Aliphatic cycle

On the basis of the analyses carried out it can be maintained that the presence of branching or an aliphatic cycle increases AIT. The analysis does not allow differentiation between the effects of branching or cyclization. The AIT averages of the linear, branched and cyclic compounds are respectively 364 10°C, 437 17 C and424 irc. 

The nature of the products formed is rather unusual. The formation of aniline implies a reaction between the ketone and ammonia to yield the cyclohexanonei-mine. The latter then rearranges with aromatization, to yield aniline. Aromatiza-tion occurs with cyclohexanone, leading to the formation of phenol. Therefore, the formation of the aromatic ring is quicker than the opening of the aliphatic cycle. 

The mass spectra of sulfonamides, whose amido nitrogen pertains to an aliphatic cycle, have been investigated both in the El70,71,75 76 and ci77 modes. 

C. Aubert, J.-P. B gu and D. Bonnet-Delpon A Route to Aliphatic Cycles Bearing a CF3 Group ... 

Another type of epoxy oligomers are the cyclo-aliphatic ones, obtained by oxidation of cyclic diolefins with various peroxidic compounds (organic or inorganic hydroperoxides), hypochlorous acid, halogenhydrines and their derivatives, and oxygen or ozone. At present, the main industrial procedure for their production uses peracetic acid. In keeping with initial cycloolefin structure, diepoxides with different structures are produced, with the peculiarity that peroxidic oxygen is bound to the aliphatic cycle. 

The above-postulated overall mechanism considers two alternative pathways depending on the nature of the acetylene derivative. Region A outlines a proposal in which the formation of the a-complex intermediate is supported by the fact that the treatment of aliphatic terminal acetylenes with FeCl3 led to 2-chloro-l-alkenes or methyl ketones (Scheme 12). The catalytic cycle outlined in region B invoked the formation of the oxetene. Any attempt to control the final balance of the obtained... 

Interest in the possible persistence of aliphatic sulfides has arisen since they are produced in marine anaerobic sediments, and dimethylsulfide may be implicated in climate alteration (Charlson et al. 1987). Dimethylsnlfoniopropionate is produced by marine algae as an osmolyte, and has aronsed attention for several reasons. It can be the source of climatically active dimethylsulfide (Yoch 2002), so the role of specific bacteria has been considered in limiting its flux from the ocean and deflecting the prodncts of its transformation into the microbial sulfur cycle (Howard et al. 2006). 

Biodegradation of the aliphatic polyesters occurs by bulk erosion. The lactide/gly-colide polymer chains are cleaved by random nonenzymatic hydrolysis to the monomeric lactic and glycolic acids and are eliminated from the body through the Krebs cycle, primarily as carbon dioxide and in urine. 

Figure 6 Effect of alkyl-chain length of aliphatic acid cadmium salts monolayers, [CH3(CH2) .2COO-]2 Cd, on the amount of incorporated water (W2) and the evaporation speed of the water (v). The broken line is calculated from eq. (3). (surface pressure 30 mN m-i, dipping speed 100 mm min-1, 20 °C, at the 5th dipping cycle).

More recently, Kobayashi and co-workers reported on Zr-catalyzed additions of ketene and thioketene acetals to a range of aromatic and aliphatic aldehydes (Scheme 6.25) [83], As in the Erker study, the presence of protic additives proved critical here as well. As the example in Scheme 6.25 illustrates, the addition of larger amounts of iPrOH improved the yield and ee it was reported that in the absence of the alcohol additive much lower yield and enantioselectivities" were attained. The proposed catalytic cycle, depicted in Scheme 6.25, provides a plausible rationale for the role of the additive Si transfer is facilitated by iPrOH to regenerate the chiral catalyst. Finally, it is worthy of mention... 

Our early reports of the I A reaction in [ZnCcP, Cc] complexes were interpreted within the context of the simple ET cycle. Scheme I [8b, c]. As noted above, there are two limiting cases for this scheme, i) The I A reaction is slow I(t) appears with the triplet decay rate constant kp and disappears with the thermal ET rate constant k. ii) It is rapid here I(t) appears with k and disappears with kp. We reported that ZnCcP complexes with heterologous Cc s [8d] and with aliphatic Phe-82 mutants of yeast Cc [8b] fell into the former class, while the intermediate for fungal Cc appears rapidly [8d]. 

Huang L, Sturchio NC, Abrajano T, Heraty LJ, Holt BD (1999) Carbon and chlorine isotope fractionation of chlorinated aliphatic hydrocarbons by evaporation. Org Geochem 30(8A) 777-785 Jambon A, Deruelle B, Dreibus G, Pineau F (1995) Chlorine and bromine abundance in MORB the contrasting behavior of the Mid-Atlantic Ridge and East Pacific Rise and implications for chlorine geodynamic cycle. Chem Geol 126 101-117... 

This initial attack of the ozone molecule leads first to the formation of ortho- and para-hydroxylated by-products. These hydroxylated compounds are highly susceptible to further ozonation. The compounds lead to the formation of quinoid and, due to the opening of the aromatic cycle, to the formation of aliphatic products with carbonyl and carboxyl functions. The nucleophilic reaction is found locally on molecular sites showing an electronic deficit and, more frequently, on carbons carrying electron acceptor groups. In summary, the molecular ozone reactions are extremely selective and limited to unsaturated aromatic and aliphatic compounds as well as to specific functional groups. 

On the other hand, the method of Mukaiyama can be succesfully applied to silyl enol ethers of acetic and propionic acid derivatives. For example, perfect stereochemical control is attained in the reaction of silyl enol ether of 5-ethyl propanethioate with several aldehydes including aromatic, aliphatic and a,j5-unsaturated aldehydes, with syir.anti ratios of 100 0 and an ee >98%, provided that a polar solvent, such as propionitrile, and the "slow addition procedure " are used. Thus, a typical experimental procedure is as follows [32e] to a solution of tin(II) triflate (0.08 mmol, 20 mol%) in propionitrile (1 ml) was added (5)-l-methyl-2-[(iV-l-naphthylamino)methyl]pyrrolidine (97b. 0.088 mmol) in propionitrile (1 ml). The mixture was cooled at -78 °C, then a mixture of silyl enol ether of 5-ethyl propanethioate (99, 0.44 mmol) and an aldehyde (0.4 mmol) was slowly added to this solution over a period of 3 h, and the mixture stirred for a further 2 h. After work-up the aldol adduct was isolated as the corresponding trimethylsilyl ether. Most probably the catalytic cycle is that shown in Scheme 9.30. 

The best performing coatings were the vinyl ester, the bisphenol A epoxy cured with an aliphatic amine, and a novolac epoxy cured with a mixed aromatic/cycl oal i phati c amine. The saturated polyester, and a bisphenol A epoxy cured with a polyamide amine showed significant deterioration of the coating material in the acid, and corrosion of the underlying steel. Two types of novolac epoxies cured with aromatic amines showed intermediate performance. 

The current working model for the beneficial role of protic and halide additives in reactions with aliphatic amines is outlined in Scheme 9.10 [11]. In these reactions, the rhodium dihalide dimer 30 is proposed to enter two different catalytic cycles. In the productive catalytic cycle, the dimer is cleaved by solvation or binding with the substrate to give 31. Oxidative insertion followed by pro to nation of the rhodium alkoxide... 

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