Basic Organic Chemsitry And Isomerism Flashcards
What is a homologous series
A group of organic compounds which have the same general formula eg alkanes
What is a functional group
A reactive part of a molecule
What are stereo isomers
They have the same structural formula but a different arrangement of atoms in space
Describe stereoisomerism
Can twist and rotate a molecule any way around a single bond. But a double bond has a fixed position-you can’t rotate the rest of the molecules around it. Because of the lack of rotation around the double bond, some alkenes have stereoisomers. Stereoisomers happen when each double-bonded carbon atom has 2 different atoms or groups attached to it. Get E or Z isomerism
What are the three types of structural isomers
Chain isomers
Positional isomers
Functional group isomers
What are chain isomers
Have different arrangements of the carbon skeleton. Some are straight chains and others branched in different ways
What are positional isomers
Have the same skeleton and the same atoms or groups of atoms attached. The difference is that the functional group is attached to a different carbon atom
What are functional group isomers
Same atoms arranged into different functional groups
What does nomenclature mean
Naming organic compounds
What is the general formula of the alcohol homologous group
CnH2n+1OH
What are optical isomers
Mirror images of each other. Optical isomerism is another type of stereoisomerism. Stereoisomers have the same structural formula but have their atoms arranged differently in space
What is a chiral (asymmetric) carbon atom
One that has four different groups attached to it. Possible to arrange the groups in 2 different ways around the carbon atom so that 2 different molecules are made, these molecules are called enantiomers or optical isomers. The enantiomers are mirror images, no matter which way you turn them they can’t be superimposed
What is another name for optical isomers
Enantiomers
What does it mean if a molecule can be superimposed
They’re achiral and there’s no optical isomerism
Optical isomers are optically active. Explain
They rotate plane-polarised light (which only vibrates in one direction). One enantiomers rotates it in a clockwise direction, and the other rotates it in a clockwise direction
What is a racemate/ racemic mixture?
It contains equal quantities of each enantiomer of an optically active compound. Racemate don’t show any optical activity, the 2 enantiomers cancel each other’s light rotating effect. Chemists often react 2 achiral things together and get a racemic mixture of a chiral product. This is because when the 2 molecules react there’s an equal chance of forming each of the enantiomers. You can modify a reaction to produce a single enantiomer using chemical methods but it’s difficult and expensive
Suggest one advantage and one disadvantage for using a racemic mixture rather than a single enantiomer in medicines
Cheaper as no need to separate enantiomers
May be side effects from one of the enantiomers in the mixture/ only half of the product works
How can a pair of stereoisomers be distinguished
Using a polarimeter, plane polarised light will be rotated in opposite directions
