.


:




:

































 

 

 

 





252. . , (. 1). .

:

, , . The possibility of isolating the compound radicals of organic chemistry in an unpolymerized form was therefore generally abandoned during the period in which structural organic chemistry was advancing most rapidly.

, . A knowledge of the shape of the molecules is also necessary.

. Various admixtures have been identified.

(4) CH2CHXR, (5). If reaction (4) takes place, or if the initiating radical has the structure CH2-CHXR, then the further growth process (5) will occur.

, , , . Reduction is usually carried out at room temperature or at the boiling-point of ether, but when a higher temperature is necessary tetrahydrofurane has sometimes been used in place of ether.


, 32 , , , : > > . The acid chloride prepared by reaction of 32 with oxalyl chloride could be treated as mentioned in an earlier paper, with dimethylcadmium or the sequence acid chloride > diazoketone > chloromethyl ketone > methyl ketone could be employed.

. No satisfactory explanation of this observation has yet been offered.

253. . : . , .

:

. This chapter describes the use of organometallic compounds.

. The Table lists the yields of dichloroalkanes produced.

1,4 1,2. The oxidation cannot, however, distinguish 1,4 from 1,2 bonds.

. This article concerns the synthesis of silanes.

. The open-pore theory holds that adsorption takes place normally in layers on the walls of the capillaries.

. The earlier processes for the partial hydrogenation of butynediol used catalysts.

, . . We have obtained solutions by two very different methods, which are reported in this and following paper. The present paper describes the simpler of the two methods.


. This paper presents a complete table of such values.

. The latter procedure divides the nitrogen into amino and non-amino nitrogen.

254. : to give rise to, t lead to, to result in, to deal with, to give, to form, to produce, to yield, to bring about . .

:

, ( .) CO2. The reaction also gives rise to acetic acid esters such as ethylacetate and some combustion products of butane up to CO and CO2.

. The same method led to derivatives of a new condensed system.

, . It was found that other derivatives did not result in higher yields.

- . This decade has brought about a number of investigations of the physical-chemical characteristics of isoxazole derivatives.

. The treatment of this compound with sulphuric acid did not give any change in the colouring.

- , , , , , , , . Oxidation of liquified n-butane results in acetic acid, methylethyl ketone, ethyl acetate and, in a lower yield, diacetyl, acetone, acetaldehyde, formic acid, methyl and ethyl alcohols.

, . This section will briefly deal with new data concerning a more particular problem, that of homolytic halogenation of the side chain.

255. .


- , (. 201, 183).

:

. obtain a single compound involves its separation from the other amines formed.

. convert most salt forms of strongly basic anion exchangers to the free-base form requires a large excess of caustic alkali.

. Doubling the pressure cuts the fermentation time by one-third.

, . Treating ephedrine with cold sulfuric acid forms the ester of pseudoephedrine, inversion occurring.

. Carrying out this reaction was hindered by the presence of admixtures.

0,94 , . Stopping the reaction after absorption of 0.94 mol of hydrogen gave a mixture from which an acidic and a neutral fraction were isolated.

256. there.

( , , . .) , there.

:

, , , , , , .

In aqueous solution, there is present at a high, approximately constant concentration a substance, water, which is capable of acting both as an acid and a base.

14 . There are fourteen space-lattice types.

. There is much evidence for this viewpoint.

, .


Judging from later work by other investigators there was undoubtedly some methyl ethyl ketal present in the dimethyl.

25 11,4% 6,1% . At 25 there is present 11.4% of the hydroxybutyraldehyde in the equilibrium mixture as compared to 6.1% of the hydroxyvaleraldehyde.

He , . There can be no question that the reactivity of functional groups diminishes with the size of molecules.

, , . There are a great many isomeric compounds and, therefore, many isomerisation reactions.

, -, , . Even after distillation there appeared to be a trace of an impurity in the xylene which coloured alumina pale yellow.

, , ω-. From diamino acids, diabasic monoamino acids, and cyclic ammo acids, there may be formed by bacterial action compounds which have been termed ω-amino acids.

, , , , . It cannot be said that this mechanism has been disproved, but there is a considerable body of evidence which suggest that the main reaction is nuclear attack of the phenoxide ion by carbon dioxide.

- ; , . The reactions of benzyl and cinnamyl chlorides are similar; here the reactants are also mesomeric, but there is nevertheless an increase in activation energy during reaction.

