Bond, Link

In most covalent compounds, the strong covalent bonds link the atoms together into molecules, but the molecules themselves are held together by much weaker forces, hence the low melting points of molecular crystals and their inability to conduct electricity. These weak intermolecular forces are called van der WaaFs forces in general, they increase with increase in size of the molecule. Only... 

Left bond linked to the N bearing R right linked to the N bearing R,. 

Left bond linked to 4-C right bond linked to 5-C. 

Fig. 3. Sodium dodecyl sulfate—polyacrylamide gel electrophoretic pattern for molecular weight standards (lane 1) water-extractable proteins of defatted soybean meal (lane 2) purified IIS (glycinin) (lane 3) and purified 7S (P-conglycinin) (lane 4) where the numbers represent mol wt x 10. The gel was mn in the presence of 2-mercaptoethanol, resulting in the cleavage of the disulfide bond linking the acidic (A bands) and basic (B bands) polypeptides of the...

The long-range coupling of 2.2 Hz which appears in A and B, two quaternary C atoms in the NMR spectrum with appropriate shifts (5c = 76.6 and 83.0) and the two double-bond equivalents (molecular formula C TZ/oO) suggest that a CC triple bond links the two structural fragments. Hence the compound is identified as hex-3-yn-l-ol (C) in accordance with the coupling patterns. 

Fig. 3. The regular structure of a procyanidin-type condensed tannin showing characteristic 4,8 interflavonoid bonds linking the flavonoid units.

Hydrolysis of geminal fluorides requires activation by per- or polyfluoroalkyl or perfluoroaryl groups and by double bonds linked to the same or adjacent carbon The activation is the result of reducing the electron density at the fluorinated carbon, facilitating attack by, primarily, nucleophilic reagents... 

The most important aspect of Table 27.1 is that the 20 anino acids that occur in proteins share the common feature of being a-anino acids, and the differences fflnong them are in their side chains. Peptide bonds linking carboxyl and a-anino groups characterize the structure of proteins, but it is the side chains that are mainly responsible for theh properties. The side chains of the 20 commonly occuning amino acids encompass both large and small differences. The major differences between amino acid side chains concern ... 

FIGURE 2.3 The fluid network of H bonds linking water molecnles in the liqnid state. It is revealing to note that, in 10 psec, a photon of light (which travels at 3 X 10 m/sec) would move a distance of only 0.003 m. 

FIGURE 11.10 /3-Glycosidic bonds link nitrogenons bases and sngars to form nncleo-sides. 

When an amine reacts with an acid chloride, an amide is formed. What would happen, though, if a diamine and a diacid chloride were allowed to react Each partner could form two amide bonds, linking more and more molecules together until a giant polyamide resulted. In the same way, reaction of a diol with a diacid would lead to a polyester. 

Finally, although ultimately successful, the glycosidation studies on amphotericin B (1) reemphasize the difficulties encountered in this important area of synthesis. Of course, the /J-glycosidic bond linking the aglycon with the mycosamine, in combination with the... 

It was anticipated that fragments 147 and 214 could be united through an amide bond linking the nitrogen atom of the latter with C-8 of the former. Indeed, the active ester formed by treatment of carboxylic acid 147 with 1,3-diisopropylcarbodiimide and 1-hydro-xybenzotriazole reacts efficiently with amine 214 to afford dihydroxy amide 215 in 95 % yield. This convergent union creates a molecule that possesses all but two carbon atoms of the natural product. 

The differences between these structures result first from the intericosahedral B—B bonds linking the chains (e.g., the bridges involving isolated B5 atoms in MgAlB 4 or Mg2B,4 and B5 and B6 atoms in Na,Bo,gBj4), and second from the positions of the metal atoms and their occupancy. Metal atoms occupy interstitial... 

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