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It has chemical formula C 5 H 10 O 5. Two enantiomers are possible, d-ribulose (d-erythro-pentulose) and l-ribulose (l-erythro-pentulose). d-Ribulose is the diastereomer of d-xylulose. Ribulose sugars are composed in the pentose phosphate pathway from arabinose. [1] They are important in the formation of many bioactive substances.
Several isomers exist with the formula H−(C=O)−(CH 2)−(CHOH) 3 −H, but in deoxyribose all the hydroxyl groups are on the same side in the Fischer projection.The term "2-deoxyribose" may refer to either of two enantiomers: the biologically important d-2-deoxyribose and to the rarely encountered mirror image l-2-deoxyribose.
Two older prefixes still commonly used to distinguish diastereomers are threo and erythro. In the case of saccharides, when drawn in the Fischer projection the erythro isomer has two identical substituents on the same side and the threo isomer has them on opposite sides. [ 7 ]
The natural isomer is D-erythrose; it is a diastereomer of D-threose. [3] Fischer projections depicting the two enantiomers of erythrose. Erythrose was first isolated in 1849 from rhubarb by the French pharmacist Louis Feux Joseph Garot (1798-1869), [4] and was named as such because of its red hue in the presence of alkali metals ...
Threose is a four-carbon monosaccharide with molecular formula C 4 H 8 O 4.It has a terminal aldehyde group, rather than a ketone, in its linear chain and so is considered part of the aldose family of monosaccharides.
Four isomers of methylphenidate are possible, since the molecule has two chiral centers. One pair of threo isomers and one pair of erythro are distinguished, from which primarily d-threo-methylphenidate exhibits the pharmacologically desired effects. [119] [149] The erythro diastereomers are pressor amines, a property not shared with the threo ...
The second reaction is the organic reduction of 1,2-diphenyl-1-propanone 2 with lithium aluminium hydride, which results in the same reaction product as above but now with preference for the erythro isomer (2a). Now a hydride anion (H −) is the nucleophile attacking from the least hindered side (imagine hydrogen entering from the paper plane).
Its use as a food dye was legalized in the US by the Pure Food and Drug Act of 1906. [6] By early 1920s, it was produced mainly for the food industry, [7] with 2,170 pounds (0.98 t) made in America in 1924, [8] rising to 9,468 pounds (4.29 t) in 1938 [9] and approximately 50 tons in 1967. [10]