香茅醇的合成研究

用硼氢化钾与丙二酸生成的丙二酰氧基硼氢化钾在四氢呋喃中与二氢月桂烯反应制备香茅醇。在60℃下，反应6h时，反应100％发生在末端双键，且有90％以上的硼原子加成在末端双键的1位碳原子上。然后加入氢氧化钾溶液和用质量分数为30％双氧水继续反应，得到质量分数大于90％的香茅醇，在该条件下没有发现酮生成。     

外消旋玫瑰醚合成的研究

该文报导以天然香茅醇为原料,采用光敏氧化法合成外消旋玫瑰醚。通过的氧化还、还原、环化三个单元的影响因素的探讨,筛选出合理的工艺条件,产品纯度〉９８％;茯理化指标,香气均达到国外同类产品的水平。     

甲氧基香茅醛合成方法的改进

以香茅醇为起始原料,经过醚化和氧化反应,简便地合成了甲氧基香茅醛,各步产物均经IR、MS和1HNMR图谱分析确证。该合成工艺与1998年文献[1]所采用的方法相比,以氢型强酸性阳离子交换树脂代替浓硫酸作为醚化反应的催化剂,以安全高效的三氧化铬吡啶盐酸盐(Corey试剂)代替三氧化铬二吡啶(Collins试剂)作为氧化剂,总收率由30%提高到了56 8%,减少了反应溶剂用量,简化了后处理操作,使生产成本降低,安全、对环境友好。     

Benzoyl peroxide–p‐acetylbenzylidenetriphenyl arsoniumylide initiated copolymerization of citronellol and styrene

Alternating copolymers, containing styrene and citronellol sequences, have been synthesized by radical polymerization using benzoylperoxide (BPO)–p‐acetylbenzylidenetriphenyl arsoniumylide (pABTAY) as initiator, in xylene at 80 ± 1 °C for 3 h under inert atmosphere. The kinetic expression is R_p ∝ [BPO]^0.88 [citronellol]^0.68 [styrene]^0.56 with BPO and R_p ∝ [pABTAY]^0.27 [citronellol]^0.76 [styrene]^0.63 with pABTAY, ie the system follows non‐ideal kinetics in both cases, because of primary radical termination and degradative chain transfer reactions. The activation energy with BPO and pABTAY is 94 kJ mol^?1 and 134 kJ mol^?1, respectively. Different spectral techniques, such as IR, FTIR, ¹H NMR and ¹³C NMR, have been used to characterize the copolymer, demonstrating the presence of alcoholic and phenyl groups of citronellol and styrene. The alternating nature of the copolymer is shown by the product of reactivity ratios r₁ (Sty) = 0.81 and r₂ (Citro) = 0.015 using BPO and r₁ (Sty) = 0.37 and r₂ (Citro) = 0.01 using (pABTAY), which are calculated by the Finemann–Ross method. A mechanism of copolymerization is proposed. © 2001 Society of Chemical Industry     

含硫香料——硫代香茅醇、硫代芳樟醇的合成研究

对香茅醇转化为硫代香茅醇及芳樟醇转化为硫代芳樟醇的合成方法及影响因素进行了研究。产品在极低浓度时,硫代香茅醇具有酸杨梅、番石榴的香韵,硫代芳樟醇具有橙桔香韵。     

Neotropical ant gardens

In ant gardens of lowland Amazonia, parabiotic ant speciesCamponotus femoratus andCrematogaster cf.limata parabiotica cultivate a taxonomically diverse group of epiphytic plants, whose establishment is restricted to arboreal carton ant nests. Epiphyte seeds are collected by workers ofCa. femoratus, the larger of the two ants, and stored unharmed in brood chambers where they subsequently germinate. Although seeds of some ant-garden epiphytes bear nutritional rewards, previous studies have shown that these rewards are not sufficient to explain the pattern of ant attraction to seeds. Five aromatic compounds occur frequently in and on the seeds of most ant-garden epiphytes and may be chemical cues by which ants recognize propagules of their symbiotic plants. The most widely distributed of these is methyl 6-methylsalicylate [6-MMS]1, previously reported as a major mandibular gland product in relatedCamponotus species and present in trace quantities inCa. femoratus males. (–)-Citronellol6 (previously unreported inCamponotus) was the principal volatile constituent in extracts of male heads, and (–)-mellein7 was present in small quantities. Discovery of 6-MMS inside the mandibular glands of maleCa. femoratus (and its presence in analogous glands of related ants) offers preliminary support for Ule's (1906) hypothesis that seeds attract ants by mimicking ant brood. In addition, the likely fungistatic activity of seed compounds suggests that they could retard microbial pathogens of ants and plants in the organic detritus of nest gardens. While the presence of identical seed compounds in so many unrelated plant lineages might represent a remarkable case of convergent evolution, other interpretations are possible.     

Synthesis of geranyl and citronellyl esters of coconut oil fatty acids through alcoholysis by Rhizomucor miehei lipase catalysis

Synthesis of geranyl and citronellyl esters of mixed fatty acids has been investigated by alcoholysis of coconut oil (CNO) using Rhizomucor miehei lipase. CNO fatty acid esters of geraniol and citronellol have unique mild flavors that can be used in food materials. Both geraniolysis and citronellolysis of CNO produce flavor esters in good yield. Depending on substrate concentration the molar yield is more than 50%. The optimized reaction conditions were: pressure, atmospheric; temperature, 50°C; incubation period, 5 h; and Lipozyme, 10% (w/w).     

Thienyl analogues of acyclic monoterpene alcohols and their biological activity

BACKGROUND: Thienyl analogues of linalool, geraniol, nerol and citronellol were synthesised and their sensory and anti‐ microbial activities were investigated. RESULTS: The thienyl analogues of linalool, geraniol, nerol and citronellol, in which the isobutenyl moiety was replaced by a thiophene substituent, were synthesised from commercially available 2‐ and 3‐methylthiophenes and 2‐ and 3‐thiophenecarboxaldehydes. The olfactory properties of the new compounds were generally of the corresponding parent terpene type; however, their relative volatility determined by the headspace gas chromatography method was lower by a factor of 34–42 compared with the parent alcohols. Antimicrobial activity against Aspergillus niger and Penicillium expansum of some thienyl analogues of linalool was 1.5–3 times higher than that of linalool, with a minimum inhibitory concentration of 0.2–0.1 µL mL^?1. CONCLUSION: Replacement of the isobutenyl moiety in acyclic monoterpene alcohols by a thienyl substituent results in the formation of new terpene analogues, some of which are interesting for perfumery and cosmetology because of their odour quality, tenacity and antimicrobial action. Copyright © 2009 Society of Chemical Industry     

Selectivity aspects in the multi-phase hydrogenation of α,β-unsaturated aldehydes over supported noble metal catalysts: Part II

The hydrogenation of cinnamaldehyde to cinnamyl alcohol over a platinum on carbon catalyst could be intensified and made more selective in a two-phase system using toluene and aqueous alkaline solution. Enhancement in the selectivity with respect to citronellol was noticed in the two-phase hydrogenation of citronellal, while the reaction rate was marginally affected. Potassium hydroxide and sodium hydroxide were found to be efficient promoters.