Racemic forms INDEX

Properties (Racemic form) Colorless liquid. Fp -75C, bp 119.3C, d 0.811 (20/20C), bulk d 6.75 lb/ gal (20C), refr index 1.4041 (40.5C), flash p 105F (40.5C) (OC), autoign temp 657F (347C). Soluble in water miscible with alcohol and ether. Combustible. 

Properties Colorless, transparent liquid terpene odor. D 0.8620-0.8645 (15.5/15.5C), refr index 1.4655-1.4670 (20C), boiling range 95% between 156 and 160C, fp -40C, flash p 90F (32.3C) (TCC), occurs in d-, and racemic forms. Insoluble in water soluble in alcohol, chloroform, and ether. 

Nucleosides in which the ribofiiranosyl oxygen is replaced by a methylene to result in a cyclopentane ring are referred to as carbocyclic nucleosides. The first such conopound was carbocyclic adenosine (1, aristeromycin), which was synthesized in its racemic form prior to isolation of the (-)-enantiomer from Streptomyces citricolor. The antiviral activity of has stimulated the search for other carbocyclic nucleosides that would display a more favorable therapeutic index. ... 

Br. CHa. CHa. CHa. CH(NHa). CH(CHa). CHa. CHjBr HBr. which on treatment with dilute alkali gives di-heliotridane (II). As the latter contains two asymmetric carbon atoms, two diastereoisomeric racemates might be produced in this reaction but only one was formed. It had density and refractive index in general agreement with those recorded for Z-heliotridane, as were also the melting points of characteristic derivatives. Density Df °0-902, refractive index wf, 1-4638 (<. with Adams and Rogers,3i Df ° 0-935, iijf° 1-4641), picrate, m.p. 234-6° (literature 232-6°), picrolonate, m.p. 162-3°, aurichloride, m.p. 200-1° (Konovalova and Orekhov give for these two constants 152-3° and 199-200° respectively). 

Another process that can account for the occurrence of D-amino acids in organisms is racemization, which involves the conversion of L-amino acids into their mirror-image D-form. Estuarine invertebrates have been found to have D-amino acids in their tissues as a result of this process (Preston, 1987 Preston et al., 1997). Rates of racemization of amino acids in shell materials, calibrated against radiocarbon measurements, have also been used as an index for historical reconstruction of coastal erosion (Goodfriend and Rollins, 1998). 

Prior to the 14th Collective Index, registry numbers were assigned to the (+/-)-forms (racemic mixtures) of compounds with one chiral centre. From the 14th Collective Index onward these assignments... 

C is formed from B on treatment with aqueous acid at room temperature. Compound C has no infrared absorption in either the 1620-1680-cm or the 359O-3650-cm region. It has an index ofhydrogen deficiency of 1 and has one chirality center but forms as the racemate. 

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