Sorbic acid derivatives

Abscisin II is a plant hormone which accelerates (in interaction with other factors) the abscission of young fruit of cotton. It can accelerate leaf senescence and abscission, inhibit flowering, and induce dormancy. It has no activity as an auxin or a gibberellin but counteracts the action of these hormones. Abscisin II was isolated from the acid fraction of an acetone extract by chromatographic procedures guided by an abscission bioassay. Its structure was determined from elemental analysis, mass spectrum, and infrared, ultraviolet, and nuclear magnetic resonance spectra. Comparisons of these with relevant spectra of isophorone and sorbic acid derivatives confirmed that abscisin II is 3-methyl-5-(1-hydroxy-4-oxo-2, 6, 6-trimethyl-2-cyclohexen-l-yl)-c s, trans-2, 4-pen-tadienoic acid. This carbon skeleton is shown to be unique among the known sesquiterpenes. 

Later, Tieke reported the UV- and y-irradiation polymerization of butadiene derivatives crystallized in perovskite-type layer structures [21,22]. He reported the solid-state polymerization of butadienes containing aminomethyl groups as pendant substituents that form layered perovskite halide salts to yield erythro-diisotactic 1,4-trans polymers. Interestingly, Tieke and his coworker determined the crystal structure of the polymerized compounds of some derivatives by X-ray diffraction [23,24]. From comparative X-ray studies of monomeric and polymeric crystals, a contraction of the lattice constant parallel to the polymer chain direction by approximately 8% is evident. Both the carboxylic acid and aminomethyl substituent groups are in an isotactic arrangement, resulting in diisotactic polymer chains. He also referred to the y-radiation polymerization of molecular crystals of the sorbic acid derivatives with a long alkyl chain as the N-substituent [25]. More recently, Schlitter and Beck reported the solid-state polymerization of lithium sorbate [26]. However, the details of topochemical polymerization of 1,3-diene monomers were not revealed until very recently. 

Muconic and sorbic acid derivatives, independent of their EZ configurations, have similar molecular conformations in the crystalhne state. All the diene... 

Photoreactivitv. It is noticed from the Table that only the sorbic acid derivatives are reactive upon UV- and y-irradiation. From spectroscopic studies of the reaction products a 1,4-addition reaction of the unsaturated units is evident. For example, spectral changes of 1ft in the infrared are essentially identical wi those observed in layer perovskites (compare Figures 12 and 2). c-NHfi-spectra of U are also consistent with a 1,4-trans-adduct (Figure 13). Especially the signal of carbon atom (a) exhibits a splitting, which could indicate the presence of configurational isomers. Further studies are necessary to analyze the stereoregularity of the polymer of la. 

When hydrogen bonds can be formed between 2 and hydroxylic solvents such as CD3OD, the selectivity dropped considerably, as expected [119]. The [4 + 2] cycloaddition of 2 can also be highly diastereoselective with aliphatic dienes. With sorbic acid derivatives 194 having a removable chiral 2,2-dimethyl-oxazoline auxiliary, 195 was isolated with an almost perfect stereocontrol during the addition process (Scheme 51) [120],... 

An excess of crotonaldehyde or aUphatic, ahcyhc, and aromatic hydrocarbons and their derivatives is used as a solvent to produce compounds of molecular weights of 1000—5000 (25—28). After removal of unreacted components and solvent, the adduct referred to as polyester is decomposed in acidic media or by pyrolysis (29—36). Proper operation of acidic decomposition can give high yields of pure /n j ,/n7 j -2,4-hexadienoic acid, whereas the pyrolysis gives a mixture of isomers that must be converted to the pure trans,trans form. The thermal decomposition is carried out in the presence of alkaU or amine catalysts. A simultaneous codistillation of the sorbic acid as it forms and the component used as the solvent can simplify the process scheme. The catalyst remains in the reaction batch. Suitable solvents and entraining agents include most inert Hquids that bod at 200—300°C, eg, aUphatic hydrocarbons. When the polyester is spHt thermally at 170—180°C and the sorbic acid is distilled direcdy with the solvent, production and purification can be combined in a single step. The solvent can be reused after removal of the sorbic acid (34). The isomeric mixture can be converted to the thermodynamically more stable trans,trans form in the presence of iodine, alkaU, or sulfuric or hydrochloric acid (37,38). 

Gandini and Rieumont26,119 have carried out an extensive examination of the polymerizability of several vinyl esters of furan carboxylic acids and of the causes of the autoinhibition which most of them display with free-radical initiation. The compounds studied were the vinyl esters of 2-furoic, 2-furylacetic, 2-furylpropionic, 2-furylacrylic and sorbic acid. All these derivatives, showed the same strong indifference towards radical polymerization. Only when treated with large doses (10—30%) of initiator did they give small yields of oligomers. The structure of all these products was carefully studied by spectroscopic and other techniques. Invariably, it was... 