, , -, , . The catalytic effect of heavy-metal acetylides on the methine hydrogen is not limited to acetylene alone, but is apparently general for many types of substituted acetylenes so long as there is an available acetylenic hydrogen.

, . There is particular reason why this should be so.


-, , . 1, . There appear to be no exceptions in the data in Table 1.

. there () + , : there + to be + + .

:

. There is a further point to be made here.

SN1 . With SN1 reactions there are also opposing factors to be considered.

. There is much to be said in favour of making provision for an inert atmosphere at all stages of work with reactive organometallic compounds. 2 : 475 600 mμ. In the ferric spectra there are two bands to be considered at 475 and 600 mμ.

257. .

, (. 133-142).

:

. We are faced with the problem of finding a structure for these hydroxides.

, . Since conductivity is little influenced by the surface conditions of a metal, it will not be discussed in further detail here.

. This critical temperature is actually influenced by pH and a series of other factors.

, , , . That selenium exerts only a weak dehydrogenating action is also indicated by the fact that cyclohexan rings containing tertially bound groups are not always capable of being aromatised.


, , . It must be remembered, however, that the intensity pattern may be influenced by the presence of other methyl groups elsewhere in the molecule, which will contribute their own specific absorption in this region.

. This paper was followed shortly by another by the same author.

. The reaction is followed by temperature rise.

. The condensation is followed by a rapid epoxide formation.

, . The bottom of the tube was heated to whiteness, and the acid acted upon by the heated potassium.

. and, or, but to be (. 118).

258. .

, , , - , . (. . 1718).

:

, , . , 1 Hg. , , , . The only publication dealing with the kinetics of the anthracene oxidation is that of Mars and Van Krevelen. It was found that the reaction rate was essentially independent of the anthracene partial pressure at pressures above about 1 mm Hg. Mars and Van Krevelen concluded that the data could be explained by assuming that the oxidation takes place in two steps.

, , ....


, , , . :

. , ρ 0,91.

Cross and Fugassi have found large differences in the entropy as well as in the heat of activation. The value of ρ was found to be 0.91.

, pax . , 1960 .:

In earlier cyclisation studies(1), it was shown that certain ketonitriles, on refluxing with hydrobromic-acetic acid yielded 9-arylphenanthrenes.

, , . . , 1954 .

?

1 . , , , . , , , . : Assays were performed on group of 812 plants (Nicotiana glutinosa), distributing each of an equal number of samples (including at least one standard and often a solvent blank) over 10 equivalent half-leaves. It was indeed quite surprising to find that the reconstituted nucleoprotein preparations produced local lesions (from 2 to 30 per half leaf), when tested at 10100 g/ml., which were indistinguishable in appearance from those of JMU at 0,1 g/ml.

:

For the purpose of investigating the celebrated phenomena of colours a triangular glass prism was procured. After darkening the laboratory and making a small window the optimum quantity of

i S t u n k, W. Jr. The Elements of Stylo. Revised by E. B. White, N. Y., 1959; L. and M. F i s . Style Guide for Chemists. N. Y. London, 1960; D. H. M n z e 1 ot al. Writing a Technical Paper. N. Y. London, 1961.


light would be let in from solar sources, the prism was placed before the entrance for the purpose of reflecting the light to the wall on the opposite side. It was found initially that due to the vivid and intense colours which were produced by this equipment the over-all effect was very pleasing when viewed by the eye. , , , , (. ). , . (. ) -, , , , . , , 1672 ., . :

I procured a triangular glass prism, to try therewith the celebrated phenomena of colours. And for that purpose, have darkened my laboratory and made a small hole in my window shade, to let in a convenient quantity of the sun's light, I placed my prism at the entrance, that the light might be thereby refracted to the opposite wall. It was at first a very pleasing diversion to view the vivid and intense colours produced thereby.

, , , 1.

, , -, . . , , , .

, , . .

259. . , , ,

D. H. M e n z 1 et al. Op. cit., p. 76.


. , , , . . :

, . . , . . , . . , . . , .. , . . . . , . α,α,α, ω α, α, α-, , , .

, , , .

, , , ,

,

. -, .

The present Review is a brief account of investigations carried out by the authors during recent years in collaboration with Ye. J. Vasilieva, R. G. Petrova, V. N. Kost, Sh. A. Karapetyan, N. A. Semenov, A. B. Belyavsky, and T. A. Kost on reactions of polychlorhydrocarbons.

