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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 ...
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).
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.
[159] [162] [163] [164] The erythro isomer was eliminated, and now modern formulations of methyphenidate contain only the threo isomer in a 50:50 mixture of d- and l-isomers. [159] Methylphenidate was first used to allay barbiturate-induced coma, narcolepsy and depression. [165] It was later used to treat memory deficits in the elderly. [166]
In one isomer the CO ligands are terminal. When a pair of CO are bridging, cis and trans isomers are possible depending on the location of the C 5 H 5 groups. [7] Another example in organometallic chemistry is the linkage isomerization of decaphenylferrocene, [(η 5-C 5 Ph 5) 2 Fe]. [8] [9] Formation of decaphenylferrocene from its linkage isomer
1.911 563 813 932 49 × 10 29: 1.074 915 681 871 30 × 10 34: C 76 H 154: n-hexaheptacontane 77 5.208 741 952 489 07 × 10 29: 3.420 121 950 214 83 × 10 34: C 77 H 156: n-heptaheptacontane 78 1.419 908 915 343 95 × 10 30: 1.088 656 356 286 10 × 10 35: C 78 H 158: n-octaheptacontane 79 3.872 282 575 137 01 × 10 30: 3.466 709 375 563 28 × 10 ...
Its strange that this decription of the definition of a diastereomer does not mention E/Z alkene isomers!--175.38.163.188 18:26, 15 August 2013 (UTC) Cis–trans isomerism does not involve chirality. So the E and Z forms are isomers, but not enantiomers, and as such can't be diastereomers either.