Blend enantiomeric

McPheron LJ, Seybold SJ, Storer A], Wood DL, Ohtsuka T, Kubo I, Effects of enantiomeric blend of verbenone on response of Ipsparaconffisus to naturally produced aggregation pheromone in the laboratory,/ Ecol23 2825-2839, 1997. 

Field bioassays with adult cerambycid beedes, Neoclytus acuminatus acumi-natus (F.) (Coleoptera Cerambycidae), revealed that males produce a pheromone that attracts both sexes. Male extracts revealed a single major male-specific compound IS, 3>S )-hexanediol. Field trials showed that a racemic blend of IS, 3S) and 2R, 3i )-hexanediols attracted both sexes and that activity was similar to enantiomerically enriched IS, 3S) hexanediol (e.e. 80.2%). However, a blend of all four stereoisomers attracted only a few beetles. ... 

Certainly, most of the data given in Table 17.2 are not qualified as indicators in authenticity assessment of food flavour, owing to their low and non-characteristic enantiomeric distributions, which could be simulated easily by calculated blending of the (S)-enantiomer (from biotechnological origin) with the synthetic racemate. 

For hundreds of years the essential oil of lavender has been well appreciated for perfumery purposes [72]. Lavender oil is obtained by steam distillation from the fresh-flowering tops of Lavandula angustifolia Miller (Lavandula officinalis Chaix) [73]. It is a colourless or pale yellow, clear liquid, with a fresh, sweet, floral, herbaceous odour on a woody balsamic base [73, 74]. According to the European Pharmacopoeia, characteristic components of lavender oils are limonene, cineol, 3-octanone, camphor, linalool, linalyl acetate, terpinen-4-ol, lavandulyl acetate, lavandulol and a-terpineol. Adulterations commonly include blends of lavender oils with lavandin oil or spike oil, and the addition of synthetic linalool and linalyl acetate. In contrast, genuine lavender oils contain as main constituents (i )-linalyl acetate and (i )-linalool of high enantiomeric purity (Fig. 17.14). 

Szocs, G Otvos, I. and Sanders, C. (2001). Erannis tiliaria (Lepidoptera Geometridae) males attracted to enantiomerically identical pheromone blend of Erannis defoliaria. Can. Entomol., 133, 297-299. 

Only two types of polymers are considered here. These are isotactic poly(5-methyl-hexene-l) (P5MH1), with a non-chiral side chain (for the sake of comparison) and mainly isotactic poly(4-methyl-hexene-l) (P4MH1). The side chain of the latter polymer is chiral since the two substituents of the carbon in the p position are a methyl and an ethyl group. Polymers that are made only of the S or the R conformers - in other words the true chiral polymers (P(S)4MH1 and P(R)4MH1), the racemic copolymer of the (R) and (S) monomers (P(R, S)4MH1) and of course the racemic blend of the two enantiomeric polymers - are available. 

Preliminary results obtained with the racemic P(R,S)4MH1 (the random copolymer of the R and S enantiomeric monomers) and of the racemic blend of P(S)4MH1 and P(R)4MH1, indicate a more conventional crystallization behavior crystallization of the tetragonal form takes place in the upper Tc range ( 183 and % 191 °C, respectively), presumably because both left- and right-handed helices (or helical stretches) are available at that temperature, whereas melting occurs at 211 and 214 °C. 

Enantio-IRMS also offers a direct method to detect conclusively a blend of enantio-pure chiral flavour compounds with synthetic racemates. An origin-specific enantiomeric ratio may be imitated but not yet detectable, neither by enantioselective analysis nor by IRMS-measurements. However, in the case of enantio-IRMS a simulated origin-specific enantiomeric distribution is proved by different 5 C-levels of the detected enantiomers. 

In Fig. 6.46 the experiments to reveal the origin of linalool from a commercially available spike oil are compared [107]. While enantioselective analysis detects the R(80%) S(20%) enantiomeric ratio, indicating a blend with synthetic racemate, the amount of synthetic racemate caimot be calculated, owing to a conceivable partial racemization of linalool during the processing of Lavandula oils. By means of enantio-IRMS investigation the blend of linalool from different origin is proved [R(-26.1 S(-30.67 J], whereas simple IRMS-analysis [R-i-S(-27.07g )] even sim-... 

In order to determine the absolute configuration of C, we synthesized (3Z,6Z,95,10/O-9,10-epoxy-3,6-henicosadiene (91) and its enantiomer 91 employing the Sharpless asymmetric epoxidation as the key step.55,56 Asymmetric epoxidation of D afforded (2/ ,35)-E of 80.6% ee. This was converted to the corresponding 3,5-dinitrobenzoate F and recrystallized to give enantiomerically pure F. Further synthetic transformation converted F to (95,10/0-91. Bioassay of (95,10/0-91 proved it to be pheromonally active, while the enantiomer (9/ ,105)-91 was inactive. A blend of A, B and C (= 91), however, was pheromonally inactive when tested against H. cunea. Two additional components 92 and 93 were necessary for the pheromone action. In 1987 Dr. H. Arn in Switzerland asked me to synthesize these two compounds. We did this, and in 1989 Toth, Arn and their coworkers published the identification of 92 and 93. 

