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Coulometric Micro and Ultramicro Determination of Hydronium Capacities of Ion Exchangers.

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120-125 'C without melting and is moderately soluble in
common organic solvents; it crystallizes readily from CH2CI2.
The structure proposed for ( 3 ) is in agreement with its
simple infrared spectrum: terminal CO-groups absorb at
2137, 2092, 2070, 2058, and 2024 cm-1, the SOz-group at
I209 and 1048 cm-1.
SO;?is a weaker electron donor than carbon monoxide. This
is confirmed by the lower stability of (2) compared with ( I )
and by the fact that the CO-stretching frequencies of (2) and
( 3 ) are higher than those of the corresponding unsubstituted
carbonyl compounds.
Received, March 7th, 1963
[Z 461/284 IE]
[l] H . W. Sternberg, R . A . Friedel, R . Markby, and I. Wender, J.
Amer. chem. SOC.78, 3621 (1956); regarding structure, cf. A . A .
Hock and 0. S. Mills, Acta crystallogr. 14, 139 (1961).
[2] E . Weiss, W . Hubel, and R . Merinyi, Chem. Ber. 95, 1155
(1962).
[3] W . Hieber and J. Gruber, 2. anorg. allg. Chem. 296, 91 (1958).
dimeric t-butylimino-chloroarsane m.p. 61 -64 OC according
to equation (d) [4].
( ~ - C ~ H ~ N = A S - N R+~4) HCI
Z + ( ~ - C ~ H ~ N = A S +2RzNH'HCI
CI)~
(d)
Received, March 11th. 1963
[Z 464/291 IE]
[I] G. Kamai and Z . 1,. Khisnmova, Doklady Akad. Nauk SSSR
105, 489 (1955).
I21 Z.Bourgeoise and J. Holle, Mem. Serv. chim. Etat 34, 411
(1948).
[3] H. J. Vetfer and H . Niith, Angew. Chem. internat. Edit. I ,
663 (1962).
[4] G. Ohlah and A . Oswald, Canad. J. Chem. 38, 1428 (1960).
A Simple Method for the Preparation of Ethers
from Phenols
By Dr. E. Vowinkel
Institut fur Organische Chemie
der UniversitPt Kiel (Germany)
The Reactivity of Alkylaminoarsanes
By Dr. H. J. Vetter, H. Stramelz, and Dr. H. Noth
Institut fur Anorganische Chemie
der Universitat Munchen (Germany)
Transamination of As[N(CH3)2]3 ( I ) [l] with secondary
amines HNRz proceeds faster as the bulk of R decreases.
With piperidine in boiling benzene, reaction (a) is completed
within 3 hours, but interaction with excess HN(C2Hs)z or
HN(CaH9)z requires longer heating.
AsIN(CHd2h
+ 3 HNRz
+ As(NRzh
+ 3 (CHdzNH
(a)
(1)
The following aminoarsanes are accessible in good yields by
this route: As[N(C2H5)2]3 111, b.p. 73"C/0.5 mm; n g =
1.4839; As(NCsH&, b.p. 139-142 OC/O.Ol mm, m.p. 49 to
51 OC; and As[N(n-C4H9)2]3, b.p. 159-161 oC/O.Ol mm, n g =
1.4789. These react with carbon disulfide to give tris(dialky1dithiocarban1idato)arsanes [21, As[S-C(S)-NR&
(R = CH3,
m.p. 240°C; R = n-C4Hg, m.p. 124°C; Rz
-(CH2)5-,
m.p. 230OC). The rate of reaction decreases rapidly in the
series N(CH3)2 > NCsHio > N(C4H9)2, which indicates the
influence of steric factors.
Transamination of ( I ) with primary amines [3] yields cyclic
aminoarsanes. The nature and size of the rings depend
mainly 1'0 steric effects. Thus, reaction of ( I ) with bulky tbutylamine proceeds, (in contrast to the reaction with nC4H9NHz [3]) by way of (CH&NAs(t-C4HgNH)2 (b. p.
67 'C/O.Ol mm, n2,o = 1.4717), to a stable dimer, dimethylamino-t-butyliminoarsane (2), b.p. 111-1 13 "C/O.S mm,
n 3 = 1.5148.
Phenols form aryl alkyl ethers when treated with primary
alcohols in the presence of dicyclohexylcarbodiimide [l].
Originally [I] it was stated that room temperature and an
inert solvent are required.