Examples of ditactic polydienes are provided by a class of crystalline polymers derived from the alkyl-esters of the trans-trans isomer of sorbic acid.101,102 For example trans-poly (methyl sorbate) (-CH(CH3)-CH =... 

Figure 1 summarizes the chemical structures of the topochemically polymerizable 1,3-diene monomers providing stereoregular 1,4-trans polymer (Scheme 6) [ 16]. Most of the polymerizable monomers contain benzyl, naphthylmethyl, and long alkyl-chain substituents in their chemical structures. The (ZyZ)-, (E,Z)-, and ( , )-muconic and sorbic acids as well as the other diene carboxylic acids are used as the ester, amide, and ammonium derivatives. In contrast to this, the carboxylic acids themselves have crystal structures unfavorable for polymerization while they undergo [2-1-2] photodimerization, as has already been described in the preceding sections.

DimethyloxazoUdine derivatives of sorbic acid, singlet oxygen cycloaddition, 260, 261... 

Pasteurized blended cheese =S43 >41 Cheese cream, anhydrous milk fat, dehydrated cream (in quantities such that the fat derived from them is less than 5% (w/w) in finished product) water salt food-grade colours, spices and flavours mould inhibitors (sorbic acid, potassium/sodium sorbate, and/or sodium/calcium propionates), at levels sgO.2% (w/w) finished product... 

Sorbic acid has also been shown to be a suitable probe for the analysis of the alkylphosphonic acids and their monoester derivatives (14). A run buffer consisting of 5 mM sorbic acid and 0.1 mM decamethonium bromide, adjusted to pH 6, was used to separate a mixture of eight alkyl alkylphospho-nates. The use of the EOF modifier decamethonium bromide reduced the EOF at pH 6 to enhance the resolution and gave complete separation of the alkylphosphonic acids and their monoester derivatives (e.g. MPA and IMPA) in less than 15 minutes, as shown in Figure 3. 

Benzoic acid and its derivatives are among the most widely used antimicrobial agents these, together with the propionates, sulfur dioxide, nitrates, nitrites and sorbic acid, account for the bulk of food preservatives. A number of other compounds find use, however, in various miscellaneous applications, including 3-acetyl-6-methyl-3//-pyran-2,4-dione (67)... 

Khandelwal, G.D. and Wedzicha, B.L., Derivatives of sorbic acid-thiol adducts, Food Chem., 37,159, 1990a. 

Derivative benzoates and parabenzoates have been used primarily in fruit juices, chocolate syrup, pie fillings, pickled vegetables, relishes, horseradish, and cheese (Barbosa-Canovas et al., 2003). Other foodstuffs where sodium benzoate is used include soft drinks, baked goods, and lollipops (Poulter, 2007). Benzaldehyde and benzoic alcohol are better known to be yeast inhibitors. Benzoic acid has been found to release fewer protons than sulphite, nitrite, or acetic acid and it may be speculated that benzoic acid is not a classic weak-acid preservative. However, due to a lower pKa value, benzoic acid releases three to four times more protons than sorbic acid. This is a sizable concentration of protons although not as much as other weak-acid preservatives (Stratford and Anslow, 1998). Inhibition of growth is strongly pH-dependent and most effective under acidic conditions. Under these conditions the protonated form of the acid is predominantly found (Visti, Viljakainen, and Laakso, 2003). Another unexpected discovery was that benzoic acid appears to be a pro-oxidant. This was unexpected as it is a well-known fact 2-hydroxybenzoic acid (or salicylic acid) acts as a scavenger of free radicals in vivo (Piper, 1999). 

Lewis acid catalyzed versions of [4 4- 2] cycloadditions are restricted to functionalized dieno-philes. Nonfunetionalized alkenes and alkynes cannot be activated with Lewis acids and in thermal [4 + 2] cycloadditions these suhstrates usually show low reactivity. It has been reported that intcrmolecular cycloaddition of unactivated alkynes to dienes can be accelerated with low-va-lent titanium, iron or rhodium catalysts via metal-mediated - -complex formation and subsequent reductive elimination39 44. Usually, however, low product selectivities are observed due to side reactions, such as aromatization, isomerization or oligomerization. More effective are nickel-catalyzed intramolecular [4 4- 2]-dienyne cycloadditions which were developed for the synthesis of polycycles containing 1.4-cyclohexadienes45. Thus, treatment of dienyne 1, derived from sorbic acid, with 10mol% of Ni(cod)2 and 30 mol % of tris(o-biphenyl) phosphite in tetrahydrofuran at room temperature affords bicyclic 1,4-dienes 2, via intramolecular [4 + 2] cycloaddition, with excellent yield and moderate to complete diastereocontrol by substituents attached to the substrate. The reaction is sensitive towards variation in the catalyst and the ligand. 

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