Structural isomerization

Trialkyl esters of phosphonic acid exist ia two structurally isomeric forms. The trialkylphosphites, P(OR)2, are isomers of the more stable phosphonates, 0=PR(0R)2, and the former may be rearranged to resemble the latter with catalytic quantities of alkylating agent. The dialkyl alkylphosphonates are used as flame retardants, plasticizers, and iatermediates. The MichaeUs-Arbusov reaction may be used for a variety of compound types, including mono- and diphosphites having aryl as weU as alkyl substituents (22). Triaryl phosphites do not readily undergo the MichaeUs-Arbusov reaction, although there are a few special cases. 

Structural isomerization of three-membered rings with exocyclic unsaturation (Scheme 21) has been found with aziridineimines (Section 5.04.3.13) and diaziridineimines (Section 5.08.3.2.4). This involves an acyclic intermediate, while large ring systems prefer to isomerize through bicyclic ones. The 1,2- to 1,3-diazepine conversion is an example (Scheme 22) (Section 5.18.2.2). 

The interaction of l-methoxybut-l-en-3-yne with aromatic azides proceeds at the unsubstituted acetylenic bond to furnish two structural isomeric triazoles, 166 and 167 (4 1 ratio), due to the different 1,3-dipole orientations (83DIS). 

The following reactions share only the feature that they are structural isomerizations. They incorporate a variety of reagents and procedures from acid catalysts to photolysis. 

Linalol, CjoHjgO, is isomeric with geraniol and nerol, but it is structurally isomeric, and not stereoisomeric, as it is known in both optical forms. It was first isolated by Morin from oil of linaloe. The same body has been isolated from various other essential oils, an[Pg.114]

Kjj = number of structurally isomeric paraffins of molecular formula without asymmetric carbon atoms ... 

The number of structurally isomeric hydrocarbons with formula n 2n+2-2At o symptoticdlly proportional to p-" (3M-5)/2 paraffins p is equal to zero, that is, the number is asymptotically proportional to p. For m 1, the proportionality factor is 1/4. 

Structurally isomeric disubstituted paraffins. The number of structurally isomeric alcohols is, apparently, the same... 

Now we focus on the number of different structurally isomeric disubstituted paraffins of the form where X and Y are... 

It is the generating function of all structurally isomeric disubstituted paraffins C Hj XY. 

The tree can be constructed in five steps and, correspondingly, the generating function of the structurally isomeric molecules can be built up from five factors (multiplication of the generating function in the case of independence cf. Sec. 17). 

Summing (3.21) over w 3, 4, 5, we obtain the generating function of the structural isomeric cycloparaffins which we will denote by P. Summation over w 1, 2, 3,. .. is easier. Summation and recombination of the terms provide the following sequence of results ... 

Using the terminology of Sec. 5 of the Introduction we can state the number of those structurally isomeric homologues of a given basic compound which contain n carbon atoms more than the basic compound is asymptotically proportional to the number of the structurally isomeric The formula indicates, furthermore, how the... 

The curious combinatorial number p, that is, the number of the structurally isomeric paraffins CjjHjjj.j, which intrigued Cayley, is asymptotically given by (4.81). 

BlaC31 Blair, C. M., Henze, H. R. The number of structurally isomeric alcohols of the methanol series. J. Amer. Chem. Soc. 53 (1931) 3042-3046. 

TayW43 Taylor, W. J. Applications of Polya s Theorem to optical, geometrical and structural isomerism. J. Chem. Phys. 11 (1943) 532. 

Structural isomerism is common among all types of organic compounds. For example, there are... 

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