Thiourea adducts

FIGURE 3.6 Chiral helical hexagonal structure of urea and thiourea adducts. A chiral guest generates one helical form. (Straight chain alkyl guests fit in the urea adduct channel larger molecules such as trans-decalin fit in thiourea adduct channel.)... 

Epipolasin-B (61), mp 92 °C, was one of two isothiocyanates obtained from the sponge Epipolasis kushimotogensis. Neither the isonitrile nor formamido analog were found with the isothiocyanate. Instead, the thiourea adduct of /J-phenylethylamine was isolated along with another isothiocyanate-thiourea pair [51]. The absolute configuration of 61 was determined by appropriate... 

Electron donation by potential carcinogens, such as 2-acetylaminodi-benzothiophene, has been estimated from the strength of their charge-transfer complexes with chloranil in acetonitrile. - In this context it should be noted that the hydrogen bonding of phenol to the 77-electrons of dibenzothiophene has been studied and that a thiourea adduct has proved useful in the removal of dibenzothiophene from oil. - ... 

Further routes of cyclizations have been studied in parallel in the case of cis- and rra/J5-2-hydroxymethyl-l-cyclohexylamine (106) (880PP73). The preparation of thiourea or urea adducts 107 and 108 with phenyl isothiocyanate or phenyl isocyanate proceeds smoothly. The reaction of 107 with methyl iodide and subsequent alkali treatment, by elimination of methyl mercaptan, resulted in the iminooxazine 109 in high yields. The ring closures of both cis and trans thiourea adducts to 1,3-oxazines proceed with retention. Cyclodesulfuration of the adduct 107 by mercury(II) oxide or N,N -dicyclohexylcarbodiimide resulted in the iminooxazine 109, but the yield was low and the purification of the product was cumbersome. The ring closure of 108 with thionyl chloride led to the iminooxazine 109 in only moderate yield. 

The sulfide fraction of non-biodegraded petroleums usually contains a complement of n-alkyl substituted sulfides, thiolanes and thianes, in addition to the terpenoid class. In the biodegraded Alberta oil sand bitumens, however, n-alkyl substituted sulfides are absent. The two classes of sulfides can be separated by thiourea adduction, the n-alkyl-containing molecules being adducted. Raney nickel reduction of the Bellshill Lake sulfides (1 11 yielded a series of n-alkanes showing a distribution quite similar to that of the n-alkanes in the saturate fraction of this oil. In some oils the thiolane and thiane concentrations are commensurate, e.g. Houmann, Figure 13 in others, the concentration of thianes may be small compared to thiolanes. 

Structural investigations showed that the tellurium in tellurium bis[thiosulfonates] is bonded to two sulfur atoms with an S —Te —S angle of approximately 100°4-6. In the bis[thiourea] adducts of these compounds, tellurium is in the center of a /raw.v-square planar arrangement of sulfur atoms7 u. 

Divinyl tellurium treated with a solution of thiourea in 5 molar hydrochloric acid at 20° produced, after 6 h, tellurium, acetaldehyde, and the thiourea-adduct of tellurium(II) chloride10. 

Rubinstein 1. and Strausz O. P. (1979) Geochemistry of the thiourea adduct fraction from an Alberta petroleum. Geochim. Cosmochim. Acta 43, 1387-1392. 

Most of the complexes have well defined melting points. They appear to be monomeric in solution . An interesting method for the preparation of thiazolidine-2-thione complexes of aryl tellurium trichlorides is the addition of the tellurium compound to a melt of the ligand kept at 110°. Complexes with 1 1, 1 2, and 1 4 stoichiometries (Te-compound ligand) were obtained after recrystallization from dry methanol. Phenyl tellurium trichloride complexes with thiourea appear to form only when an organic solvent is used as the reaction medium in aqueous media the trichloride is reduced to the monochloride that is isolated as the thiourea adduct . 

Branched Alkanes. 2,6,10,14-Tetramethyl-hexadecane (phytane) and 2,6,10,14-tetramethyl-pentadecane (pristane) were found in considerable amounts (3). The dominance of phytane over pristane was observed. Other aliphatic isoprenoid alkanes C15 (2,6,10-trimethyl-dodecane, farnesane), C-, (2,6,10-trimethyl-tridecane), and C-g (2,6,10-trimethyl-pentaaecane) were also identified (4). In tne thiourea adduct of the branched-cyclic fraction, a homologous... 

An improvement in the synthesis of the chloride Bii2CI 4, based on crystallization from a reduced KCl-BiCU melt, has been reported, together with new X-ray diffraction data. Bismuth(iii) chloride forms a 1 1 adduct with SnCl2, ° and a structure determination for the thiourea adduct 3BiCl3,7SC(NH2)2 shows the presence of the dinuclear cation [Bi2Cl4(tu)6] and the anion [BiCl5(tu)] all bismuth atoms are in octahedral co-ordination.Stability constants for all... 

R. W. Schiessler and D. Flitter, Urea and Thiourea Adduction of C5-C42-Hydro-carbons, Journal of the American Chemical Society 74 1720-1723 (1952). 

Separation and Sub-fractionation of Alkanes Saturated hydrocarbons were separated from the neutral oil by silica-gel (60-120 mesh, dehydrated at 150°C for 5 h) chromatography in a 1 m X 30 mm i.d. column eluted with distilled n-hexane. n-Alkanes were separated from iso-octane solutions of total alkanes by adsorption for one week on 5 X molecular sieve (freshly dehydrated for 2h h at U00°C). Washing with iso-octane, followed by Soxhlet extraction, freed the molecular sieve from inwanted non-adsorbed compo mds n-alkanes were recovered by desorption after refluxing the molecular sieve for several hours with n-hexane. For the Kuwait crude and fluidized-bed tar, the molecular-sieve treatment was preceded by urea-adduction of n-alkanes and thiourea-adduction of branched-chain alkanes. 

Fukushima, K. Far-infrared spectra and structure of monochlorocyclohexane in a thiourea adduct. J. Mol. Struct. 1976. 34. 67. 

An allyl-type radical is also obtained by irradiation of thiourea adduct of cycloheptane, o-values also presented for 4-methyl cyclohexenyl. 

The separation of n-alkanes by clathration techniques is well documented. Methods such as urea and thiourea adduction as well as molecular sieves have been employed ... 

Figures 18 and 19 demonstrate that the separation of n-alkanes from a complex mixture is more clean-cut than their differentiation by thiourea adduction.

FIGURE 19. Gas-liquid chromatograms of (a) thiourea adduct and (b) a non-adduct portion of branched-cyclic hydrocarbon fraction from Green River shale. Conditions 1.5 m x 2 mm column 4% JXR on Chromosorb G. Programmed 100-300 °C, ca 5° min 62.64 Reproduced by permission of Springer-Verlag... 

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