Considerably better results are obtained when the reagents
are heated together at 100 110 " C in the absence of solvent.
The yields of ether after 24 hours (Table 1) lie in the region
of 84-91 % for m- and p-substituted phenols. o-Substituted
phenols require 2-4 days heating before yields of the same
order are obtained. The ethers are isolated from the reaction
mixture by chromatography on acidic activated alumina.
Using n-pentanelmethylene chloride as eluant, the ether is
in the first fraction in a slate of extraordinary purity [2].
After removal of the solvent, the crystalline ethers have the
correct melting point; even veratrol (m. p. 22.5 "C)is obtained
in crystalline form. Liquid ethers are also completely pure
without further distillation (refractive index).
Table 1. Yields of phenolic ethers by the carhodiimide method at 100 to
110 "C.In each case, 1 .O mole oC phenol. 1.2 mole of alcohol and 1.1 mole
of dicyclohexylcarhodiimide were reacted together in a sealed tube
1 I
7
2 As[N(CH3)213
+ 2tGH9NHz
\
91
91
85
78
90
84
85
I
Time of
reaction
[days]
I
I
I
Phenol
p-Methoxyphenol
m-Methoxyphenol
Guaiacol
pCresol
m-Cresol
a-Cresol
Methano!
84
88
87
76
87
85
86
Received, March lath, 1963
[Z 4651294 IE]
[l] E. Vowinkel, Chem. Ber. 95, 2991 (1962).
[2] After a long interval, a second fraction consisting of unreacted alcohol comes off the column. Phenol residues, carbodiimide, and the N,N'-dicyclohexylurea formed, as well as 0aryl ethers of N,N'-dicyclo hexylisourea remain at the top of the
column.
-4(CH9)7NH
(2)
Dimeric t - butylamino - t - butyliminoarsane, b. p. 125 "C/
0.01 mm, m. p. 80--85 "C cannot be obtained by transamination, but is readily prepared according to equation (c).
2 AsCl3
+ 10 t-C4H9NHz
Coulometric Micro and Ultramicro Determination
of Hydronium Capacities of Ion Exchangers
t-CdH9NH-As-N-C.+Hg-t
+
I
t-CqH9 -N-As
I
--NHGHg-t
By Dr. B. Sansoni
(C)
13)
Chemisches Institut der U niversitat Marburg/Lahn(Germany)
+ 6 t-C4H9NHz'HCI
Hydrochloric acid splits the As-N bonds in (2) and ( 3 )
selectively. When used in stoichiometric quantities, it affects
the exocjclic As-N bonds preferentially, and produces
218
Hydrogen ions are eluted from the H+-form of a cation
exchanger with a concentrated solution of a neutral sodium
salt according to:
H+-resin + Na+
Angew. Chem. internat. Edit.
+
Na+-resin
+ H+.
Vol. 2 (1963) I No. 4
The hydronium ions in even very small volumes of the eluate
can be removed continuously from the equilibrium by
hydroxyl ions produced coulometrically [l]. This allows
simple but sensitive and accurate determinations of the hydronium capacities of ion exchangers.
Nitrogen is bubbled through 10 ml of a 1 N solution of
sodium chloride in a micro cell equipped with a generating
electrode (Pt, 1 cmz), a micro glass electrode, and a salt bridge
(agar-agar/saturated potassium chloride solution) linked to
an external reterence electrode (platinum in 0.2 N sodium
chloride). The solution is titrated to pH 6.00 s i n g a coulometer E 211 (Metrohm). After adding the H'-form of the
ion exchanger, it is again titrated to this p H with 0.03 to
10 mamp [2].
The capacities determined for a strongly acid ion exchanger
(Lewatit S 100, hydronium form, 1-150 mg) agreed with the
values obtained volumetrically using 1.25 g of resin according
to [3]. The relative standard deviation of a single value [4] in
24 determinations with 7.5-150 mg was found to be j, 0.86
to t 0.04 %. This is more accurate than the j, 3.5 "/, found
for 8 volumetric macro determinations [2].
The coulometric method makes it possible to determine the
hydronium capacities of single resin beads of sizes down
to 0.2mm diameter. Capacities of 13x 10-9 to 53x 10-9 equivalents per bead or 2.4-6.3 micro equivalents per mm3 of
spherical bead were found for the hydronium form of Dowex
50W X 2 (0.20-0.25 mm in diameter, 90 determinations).
