I'm really sorry if I get into trouble for posting outside links but there is literally nothing about it on this my favourite site.
Clear Web warning : https://chemistry.mdma.ch/hiveboard/crystal/000447791.html
Have a read and tell me what you think.
Clear Web warning : https://chemistry.mdma.ch/hiveboard/crystal/000447791.html
Have a read and tell me what you think.
I think it does, I've since read up on the subject and it looks like heat and light drive racemization, it's a concept used to date certain sites by studying fossils of marine animals and such, the principle being looking at the % of enantiomers can tell you how much time has passed since the animal died, since you know most amino acids are used in biological systems as levorotary form,You then look how much dextrorotary amino acid has been formed and from there you can estimate the age of the site, this is very roughly explained, just as proof of concept.So I was wrong just with the light part 
. Here's some sources, one of them claims, direct quote: At 160 °C, a racemic mixture is reached within 10–20 h, whereas in Arctic regions (−10 °C) racemic equilibrium requires 1–2 Ma.
G.H. Miller, ... S.J. Clarke, in Encyclopedia of Quaternary Science (Second Edition), 2013
Rainer Grün, in Encyclopedia of Archaeology, 2008
. Here's some sources, one of them claims, direct quote: At 160 °C, a racemic mixture is reached within 10–20 h, whereas in Arctic regions (−10 °C) racemic equilibrium requires 1–2 Ma.G.H. Miller, ... S.J. Clarke, in Encyclopedia of Quaternary Science (Second Edition), 2013
Rainer Grün, in Encyclopedia of Archaeology, 2008
"Racemization is the chemical reaction that interconverts an amino acid into its alternative enantiomer or mirror-image form. The rate at which racemization proceeds varies between amino acids according to the ability of R groups to stabilize a carbanion intermediate. The carbanion intermediate is the molecule formed when the hydrogen side chain is abstracted from an amino acid. In an ideal system, upon readdition of the hydrogen atom to the carbanion intermediate, there is an equal probability of l- and d-amino acid formation, and the forward and reverse reaction rates are equal. Under these conditions, d/l progresses from values near zero in modern tissues until d/l reaches unity at racemic equilibrium. A consequence of these conditions is the slowing of the racemization rate as the extent of racemization increases—the characteristic curvilinear trend produced when d/l ratios are plotted against linear time."
This is from Miller, I take from this that no, it dosen't have to be present.D-amino acids are so rare in nature that people tought they didnt even exist, so most living things use only L-amino acids in 100% proportion and they still racemize over time.
General Procedure for the Racemization Experiments. A
0.06 M solution of amine (100 mg) and thiol (1.2 or 0.2 equiv)
in benzene was refluxed for 2 h (stoichiometric condition) or 7
h (catalytic condition) in the presence of AIBN (an overall
quantity of 20 mol % of AIBN was divided into three equal
portions (when reaction time > 2 h) that were added successively each 2 h). After concentration, the residue was diluted
with HCl (1 M), and the solution was washed with Et2O. The
aqueous phase was basified with saturated sodium carbonate
and extracted with Et2O. The pure amine was isolated after
drying on MgSO4 and concentration.
0.06 M solution of amine (100 mg) and thiol (1.2 or 0.2 equiv)
in benzene was refluxed for 2 h (stoichiometric condition) or 7
h (catalytic condition) in the presence of AIBN (an overall
quantity of 20 mol % of AIBN was divided into three equal
portions (when reaction time > 2 h) that were added successively each 2 h). After concentration, the residue was diluted
with HCl (1 M), and the solution was washed with Et2O. The
aqueous phase was basified with saturated sodium carbonate
and extracted with Et2O. The pure amine was isolated after
drying on MgSO4 and concentration.