Cyclotene

To form a highly resistive interface between the ASIC surface and the fluidic system, a polymer layer of Cyclotene is deposited on the ASIC surface before fabrication of the polymeric micro fluidic system. Cyclotene has high electrical resistance and good chemical stability. The excellent transmission properties ranging... 

FIGURE 7.10 Structures of volatile compounds characterized from toasty caramel aroma released in wine from toasted woods during aging. (1) 3,5-dihydroxy-2-methyl-4H-pyran-4-one (2) 3-hydroxy-2-methyl-4H-pyran-4-one (3) 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP) (4) 4-hydroxy-2,5-dimethylfuran-3(2H)-one (furaneol) (5) 2,3-dihydro-5-hydroxy-6-methyl-4H-pyran-4-one (dihydromaltol) (6) 2-hydroxy-3-methyl-2-cyclopenten-l-one (or cyclotene) (Cutzach et al., 1997 ) (7) 3-hydroxy-4,5-dymethyl-2(5H)-furanone (Sotolon Camara et al., 2006a,b,c) (8) 2-furanmethanethiol (furfurylthiol Tominaga et al., 2000). 

An Isolation and concentration scheme should be appropriate for the sample under Investigation. As an example of this, a distillation technique would not be satisfactory for separating caramel aroma compounds such as Maltol, Cyclotene, or Furaneol which possess an enolone structure and do not steam distil. 

Furans are the most abundant products of the Maillard reaction and they account for the caramel-like odor of heated carbohydrates (8). Some sugar degradation compounds, such as maltol, isomaltol, 4-hydroxy-5-methyl-3(2H)-furanone, 2,5-dimethyl-4-hydroxy-3(2H)-furanone, and 2-hydroxy-3-methyl-2-cyclopentene-l-one (cyclotene), have odors usually described predominantly... 

The experiments have been completed by additional reaction of xylose, fructose and some characteristic sugar degradation products like cyclotene, Furaneol and diacetyl and by thermal decomposition of Ama-dori rearrangement products. It is well knwon that sugars can react with suitable amino compounds very easily. In the course of these reactions sugars are mostly decomposed and brown melanoidins are formed. By-products of these melanoidins are many volatile compounds of characteristic aroma properties. They are also responsible for the well known aromas of heated food like meat, coffee and bread. 

Ofcourse, the number of components increase with rising temperature. Examples are carbocyclic compounds. Most of them are cycloalkenones and hydroxycycloalkenones. One reason for this fact is their isomerization. As we could demonstrate (12) cyclotene forms at 180° C 3 isomeric compounds and additionally 3 methylcyclopentanones or-pen-tenones via elimination of one molecule of water (Figure 2). Hydroxy-cyclopentenones and-hexenonesare well known to be important aroma compounds in caramel flavours (13,14). 

Figure 2 Reaction of cyclotene with amino acids...

Cyclotene is the precursor of dihydrocyclopentapyrazines after having reacted with ammonia respectively amino acids to form cyclotene imine. Figure 2 demonstrates not only the isomerization and transformation of this compound but also the formula of bis-dihydro-cyclopentapyrazines as special reaction products. They are formed by condensation of cyclotene-imine and represent a mixture of 4 di-astereomeric compounds. These compounds produce identical mass spectra (Shibamoto et a 1,16). We have carried out corresponding experiments by heating Furaneol with phenylalanine or serine in an autoclave at 180 0 C. As Figure 3 demonstrates some monocyclic pyrazines are formed by reaction of the degradation products from Furaneol. 

In the cysteine/glucose model experiments glucose reduc-tone, acetylformoin, furaneol and cyclotene were detected as major constituents indicating that the 1-deoxy-osone route is operative at pH-values o 5 to 7. As main component we identified by MS, IR- and H-NMR-spectroscopy 4-hydroxy-2,5-dimethyl-3(2H)thiophenone. Obviously this compound is less reactive than the corresponding norfuraneol derivative. Thiofuraneol is also formed from glucose/reductone, acetylformoin and furaneol as demonstrated in model experiments. Surprisingly, it is not formed in cysteine/rhamnose experiments, where furaneol is a major compound. In addition 2-acetyl-4-thiolanone and 5-hydroxymethyl-2-methyl-3-thiolanone were identified for the first time as cysteine specific products. 

Walradt et al. (42) identified some 6,7-dihydro-5H-cyclopenta-pyrazines in roasted peanuts and presumed that cyclotene was the precursor. Tricyclic pyrazines are also formed by reacting cyclotene with alanine (43). 

