P-sinensal

Pyrethrum cinerariifolium (L.) Trev. P. sinense DC Chu Chong Jiu (flower) Essential oil, adenine, choline, stachydrine.49 Sedative, refrigerant in headache, influenza. 

Chrysanthemum cinerriaefolium C. jucundum, C. koraiense, C. morifolium, C. sinenseCitrus reticulata, Leonurus heterophyllus, L. japonicus, L. macranthus, L. mongolicus, L. pseudo-macranthus, Pyrethrum cinerariifolium, P. sinense, Solanum lyratum, S. melongena Stachys chinensis, S. baicalensis, S. japonica... 

Trans P-sinensal 441 is obtained from the aldehyde 438 prepared by selective ozonolysis of trans-famesene 437. Wittig olefmation of 438 with 1-formylethylidene-phosphorane 440 gives trans P-sinensal 441. Reaction of 438 with 1-ethoxycarbonyl-ethylidene-triphenylphosphorane 439 yields the ethyl ester 442, from which 441 can also be obtained 237 (Scheme 77). Furthermore, a working group of the BASF synthesized a-sinensal 443 and p-sinensal 441 using Wittig reactions 238). 

This regio- and stereoselective reaction was used to obtain the triunsaturated ester 1 in a short synthesis of the sesquiterpene p-sinensal (2). 

The stereoselective synthesis of p-sinensal (14) has been achieved by reaction of the T -allylnickel(n) complex (12) (derived from bromomyrcene) with the chloro-... 

This time vinyl Grignard was used for the vinyl anion and dehydration of (66) gave a mixture of (68) and (69). These were not separated as a mixture of a and p sinensals is acceptable as the product. 

In comparing the 12 aldehydes and their relative intensities shown in Table I, it is not surprising that seven of die 12 are found in both oils at essentially the same levels. However, the relative intensities of the other five are interesting in that three of the five differing aldehydes are totally absent in the other oil. For example, E-2-octenal (peak 14) was observed only in the Early-Mid season oil whereas Z-2-nonenal (peak 17) and p-sinensal (peak 28) were only found in the Valencia oil. Only two aldehydes, namely acetaldehyde (peak 1, with possible co-elution of ethyl propanoate) and nonanal (peak 13) had appreciable intensity differences. It is quite possible that the major aroma quality differences between these two oils is due to the marked differences in these five aldehydes. P-sinensal has long been considered a major quality factor in orange oils II) and the lack of this positive aroma component in the Early-Mid oil may explain in part the lower aroma quality of this oil. 

Composition The main component is (+)-limonene (see p-menthadienes) (usually >90%). The organoleptic properties are mainly due to components such as octanal, decanal (see alkanals), citral (all <0.5%), a-and p- sinensals as well as nootkatone (see ere-mophilanes) (all <0.05%). 

GC-0 methods are commonly classified in four categories dilution, time-intensity, detection frequency, and posterior intensity methods. Dilntion analysis, the most applied method, is based on successive dilutions of an aroma extract until no odor is perceived by the panelists. This procedure, usually performed by a reduced number of assessors is mainly represented by CHARM (combined hedonic aroma response method) [67], developed by Acree and coworkers, and AEDA (aroma extraction dilution analysis), first presented by Ullrich and Grosch [68]. The former method has been applied to the investigation of two sweet orange oils from different varieties, one Florida Valencia and the other Brazilian Pera [69]. The intensities and qualities of their odor-active components were assessed. CHARM results indicated for both the oils that the most odor-active compounds are associated with the polar fraction compounds straight chain aldehydes (Cg-C,4), p-sinensal, and linalool presented the major CHARM responses. On the other hand, AEDA has... 

The aldehydes a-sinensal and p-sinensal with a veiy low odor threshold occur as minor compounds in essential oils from various Citrus species. 

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