NOTES
Nov., 1938
FD
0.0 9.61 25.18 26.40 28.4 48.4 51.45 52.42 54.69 56.60 77.1 77.49 78.49 87.99 92.61 93.0 96.00 96.51 97.0 97.87 98.67 100
suMbfA.pY OF CWXLATED -5M x lo6HAC EXPtl.8 Calcd.
1.84
2813
TABLE 11 V S c T USING EQUATION "(6)AND OF EXPERIMENTAL DATA -KM
(1.84)
x losCalcd.
Exptl.1
6.09
X8.09)
2.66 2.36 1.94
1.36
x
-KM
EB
Exptl.'
10"-
H?Q
4.60
-KM
x
10-
Calcd.
Exptl.8"HAC
Calcd.
(2.66)
1.73
(1.73)
1.81
1.37
1.23
1.05
1.352 1 088 3.56 3.55
1.30 0.988
3.41
.756
2.61
0.895
0.827
3.18
.722
.700
0 741
0.889 2.23 .622 .608 ( .6W
2.03 .575 1.99
( ,555)
( ,555)
(1.95)
(1.95)
.657 ( ,639)
( .639)
(0.631)
( .631)
The KM values, calculated from the revised ketone (ClaHlsOa)was described. This has now equation (6),are now in very good agreement with been identified (by direct synthesis and mixed the experimental results. These are summarized melting point determination) as a-ethoxypropioin Table I1 and plotted in Figs. 1, 2, and 3. The veratrone predicted slope for chloroacetic acid is given in H~CO-~COCH(OGH~)CH~ Fig. 4; no experimental data for comparison are / available. The value oh K D for salicylic acid is OCHs extrapolated with equation (6) from the average The synthesis (after numerous unsuccessful a. d. 12%, at F D = 91.7, attempts, and using a variety of methods) was valueHM = 0.24 X a. d. accomplished as follows: and from the average KH = 0.98 X 2% determined by Korman and La Mer.' Veratrole pmpionyl chloride -+ Propioveratrone + The K D thus calculated is 0.21 X 10-3 a-Brompropioveratrone -+ Acetate of a-hydroxypropioveratrone which also has not yet been determined / \ experimentally. a-Hydroxypropioveratrone + a-Ethoxypropioveratrone The synthetic compound melted at 81-82'; It is apparent that true values of hydrogen and deuterium ion concentrations are obtainable from a mixed melting point with natural compound kinetic data when tested by means of acid dissocia- gave no depression. The melting point of the tion constants. 2,4-dinitrophenylhydrazone of the natural (6) (AC&C acid) Chitturn and La Mer, T=m JWWAL, 6% 2524 compound is 134-136'; synthetic compound, (1937). the mixed melting point also showed 134-136' ; (7) (Benzoic acid and hydroquinone) Rule and La Mer, ibid., 60, 1974 (1938). no depression.
+
( 8 ) (Chlokaeetic acid) Lewis and Sch&z, ibid., 06, 1918 (1834).
DEPARTMENT OF CERMISTRY THE CITYCOLLEGE THE COLLEGE OF T R E CITYOF NEWYORK RECEIVED AUGUST25, 1938 NEWYORK, N. Y .
The Classidcaeon of Chelating Groups
The Structure of Lignin B. C-ER, M. J. HUNTERAND HAROLDHIBBERT In a recent note1 the 3ohtjon of a new aromatic
B Y A.
(1) Cramer, Hunter and Hibbert,
TSIS J
~
~
A
DIVISIONOF INDUSTRIAL AND CELLULOSE CHEMISTRY MCGILLUNIVERSITY RECEIVED OCTOBER 18, 1938 MONTRSAL,CANADA
80,2274 L , (185s).
HgLMUT
M*HAENDLER
AND
*'
GEYER
In the course of preliminary work on organic analytical reagents which form inner complex
NOTES
2814
compounds with metal ions, it was found advisable to devise a system for the classification of chelating groups present in various organic compounds to serve as a basis of comparison. The available classifications, in particular that of Diehl,' are too unwieldy for rapid grouping and comparison. In addition to classifying the organic compounds now known, any system should also present information concerning possible reTABLEI Group designation
C-N, SH C-NH, SH C-NOH, OH N-NONHd, 0 C,C-N, NOH C,C-N, OH C,C-N, SH C,C-NH, SH C,C-NHs, OH C,C-NOH, NOH C,C-NOH, 0 C,C-0, OH C,C-0, SH C,C-OH, OH C,C-OH, S C,N-NH, NOH C,N-NHn, OH C,N-NHe, SH C,C,C-N, NH C,C,C-NOH, OH C,C,C-0, OH C,C,N-N, NH C,f,N-NH, NH C,C,N-NH, NH1 C,C,N-NH, 0
Representative compound
M ercaptobenzo thiazole Rubianic acid Benzohydroxamic acid Cupferron (A) Phenyl a-pyridyl ketoxime 8-Quinolinol (B) 8-Quinolinethiol Thionalide Glycocoll Dimethylglyoxime (C) a-Nitroso-P-naphthol Oxalic acid Thioglycolic acid Catechol Thiohydantoic acid Nitrosoguanidine Hydrazinecarboxylic acid Dithizone (D) Chlorophyll type Salicylaldoxime (E) Alizarin Phthalocyanine Biguanidine Biuret Dicyandiamidine (F)
VOl. 60
agents. The common method of indicating the number of members in the completed chelate ring is too cumbersome, in view of the recent increases in both number and variety of compounds possessing groups capable of chelation. In this classification the two functioning groups, which supply the primary and secondary valences involved in the general formation of a chelate ring, and the atom or atoms linking these two groups form the basis of the system. Compounds with identical chelating groups have the same group designation, regardless of the structure of the remainder of the molecule. The group designation is derived as follows: (a) The atom or atoms connecting the two functional groups are expressed by their conventional symbols, arranged alphabetically. ( b ) The functioning groups are given by their symbolic representations in alphabetical order of the atoms by which they are attached to the original compound before chelation. In salicylaldoxime, for example, the functional groups are linked by three carbon atoms, and these functional groups are the oxime and hydroxyl radicals. Consequently, the classification is C,C,C-NOH, OH. The accompanying list gives in order of increasing complexity the designations of the more common chelating groups and the names of representative compounds containing such groupings. For the sake of clarity, structural formulas illustrating some of the inner complexes formed are also given. It is evident that exact knowledge of the structure of the chelate compound formed is not essential for this method, insofar as the primary and secondary valence connections are concerned. No attempt is made to designate these linkages as to type, and compounds are arranged solely on the basis of general structure. DEPARTMENT OF CHEMISTRY
UNIVERSITY OF WASHINGTON SEATTLE, WASHINGTON
RECEIVED JULY 29, 1938
Dynamic Isomerism of Acetaldehyde 2,4Dinitrophenylhydrazone BY W. M. D. BRYANT
(E) (1) H.Diehl, Chcm Rm.. '21, 39-111 (1937)
(F,
In earlier papers the presented conclusive evidence based on optical crystallographic measurements that there are a t least two distinct crystalline modifications of acetaldehyde 2,4(1) Bryant, THISJ O U R N ~ L ,56, 3201 (1933). (2) I b i d . , 18, 2335 (1936).