The alicyclic ketones have been identified as being important flavor precursors by Flament et al. (15) and more recently by MacLeod and Ames (44), who identified a similar compound (3-methyl-cyclo-pentanone) in heated ground beef. Flament et al. (15) singled out the importance of these compounds, particularly in the presence of alhylpyrazines. Nishimura et al. (41) produced a meaty odor by heating 2-hydroxy-3-methylcyclopent-2-enone with cyclotene and HaS. Two volatile compounds described as having meaty odor were 2-methyl-cyclopentanone and 3-methylcyclopentanone. Thus, cyclotene appears to be a key precursor of "roast beef" flavor. 

Dark malt contains 10 mg kg 1 maltoxazine, as well as 15, 60, 3, and 3 mg kg of maltol, its dihydrohydroxy derivative, cyclotene, and HDMF, respectively.127 A model system of maltose-proline leads to 40 mg kg 1 sugar maltoxazine, whereas the model system of glucose-proline gives only slightly less. 

The effectiveness of various precursors of these compounds was investigated quantitatively by Ottinger and Hofmann.283 Hexose-derived cyclotene was the common precursor for both 33 and 35, as well as 34 and 36. The formation of each compound is very much determined by the nature of the N-containing precursor. Thus, for example, pyrrolidine (e.g., formed by thermal decarboxylation of proline) plus cyclotene produced 33 and 35 only, whereas 1-pyrroline (derived from proline... 

Some intermediates to fine chemicals are prepared industrially by vinylation of aromatics. We have selected three well-known products as representative cases, namely an intermediate to Naproxen, a non-steroidal antirheumatic drug (Albermarle) (Equation 11) an intermediate to Prosulfuron, a potent herbicide (Ciba Geigy-Novartis) (Equation 12) and a monomer for polymerization to Cyclotene electronic resins (Dow Chemicals) (Equation 13). 

The synthesis of the monomer for Cyclotene resins (Equation 13) is accompanied by the formation of by-products that derive from internal rather than terminal aryl attack on the vinyl group. Further decrease of selectivity is caused by aryl attack on only one of the terminal carbon atoms of the two siloxane vinyl groups and by hydrogenolysis at the C-Si bond carbons, followed by aryl group attack on the terminal or the internal carbon atom of the vinyl group thus formed. 

Tonari. K., Ichimoto, 1., Ueda, H., and Tat-sumi, C., Mannich reaction of cyclotene. Novel synthesis of 3,5-diniethyl-2-cyclo-penten-2-ol-1-one, Nippon Nogei Kagaku Kai.shi. 44. 55, 1970 Chem Ab.str., 72, 10010.5, 1970. 

Heating also produces a series of other substances as a result of Maillard reactions. These include cyclotene, maltol and its derivatives (hydroxymaltol, dihydro-maltol), 2,3-dihydro-5-hydroxy-2-methyl4(/7) pyranone (DHM) and its 5-hydroxy derivative (DDMP) and furaneol. The sensory impact of these components can play an important role in developing the toasted , burnt , or caramel aromas of some barrel-aged wines (Cutzach et al. 1997,1999). 

Octanoic acid Sweaty, penetrating Cyclotene Sweet, toasty, caramel... 

Stokich T, Fulks C, Bemius M, Burdeaux D, Garrou P, Heistand RH. Planarization with Cyclotene 3022 (BCB) polymer coatings. MRS Symposium Proceedings Vol. 308,1993. 

Cyclotene (2-hydroxy-3-methyl-cyclopentenone, 3) and maltol (3-hydroxy-2-methyl-pyranone, 4) were easily identified as being responsible for OZ 1 and 3, with burnt sugar and caramel characteristics. These compounds have been previously identified in toasted oak wood by (20,21). 

Detection thresholds (a = 50 %) in the model water-alcohol solution were 5 mg/1 and 2 mg/1 for maltol and cycloten respectively (Table IV). DDMP has a powerful burnt sugar aroma at the dry state or by sniffing the effluent of gas chromatography, but it is odorless in aqueous solutions as wine. We have still not been able to measure thresholds of other molecules DHM and furaneol could be some very interesting molecules. 

SYNS CORYLON CORYLONE CYCLOTEN FEMA No. 2700 MAPLE D CTONE 3-METHYL-CYCLOPENTANE-L2-DIONE METHYL CYCLO-... 

CYCLOSAN see xMCWOOO CYCLOSIA see CMS850 CYCLOSPORIN see CQHIOO CYCLOSPORIN A see CQHIOO CYCLOSPORINE see CQHIOO CYCLOSPORINE A see CQHIOO CYCLOSTIN see CQC650 CYCLOTEN see HMB500... 

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