Janic wrote:that is correct, the majority of the deviations of polarized light are levorotatory, but not all, whereas the synthesis products are levorotatory and dextrorotatory "by half"(I would say the L, but we may be correcting myself) ...
Hello Janic,
It would be nice if it were as simple but the prefix L or D has nothing whatsoever to do with dextrorotatory or levorotatory (the ability to rotate the plane of polarization of a light polarized to the left or to the right). It is true that it is tempting given that it corresponds to the initials. To know if a molecule is dextro or levogyre, it is necessary to make an experimental measurement with a machine called polarimeter which will measure the angle of deflection. On the other hand, to say if the molecule is L or D it suffices to know how to draw it according to the so-called Fischer representation. So a molecule D can be levorotatory ...
It's a very classic trap for first-year college students.
To answer Did67, in nature, the symmetry has been broken, it is still a subject of intense research. All the amino acids of nature are L, on the other hand, for sugars it is the configuration D which was selected therefore D glucose.
Afterwards, it gets even more complicated because D-glucose has 2 conformations called alpha and beta and then there is also the non-cyclic form so in all we have 5 different glucose, 3 of which are potentially present in equilibrium in a "natural" environment. .
Vegetable juice still has an advantage it is for people who do not like to eat vegetables, it allows them to lower impressive quantities of vegetables very quickly (we put a packet of spinach in a glass of 50 But clearly, if you like to eat vegetables, it's better to eat them whole with all the fiber.
