do trans isomers have a lower potential energy?
Atoms/groups are further apart so less repulsion between them
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What factors affect the rate of conformational isomer interconversion?
Barrier to rotation and temperature
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Name two forms of conformational isomer
Chair and boat form
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Do chemical bonds need to be broken to interconvert conformational isomers?
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Do chemical bonds need to be broken to interconvert configurational isomers?
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What is optical isomerism?
Molecules have the same structural and molecular formula but individual groups are arranged differently in space and individual isomers are non-superimposable mirror images
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What does it mean if a carbon compound has three groups around a carbon atom instead of four?
It is superimposable
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What do we call the chiral carbon atom?
Asymmetric carbon atom
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If a cyclic compound has a plane of symmetry, does it show optical isomerism?
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What sort of light is rotated in enantiomers?
THE PLANE OF plane-polarised light
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What is involved in a simple polarimeter?
Light --> Polarising filter --> Sample tube --> Polarising filter with scale
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Why do you use a sodium lamp for polarimeters?
Produces light of one wavelength
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How do you use a polarimeter?
Put the solvent that the sample will be dissolved in into the sample tube and rotate the polarising filter at the end until no light can be seen (filters are crossed). Add sample with solvent and move filter again and measure angle difference
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What is a racemic mixture?
An equimolar mixture of two enantiomers of a chiral compound
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Is a racemic mixture optically active or inactive? Why?
Inactive as rotation effects cancel each other out
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Why is it so easy to produce a racemic mixture from a chiral compound?
The enantiomers are equally stable so both will be produced
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How can you make a specific enantiomer?
Use a carefully designed synthetic pathway to get that isomer or obtain it from the racemic mixture
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What are diastereomers?
Stereoisomers that are not mirror images of each other
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Give an example of a diastereomer?
Cis-trans isomers
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What could create a diastereomer?
More than one chiral centre
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What is the same in enantiomers?
Chemical properties for reactions with optically inactive compounds and physical properties like melting point, boiling point and solubility
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Diastereomers have different...
Chemical and physical properties
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What did thalidomide do?
Sedative and relieved sickness so was used for morning sickness in women in first three months of pregnancy
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What happened as a consequence of thalidomide?
Thousands of children born with missing or malformed limbs and died in infancy
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What was wrong with thalidomide?
It was a racemic mixture and the S-enantiomer was teratogenic (toxic to foetuses)
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Why could you not give just the R-enantiomer of thalidomide instead?
They interconvert in the body to produce the racemic mixture
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What testing must occur now when marketing a racemic mixture drug?
Testing on the racemic mixture and the individual enantiomers
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What do pharmaceutical companies do instead with drugs?
Do not develop the racemic mixture but separate or synthetically produce one active enantiomer and develop that
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Other cards in this set

Card 2


What is catenation?


The way carbon atoms can join together to form rings and chains

Card 3


What is the main source of carbon compounds?


Preview of the front of card 3

Card 4


Give some uses of carbon compounds in organic synthesis reactions to make more complex molecules?


Preview of the front of card 4

Card 5


What shape are alkanes?


Preview of the front of card 5
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