Cyclic and linear

Y. Wang and K. Kuczera. Molecular dynamics simulations of cyclic and linear DPDPE Influence of the disulfide bond on peptide fiexibility. J. Phys. Chem., 100 2555-2563, 1996. 

Molecular construction for a protein chain is just about impossible using the Z-matrix (unless you are particularly good at crossword puzzles). As 1 mentioned in Chapter 10, there are also immense practical difficulties associated with symmetric, cyclic and linear structures, and as time went by people began to question the use of the Z-matrix. 

Detailed reviews of the chemistry of Hexamine and its nitrolysis to RDX, HMX and other related cyclic and linear polynitramines, including discussions of various postulated reaction mechanisms, are given by Smolin and Rapoport (Ref 9) and by Wright (Ref 15), Methods for the prepn of RDX are also described in Encycl 3, C611 to C615... 

Diederich F, Gobbi L (1999) Cyclic and Linear Acetylenic Molecular Scaffolding. 201 43-79... 

Acetylene- and Diacetylene-Expanded Cycloalkanes and Rotanes. 201 1 - 42 Diederich F, Gobbi L (1999) Cyclic and Linear Acetylenic Molecular Scaffolding. 20J 43 - 79 Gobbi L, see Diederich F (1999) 201 43 -129... 

The traditional and most extensively used method of synthesis of chlorocyclophosphazenes [NPCl2] involves the reaction of finely ground ammonium chloride with phosphorus pentachloride in a high boiling solvent such as sym-tetrachloroethane. This reaction affords a mixture of cyclic and linear products from which the individual products have to be separated, usually by fractional distillation in high vacuum (1, 5,17,18,35-39), (Eq. 1) ... 

Summary Many cyclic and linear transition metal-silicon compounds have been obtained by the elimination of alkali halides. The structures of these complexes were determined by INEPT and INEPT-INADEQUATE NMR spectroscopy. 

It is well known that silicones can be prepared from dihalogenosilanes that undergo hydrolysis to generate disilanol. These latter intermediates produce cyclic or linear dialkylsiloxanes. The cyclic dialkylsiloxanes can be separated and ringopening polymerized whereas the linear ones can be condensed to yield silicones. However, it is still difficult to purify cyclic and linear precursors. Thus, in order to avoid cyclization, our objective concerned the polycondensation of fluorohybrid silanes. 

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