1492
VOl. 59
WILLIAM H. HAMILL
ammonia, and in this respect the latter possesses a distinct advantage over either an aqueous or organic medium in carrying out the alkylation reactions studied in this investigation. By using the alkyl p-toluenesulfonates and alkyl sulfates as alkylating agents, this advantage is combined with the facts that the alkylations are capable of being carried out a t atmospheric pressure, and that the final product as obtained directly from the reaction mixture is in a high state of purity. The latter presents a serious problem when alkylating with the alkyl halides, due to the difficulty in separating them from the desired product by fractionation. This is especially true in the case of the alkylacetylenes. The preparation of i-propylacetylene by means of i-propyl sulfate represents, as far as is possible to ascertain, the first direct method for the synthesis of this compound. Investigations will be continued along this line in an attempt to syn-
[CONTRIBUTION FROM THE
thesize various branched chain alkyl acetylenes by means of the appropriate alkyl sulfates.
Summary The alkylation of acetylene, phenol and alcohols has been accomplished by means of the alkyl esters of p-toluenesulfonic acid and sulfuric acid in liquid ammonia. It has been found that'the yields are increased considerably by increasing the molal ratio of compound alkylated to ester used, the best yields resulting when this ratio was 2 : l . &Propyl sulfate has been employed for the synthesis of the corresponding branched chain alkyl acetylene. A modified method for the preparation of nbutyl p-toluenesulfonate has been described. A convenient method has been given for the synthesis of n-propyl and i-propyl sulfates. RECEIVED JUNE 7, 1937
NOTRE DAXE, INDIANA
DEPARTMENT OF CHEIMSTRY, FORDHAM UNIVERSITY]
Equilibria in Protium Oxide-Deuterium Oxide Mixtures BY WILLIAMH. HAMILL
Ionization of a Weak Acid in H20-D20.-The dissociation equilibrium expression for a weak acid in aqueous medium of normal isotopic composition is expressed satisfactorily in the conventional manner: K = (H+)(A-)/(HA). For isotopic mixtures an apparent equilibrium constant (ICap.) is defined in terms of all isotopically variable molecular species involved in the component equilibria. In general, for the isotopically distinct reactants 4, Bi,. . and products X,, Yi,. . this is (1) and becomes (2) for a weak monobasic acid.
.
.
appears below. The evaluation of Ks, K4,Kg depends upon a knowledge of &,for H20-D20mixtures. K3 can be determined at small deuterium concentrations where R is very small and (sa) becomes approximately
In the limit for deuterium oxide the product is obtained since (Sa)becomes
IC&&
KsKXX7IKs * K d K m
+
+
(8~)
-
TABLE I
HaO+ HDO = HaDO+ HIO; (HIDO+) KiR(HaO+) (3) HzDO+ HDO = HD,O+ HnO; (HDrO+) = K:KaRZ(HiO+)
+
+
+ HDO = DsO+ + HtO; HA + HDO = DA + HzO; HzO + Dz0 = 2HDO; QHz + HDO = QHD + Hz0; QHD + HDO QDt 4- S O ; HzDO+ + Dz0 = D30+ + H20; €bo++ DtO HDaO+ + HtO; HDtO+
(2)
In terms of equilibria (3) to (7) of Table I, where R = HDO/H20, equation (2) is simply resolved and becomes (8a). An exchange constant of the Kap.= Ks (sa)
type Ka ordinarily can be determined by experiment or from spectroscopic data, or indirectly as
-
etc.
-
(DsO+)
-
(4)
KIKIKIR~(HJO+)
(DA) = KsR(HA)
(5) (6)
K~
(7)
-
K9
337
(9)
Ku K K
-
K4KaK7 KaKdC,
(10) (124 (12b)
K4 is obtained readily at intermediate HzO-DzO concentrations. It is clear that Ke is the only variable a t constant temperature which is required to fix the ratio K D J K H A .
Aug., 1937
EQUILIBRIA IN PROTIUM OXIDE-DEUTERIUM OXIDE MIXTURES
Acetic Acid.-Such calculations have been performed with the conductance data for acetic acid of La Mer and Chittum.’ Their log Kap. vs. ND20is sufficiently linear to permit accurate interpolation of Kap at small heavy water concentrations. An experimental determination of Kg for acetic acid is lacking but it can be determined simultaneously with K3from 8b. Equilibrium constants have the following values: K3 = 0.93, K4 = 0.344, K6 = 0.138, Ke = 0.475. These values will be used hereafter as required. Calculated and observed values of Kap.,compared in Fig. 1, agree satisfactorily. In all graphs circles are experimental, curves are calculated.
1493
calculation of Kap for the mixtures HnO-D20. In Fig. 2, 0.030 log K i p / K a ~is * in fair agreement with observed increments in e. m. f. The failure of this equation to account for the experimental minimum may be due to the unavoidable simplifications involved.
0
I
I
I
0.25
0.50
0.75
J
10
ND*O= AS/O.1079. Fig. 2.
