CH3OH tetramers

The vapor of CH3OH also contains some cyclic tetramer, (CH3OH)4,... 

As a vapog methanol exists to an extent as a tetramer, (CH30H)4, in which four CH3OH molecules are held together by hydrogen bonds. Propose a reasonable structure for this tetramer. 

Fig. 83. CrCl2(CH30) CH3OH. Experimental (open circles) and calculated reciprocal susceptibility l/y as function of temperature. Solid curve calculated for tetramer with the parameters JJk=-6K, Jg=-1K and j . =0K. Dashed curve calculated for tetramer with the parameters J /k = — 5 K, J /k = — 5 K and Jc/k = — 1 K. For 7, 7g, Jc see original paper [68D12].

With polycondensation polymerization, two monomers join to produce dimers, trimers, tetramers, and higher ohgomers and finally polymers, plus a by-product which is usually H2O. HCl, NaCl, CH3OH, and other byproducts can be formed instead of water. When a single monomer is used instead of two monomers, the reaction is self-polycondensation polymerization. Stoichiometry is monitored and controlled when two different monomers are polymerized, but stoichiometry is ensured with selfpolycondensation. Most engineering thermoplastics can be produced by polycondensation polymerization ABS, PET, PBT, polyamides (nylons), polycarbonate, PAI, LCP, TPI, PEI, PPS, PPE, PSU, and PAEK. 

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