2.6.10.14- Tetramethyl-hexadecane

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... 

Isoalkanes are hydrocarbons containing branched carbon chains. They are also a major group of constituents of oil. Five most abundant and important oil isoprenoid compounds are farnesane (/-C15 2, 6, 10-trimethyl-dodecane), trimethyl-tridecane (i-Cig), norpristane (i-Cig 2, 6, 10-trimethyl-pentadecane), pristane (i-Cig 2, 6, 10, 14-tetramethyl-pentadecane) and phytane (i-C2o 2, 6, 10, 14-tetramethyl-hexadecane). 

Pristane (Pr 2,6,10,14-tetramethylpentadecane) and phytane (Ph 2,6,10,14-tetramethyl-hexadecane) are common biomarkers present in most petroleum and geological samples. The primary source of these isoprenoids is considered to be the phytyl side chain of chlorophyll pigments in photosynthetic organisms (Peters and Moldowan, 1993 Li et ai, 1995 Hunt, 1996), although other sources (e.g. Archaebacteria) have been proposed (Chappe et al, 1980 Illich, 1983 Goossens et al, 1984 Rowland, 1990). Possible pathways for the formation of these isoprenoids from chlorophylls were compiled by Didyk et al. (1978). 

Evidence for the biological origin of reduced carbon in sedimentary rocks comes from two sources. One is the existence of chemofossils, that is, characteristic remnants of biologically important compounds more resistant to chemical degradation than others. Notable examples are the isoprenoids pristane (2,4,6,10-tetramethyl pentadecane) and phytane (2,4,6,10-tetramethyl hexadecane), which arise from the decay of chlorophyll (Eglin-ton and Calvin, 1967 Didyk et al., 1978 McKirdy and Hahn, 1982 Hahn,... 

C20H18CI2 f 1,6-Di-o-chlorophenyl-3,4-dimethylhexatriene, 31B, 35 C20H1BCI2 f 1,6-Di-p-chlorophenyl-3,4-dimethylhexatriene, 31B, 35 C20H38CI4, 2,6,11,15-Tetrachloro-2,6,11,15-tetramethyl-hexadecane,... 

Isoprenoid Alkanes. Early work su ested (Nooner and Oro, 1967 Gelpi and Oro, 1970a) that nearly all carbonaceous chondrites contain the isoprenoid alkanes pristane and phytane (2-,6-,10-,14-tetramethyl-pentadecane and -hexadecane). These two hydrocarbons, which may formally be r arded as tetramers of isoprene, CHj C(CH3)CH CH2, serve as biological markers on Earth, being derived mainly... 

The isotopic analyses applied to the water samples derived from the Lippe river longitudinal profile comprised main contaminants as illustrated above and described intensively in chapter 3.1.1. In detail stable carbon isotope ratios of tri-n-butyl phosphate (TBP), tris(chloroethyl)phosphate (TCEP), 2,4,7,9-tetramethyl-5-decyne-4,7-diol (TPDB), di- -butylphthalate, bis(2-ethylhexyl)phthalate (DEHP), galaxolide, tonalide, and squalene were determined. Further on, the internal standard d34-hexadecane was analysed simultaneously. Noteworthy, several compounds presented were also determined in the Rhine river samples. All results are summarized in Figure 7. 

Dispiro-l,2,4,5-tetraoxanes (45 1-3) were prepared with the intact peroxide functional group and tested for antimalarial activity [51], Dispiro-1,2,4,5-tetraoxanes, 1(5), 10( )-dimethyl-7,8,15,16-tetraoxodispiro[5,2,5,2]hexadecane (45 3) was as active as artemisinin, both in vitro and in vivo. Based on the resistance index (IC50(W-2)/IC5o(D-6)), 2,4,1 l,13-tetramethyl-7,8,15,16 tetraoxodispiro[5,2,5,2]hexadecane... 

Individual saturated hydrocarbons including n-alkanes (w-Cg through M-C40) and selected isoprenoids pristane (2,6,10,14-tetramethyl-pentadecane) and phytane (2,6,10,14-tetra-methyl-hexadecane). In some cases, another three highly abundant isoprenoid compounds famesane (2,6,10-trimethyl-Ci2), 2,6,I0-trimethyI-Ci3, and norpristane (2,6,I0-trimethyI-Ci5) are also included ... 

Aza-epothilone 1 (( )-(25,95,7 0f ,77f ,745)-10,14-dihydroxy-9,l 1,13,13-tetramethyl-2-[2-(l,2-dimethyl-benzimidazol-5-yl]-12,16-dioxo-l-oxa-5-aza-cyclo-hexadecane-5-carboxylic acid tert-butylester) and its 7,8-dehydro analogue 2 are potent inhibitors of human cancer cell growth, and represent a structurally new class of natural product-derived microtubule-stabilizing agents. 

The stable free radical polymerization technique is characterized by the growing polymer chains that are reversibly capped by a stable free radical [e.g., 2,2-tetramethyl-l-piperidynyloxy nitroxide (TEMPO)]. For example, stable polystyrene dispersions were prepared by the stable free radical polymerization of styrene conducted in miniemulsion polymerization at 135 C [62]. Sodium dodecylbenzene sulfonate, hexadecane, and potassium persulfate/ TEMPO were used as the surfactant, costabihzer, and initiator system, respectively. Prodpran et al. [63] studied the styrene miniemulsion polymerization stabilized by Dowfax 8390 and hexadecane and initiated by benzoyl peroxide at 125 °C. A molar ratio of TEMPO to benzoyl peroxide equal to 3 to 1 resulted in polystyrene with the lowest polydispersity index (1.3) of polymer molecular weight distribution. 

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