In these investigations we were chiefly concerned with the changes in α, αa, a, ω-tetrachloroalkanes and α, α, α- trichloroalkanes, which became readily available by the telomerisation of ethylene and carbon tetrachloride or ethylene and chloroform, a reaction due to Joyce, Hanford, and Harmon.

In a number of cases, we have investigated polyhalogenoderivatives obtained by adding carbon tetrachloride or halogeno derivatives to olefins and to vinyl ethers as well as by condensing halogeno-derivatives with halogeno-olefins in the presence of aluminium chloride.


Our aim has been to work out general methods of synthesis of various organic compounds, starting with those involving, for example, the following radicals:

The investigation also involved the examination of some rearrangements in the series of unsaturated polychlorohydrocarbons. In the course of our investigation we have synthesised a great number of substances 1.

, , , . :

Excellent recovery in terms of body weight and long-term survival is afforded to lethally irradiated mice by post-irradiation injection of isologous bone marrow.

, , , :

Lethal irradiated mice make an excellent-recovery in terms of body weight and long-term survival, if after irradiation they receive an injection of isologous bone marrow2.

. :

The discovery of properdin in normal human serum and the demonstration of its bactericidal activity in the presence of complement depended largely on the use of zymosan as an agent to which properdin could be adsorbed from serum and subsequently eluted. When removing properdin from serum by absorption with zymosan, particular attention was given to the temperature. To make serum nonbactericidal towards typical properdin-sensitive organisms by depletion of properdin, about 99 per cent of the properdin had to be removed. Empirically this was done by subjecting the once-absorbed serum to second absorption with fresh zymosan for 30 min at 37.

The demonstration of properdin in human serum and of its bactericidal action in the presence of complement depended largely on the use of zymosan. Properdin adsorbs on zymosan and can then

1 A. H. , P. X. , . . 3 . , ( ) , Quarterly Reviews, v. X, 3. London, 1956.

2 D. . M e n z 1 et al. Op. cit.


be eluted from it. During this reaction the temperature requires particular attention. To deprive serum of the bactericidal activity conferred by properdin we had to remove 99 per cent "of the properdin, by subjecting the once-absorbed serum to a second absorption with fresh zymosan for 30 minutes at 37

. . , , , , 2. Benzene is sulfonated readily, One can sulfonate benzene readily. , , , :

It will be seen from the tables. = The tables show. The rearrangement has been shown by X to take place with inversion = X established that the rearrangement takes place with inversion.

. .

260. : one, he, the author, the writer, the investigator. , 258, , , - one the author, the writer, the investigator, . :

, . Following up some earlier work the author has carried out an investigation on the morphology and crystal orientation of polymers.

, , , the present author (writer, investigator).

- one , .

:

. One proceeds from one matrix to the next>>.

, . As a result of considerations of structural organic

1 D. H. M e n z e 1 et al. Op. cit., p. 80.

2 L. and M. F i e s e r. Op. cit., p. 10.


chemistry one would expect to obtain important information regarding the compounds.

. One may be left with choice between different bond lengths.

, , , . As was true for the case of acid catalysis, the form of the rate law does not allow one to decide which of the two steps is the rate-determining one.

, . Thus in certain cases sedimentation velocity method enables one to obtain information on separate components.

: one he, - :

, , , , , . When one considers the number of species of animals, birds, microorganisms, he begins to wonder, perhaps, how there could be so many millions of different proteins.

261. ().

, . . , . , .

:

IX , .

// Table IX are presented typical data illustrating the influence of peroxides and antioxidants.

. Of great importance in organic chemistry are nucleophilic displacements on carbon.

, 1903 . Of outstanding brilliance was the work of Windaus on cholesterol dating from 1903.

,


3. Significant of the origin of dihydroisoandrosterone is the fact that it corresponds precisely with cholesterol in the location of the double bond and the configuration at C3.

, .

In neither case has further replacement of the halogens been reported, nor has attempted alcoholysis with sodium alkoxides yielded crystalline products.

2,2'- 6,6--.

Quite as interesting is a comparison of the racemization rates of various substituted amides of 2.2'- dimethoxy-6,6-dicarboxy diphenyl.

, . Also entirely unknown is the mechanism whereby certain hydrocarbons start normal cells on a career of malignancy.

... Among these alcohols are substances with the formulas....

3,5 - , . Similarly were obtained 3,5'-diisooxazolyl and polyisoxazolyls up to the linear octaisoxazolyls that have already the properties of polymeric compounds.

262. it is (was, were, will be)... that (which, who, whom) . . : ; ; . : , , , , , , , . (. 261), , : it is (was, were, will be)... that (which, who, whom). , .

