Methoxy groups, randomization

The repeatedly noted ring-opening of ionized cyclopropane derivatives (Section III.A) seems also to account for the randomization of methoxy groups in ionized dimethyl 2-methoxy-3,3-dimethylcyclopropane-l,l-dicarboxylate. Similarly, the electron impact and chemical ionization mass spectra of benzoylcyclopropanes can be interpreted by ring-opening followed by facile 1,2-hydrogen migration, which precede the main dissociations... 

Chemical Structure and Properties. Homopolymer consists exclusively of repeating oxymethylene units. The copolymer contains alkyhdene units (eg, ethyUdene —CH2—CH2—) randomly distributed along the chain. A variety of end groups may be present in the polymers. Both homopolymer and copolymer may have alkoxy, especially methoxy (CH3 O—), or formate (HCOO—) end groups. Copolymer made with ethylene oxide has 2-hydroxyethoxy end groups. Homopolymer generally has acetate end groups. 

Reliable evidence of hydride anion transfer also comes from the polymerization of 1,3,5-tri-oxane. Here, analytical studies have shown that polytrioxane contains approximately the same number of formyloxy and methoxy end groups " . Transacetalization (cf. Sect. 5.3) that accompanies polymerization ensures a random distribution of these end groups in the polymer molecules. Formation of these end groups from a polymer chain proceeds as follows ... 

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