1s 2r
Tartaric acid has three stereoisomers: meso-tartaric acid and the two enantiomers, D-tartaric acid and L-tartaric acid.
Tartaric acid though it contains four chiral carbons will exists in three isomeric forms i.e., (+), (-), and meso.(+) and (-) tartaric acids are mirror images of each other and are hence enantiomers while meso is not a mirror image of either of them.
The chemical name for C4H4O6 is meso-tartaric acid.
Despite of containing two stereocenters (chiral centers) meso-tartaric acid is not chiral, because it is not stereospecific in the center of the molecule as a whole.A meso compound is superposable on its mirror image, and it does not produce a "(+)" or "(-)" reading when analyzed with a polarimeter.For example, of the 3 possible isomers of tartaric acid (depicted in 'Related links'), there is one mesocompound (the 2R,3S and 2S,3R isomers are equivalent) and two other optically active stereo-isomeric forms:dextrotartaric acid (L-(R,R)-(+)-tartaric acid) andlevotartaric acid (D-(S,S)-(-)-tartaric acid).Only in the meso compound an internal plane of symmetry exists, bisecting the molecule which is not present in the non-meso compounds. That is, on rotating the meso compound by 180° on a plane perpendicular to the screen, the same stereochemistry is obtained.
Tartaric acid is officially named: 2*,3*-dihydroxybutanedioic acid,Structural formula HOOC-C*H(OH)-C*H(OH)-COOHThe superscripted '*' denotes for three stereoisomeric differences:2R,3R- or2R,3S- or2S,3S-tartaric acid (unnatural form)The 2R,3R isomer (or L(+)-tartaric acid)is the natural most occurring one, while 2R,3S-tartaric acid is the socalled meso-tartaric acid because it is identical with its 'mirrored' 2S,3R-form.This stereo-isomeric problem was solved by the first practicing biotechnological engeneer of the french wine industry, the great Louis Pasteur.(citation:L. Pasteur (1848), "Mémoire sur la relation qui peut exister entre la forme cristalline et la composition chimique, et sur la cause de la polarisation rotatoire", Comptes rendus de l'Académie des sciences (Paris), vol. 26, pages 535-538)- translated title: "Memoir on the relationship which can exist between crystalline form and chemical composition, and on the cause of rotary polarization" -
Tartaric acid has three stereoisomers: meso-tartaric acid and the two enantiomers, D-tartaric acid and L-tartaric acid.
Tartaric acid though it contains four chiral carbons will exists in three isomeric forms i.e., (+), (-), and meso.(+) and (-) tartaric acids are mirror images of each other and are hence enantiomers while meso is not a mirror image of either of them.
The chemical name for C4H4O6 is meso-tartaric acid.
Despite of containing two stereocenters (chiral centers) meso-tartaric acid is not chiral, because it is not stereospecific in the center of the molecule as a whole.A meso compound is superposable on its mirror image, and it does not produce a "(+)" or "(-)" reading when analyzed with a polarimeter.For example, of the 3 possible isomers of tartaric acid (depicted in 'Related links'), there is one mesocompound (the 2R,3S and 2S,3R isomers are equivalent) and two other optically active stereo-isomeric forms:dextrotartaric acid (L-(R,R)-(+)-tartaric acid) andlevotartaric acid (D-(S,S)-(-)-tartaric acid).Only in the meso compound an internal plane of symmetry exists, bisecting the molecule which is not present in the non-meso compounds. That is, on rotating the meso compound by 180° on a plane perpendicular to the screen, the same stereochemistry is obtained.
There are many organic acids that are soluble though solid crystals:citric acid (Mp. 153 °C),tartaric acid (three Mp.: 171-174 °C (L-tartaric), 206 °C (DL, racemic), 146-148 °C (meso))malic acid (Mp. 130 °C),lactic (two different Mp.: L-lactic acid 53 °C, D: 53 °C and D/L, racemic: 16.8 °C).
Tartaric acid is officially named: 2*,3*-dihydroxybutanedioic acid,Structural formula HOOC-C*H(OH)-C*H(OH)-COOHThe superscripted '*' denotes for three stereoisomeric differences:2R,3R- or2R,3S- or2S,3S-tartaric acid (unnatural form)The 2R,3R isomer (or L(+)-tartaric acid)is the natural most occurring one, while 2R,3S-tartaric acid is the socalled meso-tartaric acid because it is identical with its 'mirrored' 2S,3R-form.This stereo-isomeric problem was solved by the first practicing biotechnological engeneer of the french wine industry, the great Louis Pasteur.(citation:L. Pasteur (1848), "Mémoire sur la relation qui peut exister entre la forme cristalline et la composition chimique, et sur la cause de la polarisation rotatoire", Comptes rendus de l'Académie des sciences (Paris), vol. 26, pages 535-538)- translated title: "Memoir on the relationship which can exist between crystalline form and chemical composition, and on the cause of rotary polarization" -
The stereochemistry of 2R,3R-2,3-dibromobutane is that both bromine atoms are on the same side of the molecule, making it a meso compound with a meso configuration.
Optical isomers are those which have one or more asymmetric carbon atoms their optical activity means a tendency to rotate the plane of plane polarized light but some of such molecules have an internal symmetry as meso form of Tartaric acid , this is the optical isomer of Tartaric acid but is optically inactive.
The product is optically inactive because the reaction results in a meso compound, which has an internal plane of symmetry that makes it superimposable on its mirror image. This cancels out any optical activity in the molecule, even though it has two chiral centers.
It means inter-, in between, in the middle meso : greek μεσο, μεσον
meso means middle
Meso-America means "Middle America" so Meso-Americans would be those living in that time period.