18 . . 273


263. :

, . This time it is the front boundary that is self-diffusing and the rear boundary self-sharpening.

. It is this nonseparability of the individual electrons orbits which introduces the real complexity into this problem.

, , -I , , , . The hydroxyl group and not the hydrogen is to be regarded as occupying the I-position in the chain, and it is the bond linking group to carbon that is weakened by the presence of the adjacent double bond.

, .

It is this periodicity which causes the energy levels to group themselves into bands, within which the levels are very closely spaced.

, . It is the hydrogen atom and not the phenyl group which migrates.

; , .

Such trends are often overlooked; it is only rather careful work which brings out this concentration effect, if it exists.

, .

It was the study of another reaction in solution, which showed that the logarithm of the velocity coefficient varied linearly.

, .

It is very likely the precision of the latter relationship that is responsible for the fit to the Hammet plot.

, . It is this last-mentioned amount of charge which may be thought of as holding the molecule together.

264. :

C-V , , . It was not until fairly recently that much attention was directed to the


calculation of theoretical C-V curves for currents controlled both by the rate of the electrode reaction and by diffusion.

. It was not till Monday that they could proceed with scientific investigation.

, . It was not until we were through with our experiment that I left the laboratory.

, , . It is when we introduce into our formulae quantitative relationships that Lorentz invariance is demanded.

, 11. It is for this reason that the reduction procedures described in Chapter 11 are to be preferred.

, (16), . Immiscible solvents, however, are rare, and it is very few actual systems and over limited ranges that Nernst's law in the simple form of equation (16) is valid.

- . It was in the laboratory that these parts were found.

1. , just, only:

. It is only when large temperature changes are involved, that the relative values alter appreciably.

. And yet it is just such complex amino acids which form the reactive groups of proteins.

2. .

, . It is when news came (that) tension began to drop.

3. it is that (which, who), . : It is he who did it=he did it.

18* 275


4. it is... whose. :

- . It is these halides whose hydrolysis rates are most sensitive to the ionsolvating power of the medium. . It is only these compounds whose nitrates are catalyzed by nitrous acid.

265. . , III .

:

10 . Included in Table 10 are some data on the amount of water formed.

3,579 . 10 , -. Centered on this bar is 10 sec of 3.579 me sinewave phased to cyan.

. Tabulated below are the ratios of the solubilities of anthracene and picric acid.

. Included in this category are amino compounds.

266. .

: as + .

:

, . This program he has defined as helping the starving people.

, . The electronegativity of an element we shall consider to be the sum of the first ionisation potential and the electron affinity.

, , , . The extent of the slow uptake was found to be proportional to the square root of the time and this relationship Ward showed to be characteristic of diffusion or solution process.


267. - all each.

, - all each to be.

:

, . The jour hydroxyketones were all obtained in a pure condition, if in small yields.

12,5. The oxides all show a well defined weak band at 12.5.

. The three corresponding monosulfonic acids all gave the same trisulfonyl chloride when treated with chlorosulfonic acid.

, , , . One type of hyperfine structure in which the lines of a spectral series all have the same number of components, has been explained as due to the presence of two or more isotopes of the element.

(32) , . The terms in (32) are all peculiar halfbreeds of lengths and angles, and all have the same form.

, , , . The hydroxydes derived from primary, secondary and tertiary alkylamines are all quite weak bases.

. These sulphonated ligands each contain three different types of coordinating groups.

. The last two electrons each occupy one of orbitals and the ground state is a diradical.


-

268. . . , , , , . - . , . , , . , , . . , , . , . , , , (. . 30).

, .

269.

(QKf) 1.


'2 3, QKf , (t$) . -- .

Boiling Crisis In Tubes

For the design of water cooled intensively heated devices a good knowledge of burnout flux () is necessary.

A considerable quantity2 of experimental stuff:! has been accumulated in the Soviet Union to the present day which permits to have reliable data on qBo for water which is subcooled to the temperature of saturation (ts) in the region of pressures up to critical. There is much less experimental stuff for the steam water mixture and therefore it may be recommended to give indications only for several limited combinations of process parameters.

Boiling Crisis In Tubes

Due lo 4 the great importance of the critical heat flux (qso) in designing 5 water-cooled intensive heat exchangers a considerable body of experimental data has been obtained in the Soviet Union so as to estimate e qso of subcooled water up to the critical pressure. There being considerably less data for the steam-water mixture 7, the estimations are valid only over a limited range of parameters8.

