51. Alternative. , , . , , alternative , (). , , , (. . 27)
:
. No final decision between all these various alternatives is possible at present.
. A number of alternatives have been proposed.
. An alternative method of reduction is to use atomic hydrogen.
, . An alternative mode of stabilization, by negative substituents, is also possible.
, , . The distribution curve may be used to provide additional data to make a decision between alternative mechanisms.
52. Approach. , , , .
:
, , , . The statistical approach is more powerful than the kinetic approach because it gives numerical values for constants which cannot be evaluated by the kinetic method.
. In this approach rates of reactions are not measured.
, . Both of these approaches make it possible to measure the area which a chemisorbed molecule occupies on a metal surface.
53. Consideration. , , , . :
The ability of several alkyl groups to become attached to the same benzene ring is almost certainly accounted for by steric considerations)).
54. End. , , , to this end, with this end in view, toward this end, . :
. ((Toward this end methanol was administered.
. this end we investigated several compounds.
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55. Evidence. . . :
. The chemical and X-ray evidence supports a head-to-tail structure of the polymer.
. Further evidence concerning this electrode reaction will be presented in the next chapter.
, - . Several lines of evidence indicate that the chair-form is of lower energy.
, . According to the latest evidence the Beckmann rearrangement is analogous to the carbonium ion rearrangements.
, , , . It is known from spectroacopic evidence that light capable of effecting the halogenation can split halogen molecules into atoms.
56. Experience. , , , , . experience , , . :
, , . As experience has shown that the reliability of
this device involves attention to small points its construction will be discussed at some length.
. The preparation and conditioning of membranes are very much a matter of experience.
57. Instance. , . :
, . Ethyl cyanoacelate may be condensed with arylhydrazines in the presence of sodium alkoxides to give equally good yields in many instances.
. In some instances the two bands fall close together in the spectrum of materials.
. In this instance the ideal situation is based upon no mixing.
58. Procedure. , , . :
- . Study of possible spectrophotometric procedures for measurement of the reaction of p-mercuribenzoate with sulphydryl groups were initiated.
. A discussion of the experimental procedure for this type of system has been given elsewhere.
. They suggested a new procedure to obtain these valuable compounds.
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59. Technique. , , , , , . :
. The ordinary techniques of manipulating organic compounds.
- 50 A. Particles as small as 50 A in size may be identified by proper electron microscopic technique.
. All three techniques have been used in chromatography according to the object in view and the nature of the components.
. This simple technique is called elution analysis.
60. (to be) of + . , to be of importance, interest, value. to be , . :
. It is of interest to consider the possibility of a reduced potential energy function of diatomic molecules.
. The reaction of hydrogen with carbon to produce methane is not of great significance at the moment.
, . It should be emphasized that the double bonds in the benzene ring are of inert character.
of + to be . : of importance; of interest; of value; , of note; of principle; , of use; of great moment; , of concern; , , , , , of necessity.
61. whatever + . : + . :
, . Whatever its nature, the activity of methacrylate is readily destroyed by hydrogen atoms and iodine molecules.
, / . The real surface area of films is sometimes equal to their apparent area whatever the film weight.
