- Synthesis and Characterization of a Series of Cholesterol-Based Liquid Crystalline Dimers with a Chiral (-)- Menthyl Terminal Group
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A novel series of cholesterol-based liquid crystalline (LC) dimers with a menthyl terminal group in the biphenyl base side have been synthesized. The chemical structures and LC properties of this series of compounds are characterized by FT-IR, 1H-NMR, elemental analysis, hot-stage coupled polarizing microscopy and differential scanning calorimetry. All the dimers exhibit enantiotropic mesophases. These dimesogenic compounds with a short spacer are chiral nematic LCs, while with long spacers, they are SmA and chiral nematic LCs. Some of these LC dimers exhibit iridescent colors in their chial nematic (N) states.
- Wu, Changcheng
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- Photoredox Activation of Formate Salts: Hydrocarboxylation of Alkenes via Carboxyl Group Transfer
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A photoredox activation mode of formate salts for carboxylation was developed. Using a formate salt as the reductant, carbonyl source, and hydrogen atom transfer reagent, a wide range of alkenes can be converted into acid products via a carboxyl group tra
- Huang, Yan,Hou, Jing,Zhan, Le-Wu,Zhang, Qian,Tang, Wan-Ying,Li, Bin-Dong
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p. 15004 - 15012
(2021/12/14)
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- The effect of the position of chiral (?)-menthyl on the formation of blue phase and mesophase behavior in biphenyl-benzoate liquid crystals
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Eight new chiral liquid crystal compounds 4-(4-menthyloxy-n-oxoalkanoyloxy) biphenyl-4′-yl 4-butoxybenzoates MnB4OB (n = 1–8), were prepared by modifying the position of chiral (?)-menthyl in the menthol based liquid crystal compounds through gradually increasing the alkyl chain length of the dicarboxylic spacer. All compounds were characterized by FT-IR and NMR spectroscopy in order to prove their chemical structures. Differential scanning calorimetry (DSC), polarized optical microscopy (POM) and X-ray diffraction were carried out to systematically investigate their phase transition behaviors. The position of chiral (?)-menthyl in relation to the core has a great effect on the formation of BPs and mesomorphic behaviors. Only CLCs M1B4OB and M2B4OB with short spacer chains presented blue phases. Furthermore, the length and parity of the flexible spacers have a profound influence on phase structures and phase transition behaviors. An odd-even effect is observed for these chiral liquid crystal compounds.
- Chen, Zhang-Pei,Wang, Xin-Jiao,Meng, Ling-Xin,Wang, Ji-Wei,Jia, Ying-Gang
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- Production of l-menthyl acetate through kinetic resolution by?Candida cylindracea lipase: effects of alkaloids as additives
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Abstract: Enzymatic transesterification of dl-menthol with vinyl acetate in tert-Butyl methyl ether (TBME) catalyzed by Candida cylindracea lipase (CCL) was carried out in the presence of cinchona alkaloid as additive. The effects of various reaction parameters, such as lipase nature and loading, acylating agent, molecular sieves, solvents and various additives, on the reactivity as well as on the enantioselectivity were investigated. A significant improvement of CCL reactivity has been recorded after using cinchona alkaloid as additive in TBME. A high enantiomeric ratio (E = 80) was achieved when 30?mol% of quinidine was added, and l-(-)-menthyl acetate was obtained with 93% optical purity and 49% conversion. This process was easily applied to gram-scale quantities, using commercially inexpensive lipase, providing high yield optically active menthol under mild experimental conditions. Graphical abstract: [Figure not available: see fulltext.].
- Belkacemi, Fatima Zohra,Merabet-Khelassi, Mounia,Aribi-Zouioueche, Louisa,Riant, Olivier
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p. 6847 - 6860
(2018/07/15)
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- COOLING SENSATION AGENT COMPOSITION, SENSORY STIMULATION AGENT COMPOSITION AND USE OF THE SAME
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Disclosed is a cooling sensation agent composition or sensory stimulation agent composition which contains at least one of diester compounds of dicarboxylic acid represented by the formula (1) wherein A represents CH2 or CH═CH, n represents an integer of 0 to 4 when A is CH2, or 1 when A is CH═CH, B is an alcohol residue having 10 to 18 carbon atoms and containing a para-menthane skeleton, which may have a substituent, and C is an alcohol residue having 6 to 18 carbon atoms, which may have a substituent as well as a flavor or fragrance composition, a beverage, a food product, a perfume or cosmetic product, a toiletry product, daily utensil products or groceries, a fiber, a fiber product, clothes, clothing or a medicine, wherein the cooling sensation agent composition or the sensory stimulation agent composition is compounded.
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Page/Page column 10
(2011/04/24)
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- Flavorant ester salts of polycarboxylic acids and methods for immobilizing and delivering flavorants containing hydroxyl groups
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Compositions are provided which contain immobilized flavorants for flavor delivery. In particular, smoking compositions are provided which contain flavorant ester salts of polycarboxylic acids.
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- Process for making monomenthyl esters
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A process for making monomenthyl esters of dicarboxylic acids is disclosed. Menthol reacts with a saturated, cyclic anhydride in the presence of a base catalyst under conditions effective to produce a mixture of mono- and bis-menthyl esters in which the molar ratio of mono- to bis-menthyl esters is enhanced compared with the ratio of esters produced in a similar uncatalyzed process.
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Page/Page column 5-6
(2008/06/13)
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- Fragrance release from the surface of branched poly(amide)s
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Enzymes are powerful tools in organic synthesis that are able to catalyse a wide variety of selective chemical transformations under mild and environmentally friendly conditions. Enzymes such as the lipases have also found applications in the synthesis and degradation of polymeric materials. However, the use of these natural catalysts in the synthesis and the post-synthetic modification of dendrimers and hyperbranched molecules is an application of chemistry yet to be explored extensively. In this study the use of two hydrolytic enzymes, a lipase from Candida cylindracea and a cutinase from Fusarium solani pisii, were investigated in the selective cleavage of ester groups situated on the peripheral layer of two families of branched polyamides. These branched polyamides were conjugated to simple fragrances citronellol and L-menthol via ester linkages. Hydrolysis of the ester linkage between the fragrances and the branched polyamide support was carried out in aqueous buffered systems at slightly basic pH values under the optimum operative conditions for the enzymes used. These preliminary qualitative investigations revealed that partial cleavage of the ester functionalities from the branched polyamide support had occurred. However, the ability of the enzymes to interact with the substrates decreased considerably as the branching density, the rigidity of the structure and the bulkiness of the polyamide-fragrance conjugates increased.
- Aulenta, Francesca,Drew, Michael G.B.,Foster, Alison,Hayes, Wayne,Rannard, Steven,Thornthwaite, David W.,Youngs, Tristan G.A.
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