The relative standard deviations of single values of the volume
capacities lay between =k 12 and & 54 %, and those o f the
average between+ 1.3 and+ 5.7 % [2]. By way of comparison,
the former values for cobalt capacities were i 3.0 to rt 6.1
when measured radiometrically with cobalt-60 on 87 beads.
The greater fluctuation of the H+-values compared to those of
Co2+is due.partly to the lower precision of the coulometric
method and partly to actual variations in the occupation
of surface sites with hydronium ions.
The determination of the hydronium capacity of a single bead
of resin of 0.5-0.2 mm diameter is a n instructive lecture
demonstration of the sensitivity of coulometric titrations.
The compounds can be distilled at atmospheric pressure
without decomposition at bath temperatures of up to 200 "C.
I-Chloroborolane (b. p. 96-100 " C ) crystallizes after distillation, but 1-chloro-3-methylborolane(b.p. 110-1 12 "C)
is obtained in the solid form only by cooling the distillate
rapidly to -49 "C. Generally the liquid is initially mobile but
slowly becomes very viscous at room temperature. The polymeric compounds formed which may involve ring and chain
structures, depolymerize again in the presence of BHcompounds or on heating. In dilute solutions, e . g . in cyclohexane or benzene, the compounds are monomeric (cryoscopic molecular weight determination). With LiAlH4, 1chloroborolanes give bis-borolanes [3] in high yields.
Dehalogenation, e . g . with Na/K alloy at room temperature in hexane, also gives BH-compounds. Resides bis~ B161
) 2 cni I ) , 2-borolanylborolane
borolane ( v ~ ~ ~ ( B H =
(Vmax(BH2B) = 1575 cm-1) is also formed. Starting from
l-chloro-3-methylborolane,a trinier o f molecular formula
C15H27B3 can also be detected in the mixture of products
by mass spectrometry.Theseboron hydrides (e.g.bis-borolanes
above 110°C) react stepwise with ethylene to give the Bethylborolanes ( I ) and (2).
x,
Received, December 7th, 1962
[Z 406/282 IE]
[I]J. J. Lingane: Electroanalytical Chemistry. 2nd Edit., Interscience, New York 1958; K. Abresch and L. Classen: Die coulometrische Analyse. Verlag Chemie, Weinheim/BergstraOe, 1961.
[2] To be published in detail in Z. analyt. Chem.; measurements
made in collaboration with H. Schiemnnn.
[3] S. Fisher and R. Kunin, Analytic. Chem. 27, 1191 (1955).
[4] G. Gottschalk: Statistik in der quantitativen chemischen Analyse. Enke-Verlag, Stuttgart 1962.
1-Chloroborolanes
By Dr. R. Koster and Dr. G . Benedikt
Max-Planck-Institut fur Kohlenforschung,
Mulheim/Ruhr (Germany)
B-Chloroborolanes are obtained in about 90 % yield from
a,w-diborolanylalkanes [I] and boron trichloride (equimolar
proportions) in the presence of BH-compounds [2], e. g . bisborolane [3], at 120-140°C.
Angew. Chern. internat. Edit. / Vol. 2 (1963)
1 No. 4
li
I t = CI13; b.p. 85"C/O,3mm
In the presence of BH-compounds, or on heating after dehydroboration, ( 2 ) disproportionates into B-ethylborolane
and high-boiling compounds with three boron atoms; we
assume a structure corresponding with (3).
Similar products are formed on dehalogenation of dialkylchloroboranes with Na/K-alloy ; a compound proposed
previously, potassium di-n-butylborane 141, could not be obtained. Under very mild conditions, at first BH-compounds are
obtained which are soluble in hydrocarbons and ether
(v,,,(BH~B)
= 1565 cm-1). These are then transformed into
sparingly soluble complexes (v,,,(BH)
= 1900-2050 cm-1,
broad), which on deuterolysis afl'ord 94 ZHDbesides 6 % D2.
This precludes the presenceofessential amounts of compounds
with B-K bonds.
Received, February 14th, 1963 [Z 444/274 IE]
[I] R . Koster, Angew. Chem. 7 1 , 519 (1959).
[2] R. Koster, Angew. Chem. 73, 66 (1961).
[3] R. Koster, Angew. Chem. 72, 626 (1960).
[4] R. Aufen and C. Kraus, J. Amer. chem. SOC.74, 3398 (1952).
219
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hydronium, exchanger, ion, micro, capacities, determination, ultramicro, coulometric
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