1 , , Present Perfect (. 15). , , Present Perfect.

fei, 2 Quantity , amount, number a good (great) deal, much (many); a considerable body .

3 Experimental stuff , stuff .


뻗 , . . experimental data experimental evidence, experimental material (. 55).

4 D u e to , , owing to, because of (. . 2526).

5In designing , (. 104).

6So as to estimate so as to , to estimate (. 201), so as to . estimate , (. 240).

7 (. 197) there (. 256).

8 . be valid, over a range .

270.

, 1, 2, 2. 3 3 , . 5 6, , . . 17.

As a rule experimental data have been received in experiments with stainless steel tubes heated by direct or alternating current of low voltage. Experimental installations were constructed either in form of closed circulation circuit or following the principle of once through flow. In this case the steam from the supercritical boiler came to the stand where this steam was cooled and condensed in a heat exchanger while the medium with fixed enthalpy and pressure was remitted to the experimental tube. Fig. 1 show such an apparatus.


The data were essentially obtained on stainless steel tubes heated by direct or alternating low voltage current. The test apparatus involved either a closed circulation circuit or uniflow. In the latter case the supercritical boiler supplied overheated steam to the stand, the steam was cooled and condensed in a heat exchanger and the medium of a definite heat content and pressure was then fed into the test section (see Fig. 1).

1 receive data . , - . to obtain.

as a rule, essentially.

2 stainlesssteel tubes, low voltage current, electric (. 50).

3 apparatus. , (. 46).

4 the test apparatus involved. To involve (. 240).

5 , , . . , , , , in the latter case (. 64).

6 , , , (. 253). the steam, steam to the stand.

7 (see Fig. 1).

271.

1 2 , . .


3 - 3, 4 , i , .

5 , 6 , 7 , , , 8 , . 9 10 gltf.

The moment of crisis initiation was detected either visually by the reddening of the tube or by control instruments which indicate a sharp rise of the experimental tube wall temperature. The heat flux was determined by the voltage fall on the experimental section and by the electric current intensity in the tube.

Experimental data received by means of burnout heat flux at a forced water movement and steam water mixture flow in tubes are considered from the standpoint of view that the value of burnout heat flux is being determined as single valued factors: the pressure P, mass velocity Wa and working medium enthalpy in that seclion of the channel where the crisis originated.

An analysis of experimental data that are known at present shows however that in certain regions of pressures, heat contents and mass velocites of the medium the burnout heat flux value depends upon such factors as heat flux distribution along the channel perimeter and its length, geometrical sizes of the heated channel and the com pressibility of the medium filling the preswitched sections that are situated between the circulation initiator and the heated channel. Some data about the influence of these factors on <?BO are given in this paper. *-

The crisis was observed to start either by the reddening of the tube or with devices checking the sharp temperature increase of the tube wall. The heat flux was determined by the voltage drop and current intensity on the tube.

The treatment of experimental data for critical heat fluxes in tubes is often based on the assumption|that such fluxes can


bedetermined unequivocally from such variables as pressure (P), mass velocity (Wg) and heat content (z) in that cross-section of the channel where crisis originated. The available experimental evidence shows, however, that in a particular range of pressure, heat content, and mass velocity the initiation of the boiling crisis can also be markedly affected by such factors as the heat flux distribution around the channel perimeter and along its length, the geometrical dimensions of the channel heated and the compressibility of the medium in the section preceding the experimental one. This paper reports on the effect of these factors on

1 - (. 207).

2 , . . .

3 , (. 253).

4 single valued, a unequivocally. 6 experimental data, experimental evidence (. 55).

6 in certain regions, a in a particular range (. 78).

7 the initiati on of the crisis can be markedly affected by... (cm. 257).

8 . , , preswitched sections. , -, () on to switch (to turn) on, -, , , , , . . . the section preceding the experimental one ( one cm. 62).

9B , (. 253): this paper reports on....

10 effect on, upon.

272.

,


. 2 2 3, 4 , . 1 5, , 6 7 8 9 . , 10 12 13 (if) 100, . . 14 , = 100 , =400 /2 =0 15 4,10 /2 16 17 b (b =)

ib 18, . . 19 , , 20, 21 , i' 22 , . 23 0 1 , , ts < 0, > 1.





:


: 2015-10-27; !; : 361 |


:

:

, ,
==> ...

1626 - | 1619 -


© 2015-2024 lektsii.org - -

: 0.265 .