Racemic Mixture

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One of the most important physical properties of molecules is their chirality, or lack thereof which is known as achirality. Chirality is defined as the ability of a molecule to exist in two no superimposable images called enantiomers. This means that achirality is the opposite, in which molecule is superimposable on its mirror image. When two molecules are related in the fact that they are stereoisomers of each other, but are not mirror images. In nature chiral molecules do not exist in their enantiomerically pure form of R or S, but rather is a mixture that can be leaning towards one enantiomer or the other. When this mixture is a 50-50 mix of R and S it is called a racemic mixture. If there is an uneven mixture, say 60-40 this is called …show more content…
This relies on selective crystallization which is a result of the fact that large crystals are more stable than smaller ones. In addition to being more stable, the larger crystal is also more thermodynamically favorable because more stability correlates to a lower energy. This experiment also relies on the fact that individual enantiomers crystallize together in a single R or S crystal which is entirely up to luck. However, in the case of protein building is more favorable for amino acids to be enantiomerically pure because they have a packing effect that relies on this. Although effective, selective crystallization alone is not enough to cause chirality enhancement which means a base must be present in the reaction. The combination of an added base and selective crystallization allows for the enhancement of chirality in the system because according to Le Chatelier`s principle when there is a change in concentration of a chemical the equilibrium will shift to the right because the enantiomer of 1 is in excess. The base does not influence Le Chatelier`s principle, it only provides a catalyst to speed up a process that takes too long to naturally preform in a laboratory. Another catalyst that is used in the experiment described in the paper is glass beads and magnetic stirring, this speeds up the process because it …show more content…
The hydrogen that is the most acidic on the substitute is not the same as the most acidic hydrogen on L-alanine. Additionally, amino acids are more soluble in water than the surrogate which is bad for recrystallization because one wants a compound that is more insoluble so that it is easier to isolate from other compounds. This is another reason why a surrogate was used for the experiment rather than a natural amino acid. Typically, crystals of a racemic mixture are more favorable than crystals that are enantiomerically pure which is another reason why amino acids are interesting. Although the experiment is successful in being able to replicate enhanced chirality in a surrogate of an amino acid, when applying it to an amino acid in a prebiotic environment it proves to be lack luster. This is because there are too many differences between the surrogate and natural amino acids to make it a good surrogate including their difference in solubility, placement of acidic hydrogens, and acid-base catalyzation. Ignoring the faults of this experiment, another question one should ask themselves is how the original excess materialized. A controversial theory as to why this could be being that the amino acids could have come from space. One piece of convincing evidence that favors this theory is

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