Solid state photolysis

Table 4.24 summarises the main features of solid-state photolysis-GC for polymer/additive analysis. Photolytic degradation products obtained from PE/1 % DLTDP and PE/1 % DSTDP, PMMA/9 % DNP and PVC/19 % DOP were examined [189]. The method has found little follow-up. 

Kupfer, R., Poliks, M.D. and Brinker, U.H. (1994). Carbenes in constrained systems. 2. First carbene reactions within zeolites-solid state photolysis of adamantane-2-spiro-3 -diazirine. J. Am. Chem. Soc. 116, 7393-7398... 

Chiral induction to obtain the /J-lactam 169 by photolysis of the chiral crystal 168 in the solid state is possible (equation 112). 

Many reactions that proceed with elimination of a gas (N2, COz, etc.) and formation of radical-pair intermediates show considerable stereochemical differences in solution and in the crystal. Thus, solid-state photolysis of the diaza compound 176 yields, among other products, cis-1,2-diphenylcyclopentane, 177 no trans isomer, 178, has been detected. Irradiation of 176 in solution leads to mixtures in which the trans product 178 predominates (244). 

Fig. 2 X-ray crystal structure of salt 39 prior to (left) and following (right) photolysis in the solid state...

Table 5 Enantioselectivity in the solid-state photolysis of salts 41b ...

Table 6 Solid-state photolysis of chiral salts 45b ...

Irradiation of a benzene solution of 3a gave tricyclic thietane 4a in 83% yield (Scheme 5 and Table 4, entry 1). The sohd-state photolysis also gave racemic 4a in 81% yield when the reaction conversion was 80% (entry 2). The solid-state reaction proceeded even at -78 °C (entry 3). 

When thiocarbamate 3b was irradiated in a benzene solution, thiolactone 5b was isolated in 90% yield (entry 4). The solid-state photolysis also gave thiolactone 5b in 85% yield when the reaction conversion was 78% (entry 4). 

Scheffer et al. carried out photolyses of monothioimides in the solid state with a 450-W high-pressure mercury lamp. In a carefully controlled run, photolysis of monothioimides 14a-d in the solid state with rigorous exclusion of moisture led to no reaction [40,41]. When no special attempts were made to... 

Photolysis of cycloheptenecarbothioamide 24d in the solid state also gave the corresponding p-thiolactam in specific yield (entry 7). As the X-ray crystallographic analysis revealed, the crystal is racemic (Fig. 9), and the isolated p-thiolactam was obtained as racemate. 

When thioamides 24f-h were irradiated in benzene with a high-pressure mercury lamp, iV-isopropyl-P-thiolactam 26 and 1,3,5-dithiazine 28 were obtained (Scheme 15 and Table 10, entries 1,3, and 5). Considerably different photochemical behavior was observed between that in solution and in the solid state. Powdered thioamide 24f was irradiated in the solid state at 0 °C until 19% conversion, because the solid changed to amorphous at around 20% conversion. In this case, only dithiazine 28f was obtained as the sole photoproduct (entry 2). On the contrary, photolysis of 24g gave a new type of p-lactam 27g as a main product in 88% yield in addition to dithiazine 28g (12%) the P-lactam 26g was not detected at all (entry 4). Photochemical ( ,Z) isomerization of (Z)-24g was also observed in the early stage of the reaction, where the ratio of the photostationary state was ZIE=1.9. In the case of 24h, P-thiolactam 27h was ob-... 

Photolysis of the monoazido species [Mn L (acac)L]BPh4 (where L is 1,4,7-triazacyclononane, is its N-methylated derivative, and acac is pentane-2,4-dionate) in the solid state has been demonstrated to yield the six-coordinate nitrido species [Mn L(N)(acac)]BPh4. ... 

Racemizations in the crystalline state have a long history. It is known that L-a-amino acids slowly racemize in the solid state [62]. As this also happens in solid proteins the implications are manifold, not only in pure chemistry but also in biochemistry, nutrition, food technology, and geology. Therefore, techniques have been developed to determine the dl ratio of amino acids down to 0.1% and inversion rate constants have been determined under acid hydrolysis conditions [63]. One could think of very slow deamination and readdition of the amine or an enolization mechanism. However, such reactions can also be induced by photolysis or radiolysis from natural sources [64]. 

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