Tsuji, H. and Okumura, A. (2009) Stereocomplex formation between enantiomeric substituted polydactide)s blends of poly[(S)-2-hydroxybutyrate] and poly[(R)-2-hydroxybutyrate]. Macromolecules, 42, 7263-7266. 

Tsuji, H. and Ikada, Y. (1992) Stereocomplex formation between enantiomeric polyflactic add)s. 6. Binary blends from copolymers. Macromolecules, 25, 5719-5723. 

Tsuji, H. (2000) In vitro hydrolysis of blends from enantiomeric poly(lactide)s. 1. WeU-stereocomplexed blend and non-blended films. Polymer, 41, 3621-3630. 

Tsuji, H. (2002) Autocatalytic hydrolysis of amorphous-made polylactides effects of L-lactide content, tacticity, and enantiomeric polymer blending. Polymer, 43,1789-1796. 

Tsuji, H. and Fukui, I. (2003) Enhanced thermal stability of poly(lactide)s in the melt by enantiomeric polymer blending. Polymer, 44, 2891-2896. 

As mentioned, the enantiomeric purity of lactic acid polymers significantly affects their properties. Pure poly (D-lactide) and pure poly (L-lactide) are crystalline materials. Poly (L-lactide) typically has about 40% crystallinity. Poly (D,L-lactide) is totally amorphous. Copolymers of D-lactide or L-lactide with D,L-lactide may or may not be crystalline, depending on the amount of comonomer. Blends of poly (L-lactide) and poly (D-lactide) are reported to have better mechanical properties than either of the homopolymers alone. ... 

Adulteration is done by either turpentine oil or a and p pinene. Further, blending is done using 5 3 carene and cedrol from cedarwood Chinese type. AFNOR (1992) presents data in the standard NF T 75 -254. Using chiral GC as his method of analysis, Casabianca (1996) determined that the enantiomeric ratio of a-thujene in cypress oil was as follows ( / ) (+) a thujene (45%) (15) () a-thujene (55%). 

Although this oil should be produced solely from fruits, more often the whole aerial parts are used. Adulteration is done by synthetic anethole or from other sources like star anise oil. Blending is done too with star anise oil and limonene + 60°. Analysis is done by GC-MS or by multidimensional enantiomeric separation. According to Ravid (1992), the chiral ratio of (+)-fenchone is 100%-0%. 

ISO standard 3053 shows character and data for this oil. Pure oils possess as marker the compound nootkatone from traces up to 0.8%, depending on the fruit status. This compound is used for blending, together with n-octanal, w-nonanal, n-decanal, and synthetic citral. Adulteration is performed by orange terpenes and distilled grapefruit residues from expression and limonene—80°. Detection must be done exclusively by multidimensional enantiomeric separation. Dugo and Mondello (2011) published the following chiral data (/ ) (-)-a-pinene (0.3%-0.8%) (5)-(+)-a-pinene (99.2% 99.7%) (/ )-(+) P pinene (62.0% 76.8%) (5) ( ) p-pinene (23.2%-38.0%) (/ )-(+)-sabinene (98.4%-98.5%) (5)-(-)-sabinene (1.5%-1.6%) (5)-(-)-limonene (0.5%-0.6%) (/ )-(+)-limonene... 

Litsea cubeba oil. Lemon oil washed as residues from production of terpene-free oil is preferably used, as these contain still all components of the pure lemon oil. Also lemon terpenes and heads of distilled grapefruit oils could be found. Blending is done by using synthetic decanal, non-anal, octanal, and citronellal from Corymbia citriodora oil. Detection is made by GC-MS and mainly by multidimensional enantiomeric separation with various methods (see part of methods). Mondello (1998) reports some constituents with chiral ratios as follows (f )-(+)-p-pinene 6.3% (5) ( )-P"pinene 93.7% (f )-(+)-sabinene 14.9% (5)-(-)-sabinene 85.1% (5)-(-)-limonene 1.6% (K) (+)-limonene 98.4% (5)-(+)-terpinen-4-ol 24.7% (/ )-(-)-terpinen-4-ol 75.3% and (5)-( ) a terpineol 75.2% (R)-(+)-a-terpineol 75.2%. Further on, Dugo and Mondello (2011) gave the following data (/ )-(+)-a-pinene (25.5%-31.5%) (5)-(-)- -pinene (68.5%-74.5%) (15,4/ ) ( ) camphene (86.2%-92.4%) (l/ ,45)-(+)-camphene (7.6%-13.8%) (5)-(-)-p-pinene... 

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