Heat conjugated

Enolate 120 can react with benzaldehyde to give the aldolate product 121 and hydrolysis gives the alcohol. In this case, diastereomers are formed, 122 and 123 and, at this point, we cannot predict one or the other as a major product. For the time being, we will assume that the reaction produces close to a 1 1 mixture of the two products. If this mixture is heated, conjugated ketone 124 is formed. The problem with this approach is clear when we recognize that enolate 120 can also react with unenolized 3-pentanone to produce the selfcondensation aldol product (125) and hydrolysis provides 126. Therefore, this reaction could produce three different aldol products. 

Conjugation of the newly formed double bond with the carbonyl group stabilizes the a p unsaturated aldehyde provides the driving force for the dehydration and controls Its regioselectivity Dehydration can be effected by heating the aldol with acid or base Normally if the a p unsaturated aldehyde is the desired product all that is done is to carry out the base catalyzed aldol addition reaction at elevated temperature Under these conditions once the aldol addition product is formed it rapidly loses water to form the a p unsaturated aldehyde... 

In disproportionation, rosin is heated over a catalyst to transfer hydrogen, yielding dehydro (5) and dihydro (8) resin acids. The dehydro acids are stabilized by the aromatic ring the dihydro acids contain only an isolated double bond in place of the less stable conjugated double bonds. 

Because of the aqueous solubiUty of polyelectrolyte precursor polymers, another method of polymer blend formation is possible. The precursor polymer is co-dissolved with a water-soluble matrix polymer, and films of the blend are cast. With heating, the fully conjugated conducting polymer is generated to form the composite film. This technique has been used for poly(arylene vinylenes) with a variety of water-soluble matrix polymers, including polyacrjiamide, poly(ethylene oxide), polyvinylpyrroHdinone, methylceUulose, and hydroxypropylceUulose (139—141). These blends generally exhibit phase-separated morphologies. 

On the other hand, not only initial colour but colour change (discolouration) of the resin under UV light and heat is important. Colour retention of a resin is related to the chemical stability and increases as the degree of non-aromatic conjugated unsaturation of the resin molecule decreases. Thus, for rosins a high level of abietic-type resin acids lead to relatively unstable resins. Hydrogenation and disproportionation as well as esterification provide improved stability and colour retention to rosins. 

Within such objects, conductive heat flow can be solved as well. This is sometimes called conjugate heat transfer in the literature. 

Selective hydroxylation with osmium tetroxide (one equivalent in ether-pyridine at 0 ) converts (27) to a solid mixture of stereoisomeric diols (28a) which can be converted to the corresponding secondary monotoluene-sulfonate (28b) by treatment with /7-toluenesulfonyl chloride in methylene dichloride-pyridine and then by pinacol rearrangement in tetrahydrofuran-lithium perchlorate -calcium carbonate into the unconjugated cyclohepte-none (29) in 41-48 % over-all yield from (27). Mild acid-catalyzed hydrolysis of the ketal-ketone (29) removes the ketal more drastic conditions by heating at 100° in 2 hydrochloric acid for 24 hr gives the conjugated diketone (30). 

We reach a similar conclusion when comparing benzene with the open-chain conjugated tr-iene (Z)-l,3,5-hexatriene. Here we compare two real molecules, both conjugated trienes, but one is cyclic and the other is not. The heat of hydrogenation of... 

This information coupled with the proposed mechanism of the Conrad-Limpach reaction, reasonably lead to the below proposed mechanisms. Conjugate addition of aniline and elimination of alcohol provides the P-anilinoacrylate 14, which upon heating to 180-320 °C gives species, like 34a,b, which undergo 6n-electrocyclization to 35 or 36, respectively. Loss of ethanol from 36 gives 35 and tautomerization provides 4-... 

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