The Hydrogen Electrode.-The behavior of the hydrogen electrode6 in Hz0-D20 can also be described by analogous treatment. (Haof HtDO+ H&O+ DaO+)* (PHI PED 4- fi~t)(HzO HDO DO)’ = Knp ’ f l KsR t mrJ&J!* K3K4K&Ra)’ 0
0.25 0.50 0.75 ND,O = AS/0.1079.
1.0
Fig. 1.
The Quinhydrone Electrode.-The
typical equation (Sa) may also be applied*to the e. m. f. measurements on the quinhydrone electrode by Korman and La Mer.s There are, however, the added difficulties of a dibasic acid which requires two exchange constants and the unknown solubilities of quinone and hydroquinone (QHr) for the mixtures H20-D20. By disregarding variations in the solubilities and by applying a pseudo exchange constant,‘ (Sa) may be applied to the (1) La Mer and Chittum, THIS JOURNAL, 68, 1642 (1933). (2) Equation (1) has better justification for practical rather than for theoretical reasons. Although thk expression seems to correspond to the one obtained by La Mer and Chitturn,] it d a s not appear t o bear any simple relation t o the electrode reactions t o he considered below for which the experimental apparent equilibrium conb .n is the numstants are of the type K l K k . K ; , where LI bet of faradays for the electrode reaction which has A, 13,. . N isotopic variations. Empirically, however, (1) satisfactorily describes these e. m.f. measurements without requiring any obviously empirical constant. (3) Korman and La Mer, THISJOURNAL, 68,1396 (1936). (4) Since Kap. for this dibuic a d d includes the term (PHI QHD 4- pa) = (1 KsR KoKnR*),by (9)and (10) Table I, it is first AR)2. Hydronecessary to assume (1 9 K& KdGoRI) = (1 quinone may then be treated as a monobasic acid (QH)for wbich K Q H I K Q D 0 3.84 a n d A Isr 0.56,
+ +..
..
+
-
-
+
+
+
+
+
+
+
+
+ 0.309R + 0.0292R*)(1 + R + Rz/K?)z=
Kep.’KHS
‘
The ratio K i r p / K H + approaches 0.76 in the limit as compared to the experimentally extrapolated value of 0.77. The behavior of this ratio in terms of e. m. f. vs. ND,0 is a good description of, the experimental curve (Fig. 3). The behavior of
.
+
+
(1
+ +
0
0.25 0.50 0.75 ND~= O AS/0.1079. Fig. 3.
1.0
( 5 ) Abel, Bratu and Redlich, 2 . phrsik. Chcm., A1711, 353 (1935). ( 6 ) The requisite equilibrium constants were taken from Farkas’
“Light and Heavy Hydrogen,” Cambridge University Press, don, 1986, pp. 189 ff.
Lon-
F. W.BEBGSTROM AND ALANMOFFAT
1494
the hydrogen electrode in alkaline media may be described similarly once the exchange constant for the hydroxyl ion has been evduated from the e. m. f. data. This constant has the value K = 0.348. Calculated and experimental values, in good agreement, are compared in the upper curve of Fig. 3. Hydrogen Ion Equilibria.-The following expression (9a) is of considerable interest. It is
+ HDOD+ + DzOD+)(HzO) + HDOH+ + DlOH+)(RDO)=
(HIOD' (H*OH+
+ +
Kap'
+ +
E
K8 @a)
(K: KaK4R KaKXsR*) cI K, (Qb) (1 K& KsK4R') readily converted to (9b) and Kap,is Seen to have the limiting values KO = Ka = 0,93in HpO and Ks Kr 0.138 in DoO. This equilibrium has been expressed in the simplified manner of (lo),*#' In accordance with the considerations above, however, KIO must be considered the limiting value in DnO of an apparent constant and is not to be
- -
(7) Hnmill and La Mer, 1.Chum. Phys., 4, 896 (1936).
VOl. 59
confused with (11) which is a true equilibrium expression (if the existence of HaO+, etc., be granted).
The various equilibria involved in the conductance of strong acids* are readily evaluated. In addition to the fundamental equilibria (3, 4, 5 ) there are the equilibria (12),Table 1. The author is grateful to Prof. V. K. La Mer for helpful criticism,
8-w Upon the basis of the assumed existence of the ions €bo+,H,DO+, HDsO+ and D,O+ it is poosible to describe consistently the behavior of conductance and e, m,f. data in HsO-DgO mixtures in terms of the various isotopic equilibria. (E) Baker .nd La Mer, ibid., 8, 406 (l9S6).
Nsw Yom, N. Y.
RECEWVED JUNE 1, 1937
[CONTIUBUTION FROM TEE CKEMXCAL LABORATORY OF STANFORD UNIVERSITY]
Claisen Type Condensations with Quinaldine and Related Ammono Ketone Ethers BY F. W. BERGSTROM AND ALAN MOFFAT Quinaldine, C",
