Indan special

Benzocyclobutenes form a special class of cyclobutenes because the double bond is part of an aromatic ring. Perfluoro(3-alkyl-l,2-benzocyclobutenes) rearrange in the presence of anti-mony(V) fluoride to indanes via styrene intermediates.27-31 Thus, perfluorobenzocyclobutenes 34 give perfluoroindanes 35 in moderate yields.27... 

Returning now to the discussion of other carbocyclic species, we will consider the process involving 1-indanone and other keto derivatives of indane. We expect no special stabilization or destabilization over that of indane - none of these species may be expected to be aromatic or antiaromatic save that of the benzene ring therein. Starting with 1-indanone itself (X = CO, Y = Z = CH2) ... 

This reaction is essentially thermoneutral. Although we lack enthalpy of formation data for the corresponding 1,3-benzodithiole, the weakness of 1,3 sulfur-sulfur interactions as manifest by the near equality [52] of the enthalpies of formation of 1,3- and 1,4-dithiane (unlike 1,3- and 1,4-dioxane) suggests no special interaction in this nonaromatic heterocycle. Said differently, the thermoneutrality of the above reaction, as opposed to profound exothermicity (21 kJ mol ) for indane (six n electrons) and the endothermicity (29 kJ mol1) for benzimidazolinone (ten n electrons), suggests phenylene trithiocarbonate (ten n electrons) has an intermediate degree of aromaticity. For the latter two species, analysis of the related reactions ... 

The best-known are General Electric Ultem poly (ether imides) these offer heat deflection temperatures of 207 to 221°C and continuous service temperatures of 170 to 180°C. Also popular are Amoco Torlon polyamide-imides, with heat deflection temperatures of 278 to 282°C. More specialized are Ciba-Geigy trimethyl phenyl indane polyimides, with heat deflection temperatures of 232 to 257°C, embrittlement times of >2000 hr at 200°C... 

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