Weakly held protons

Robinson s theory was one of electron displacements propagated by electrostatic induction along the length of a carbon chain. As a hydrogen atom at one end of a carbon chain becomes a weakly held proton, electron charge drifts... 

The positive charge on the resulting metal ion is due to the atom possessing more nuclear protons than orbital electrons. The valence electrons are most distant from the nucleus thus, they are weakly held by the electrostatic attraction of the protons and, consequently, are easily stripped from atoms of the metals. 

Methyl acetate synthesis rate does not depend on DME pressure, but increases linearly with CO pressure up to 10 atm. This kinetic response is consistent with a sequence of elementary steps (Fig. 6) involving the formation of surface methyl groups at Brpnsted acid sites initially via direct DME reactions with protons and then via chain transfer reactions (propagation steps) of DME with surface acetyls formed via rate-determining CO insertion into C-0 bonds in methyl groups at the catal3rtic steady state (92). CO insertion occurs from the gas phase or via weakly held CO species adsorbed noncompetitively with CH3 groups. 

For a rigidly held, three-spin system, or when existing internal motion is very slow compared to the overall molecular tumbling, all relaxation methods appear to be adequate for structure determination, provided that the following assumptions are valid (a) relaxation occurs mainly through intramolecular, dipolar interactions between protons (b) the motion is isotropic and (c) differences in the relaxation rates between lines of a multiplet are negligibly small, that is, spins are weakly coupled. This simple case is demonstrated in Table V, which gives the calculated interproton distances for the bicycloheptanol derivative (52) of which H-1, -2, and -3 represent a typical example of a weakly coupled, isolated three-spin... 

Alternatively, some conclusions can be derived from the relative reactivities of car-banions. For example, DePuy and colleagues13 made use of a clever method involving reactions of silanes with hydroxide ion to deduce acidities of such weak acids as alkanes and ethylene. The silane reacts with hydroxide ion to form a pentacoordinate anion that ejects a carbanion held as a complex with the hydroxysilane rapid proton transfer gives the stable silanoxide ion and the carbon acid (equation 5). 

In 1925 physicists had known of two particles of matter, the proton and the electron. By 1947 five were known the proton, neutron, electron, muon, and neutrino. Yet another particle, the pion, was known, but it was associated with a force and it wasn t a component of matter. In 1925 they had known of two forces gravity and electromagnetism. Now there were four. The two new ones were the weak nuclear force (now called simply the weak force ) and a strong nuclear force that held nuclei together. 

Plywood and particle board are often glued with cheap, waterproof urea-formaldehyde resins. Two to three moles of formaldehyde are mixed with one mole of urea and a little ammonia as a basic catalyst. The reaction is allowed to proceed until the mixture becomes sympy, then it is applied to the wood surface. The wood surfaces are held together under heat and pressure, while polymerization continues and cross-linking takes place. Propose a mechanism for the base-catalyzed condensation of urea with formaldehyde to give a linear polymer, then show how further condensation leads to cross-linking. (Hint The carbonyl group lends acidity to the N—H protons of urea. A first condensation with formaldehyde leads to an inline, which is weakly electrophilic and reacts with another deprotonated urea.)... 

---