Thiele’s theory

According to K. H. Meyer, this surprising reactivity—which is also encountered amongst the enols—is explained by the fact that the OH-group activates the double bond adjacent to it and the two neighbouring double bonds of the conjugated system (Thiele s theory) are also involved in this activation. Phenol, therefore, can yield 1 2- and 1 4-substitution products with bromine, addition reactions first taking place ... 

By means of such assumptions, Werner was able to account for certain previously unexplained phenomena, such as the formation of tetrahydro-terephthalic acid by reduction of A dihydroterephthalic acid. It must be admitted, however, that this so-called 1,4 addition to conjugated double bonds was later explained in a more satisfactory manner by Johannes Thiele s theory of partial valences. 

It follows from Thiele s theory that if six CH groups are arranged... 

Cyclooctatetraene (I) was first prepared in 1911 [1], Its properties came as a great surprise to most organic chemists at the time conditioned by the knowledge of the properties of a cyclic system of formally alternate single and double bonds as found in benzene, and by Thiele s theory of partial valencies, and notwithstanding Bamberger s concept of hexacentric systems,(see Chapter I), they had expected it to be like benzene in its properties. But like benzene it was not. 

A classic example is the dimerization of methyl cyclopentadienylcarboxylate (37) to Thiele s ester (38)67. Although diene 37b should be more reactive than 37c according to the FMO theory, it was diene 37c that reacted with diene 37b (equation 17). 

Geerke DP, Thiel S, Thiel W, van Gunsteren WF. J Chem Theory Comput 2007 3 1499-509. 

Senn HM, Thiel S, Thiel H (2005) Enzymatic hydroxylation in p-hydroxybenzoate hydroxylase a case study for QM/MM molecular dynamics. J. Chem. Theory Comput. 1 494-505... 

The formation of Thiele s ester 6.217 is a remarkable example of several of the kinds of selectivity that we have been seeing in the last few sections, all of which can be explained by frontier orbital theory. The particular pair of cyclopenta-dienes which do actually react together 6.215 and 6.216 are not the only ones present. As a result of the rapid 1,5-sigmatropic hydrogen shifts [see (Section 6.3.1.3) page 197], all three isomeric cyclopentadiene carboxylic esters are present, and any combination of these is in principle possible. As each pair can combine in several different ways there are, in fact, 72 possible Diels-Alder adducts. 

The anomalous behaviour of butadiene on halogenation has been recognized for some time. It would be expected that the addition of bromine across one of the double bonds would produce only the molecule CH2BrCHBr CH=CH2. However, in addition to the 1,2-dibromo, compound there is a considerable yield of the 1,4-dibromo compound CH2Br—CH=CH—CH2Br, which contains a double bond in the 2,3 position. In order to explain this behaviour, Thiele proposed a theory of partial valencies. In this theory the second link in a double bond does not fully neutralize the affinity of the two carbon atoms so that they are left with a residual affinity In a system of alternate double and single bonds, the residual affinities of the inner atoms combine across the single bonds whilst those of the outer atoms remain free to attract other atoms. Thiele s formula for butadiene was therefore... 

Reactivity of strongly bonded molecules was considered by Thiele [60], who introduced the concept of residual valence. This is tied in with Bayer s strain theory in the sense that a solution for the same question was sought. Whereas the stereochemistry of the cycloalkanes made Bayer s theory obsolete, the later introduction of resonance more or less confirmed Thiele s intuition. 

Early electronic formulations of benzene could not explain aromatic stability but did nevertheless produce new systematizations. The classical paper of Kermack and Robinson in which benzene was represented by the symbol (4), essentially a restatement of Thiele s structure, led Robinson i to the idea of the aromatic sextet. Electronic theory at the time recognized the importance of stable associations of electrons in pairs and in octets but provided no basis for the stability attributed to a group of six electrons. 

Thiel W 1996 Perspectives on semiempirical molecular orbital theory New Methods in Computationai Quantum Meohanios (Adv. Chem. Phys. XCiti) ed I Prigogine I and S A Rice (New York Wiley) pp 703-57 Earlier texts dealing with semi-empirical methods include ... 

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