Effect of the structure of functionalized phosphoryl carriers on the membrane transport of proton-donor substrates

Article abstract of DOI:10.1134/S1070363206100057

A series of phosphoryl compounds functionalized in the side chain were synthesized, and their membrane-transport properties with respect to proton-donor substrates of various acidity were studied. It was found that the efficiency of phase transport of the strong monobasic perchloric acid correlates with the basicity of the phosphoryl carriers in a series of carriers containing oxygen-containing functional groups. The transport flow sharply increases in going to phosphorylated amines, whereas phosphoramidates in their efficiency are closer to phosphonates than to amines. The efficiency of transport of dibasic acids (oxalic and tartaric) is low, since the hydroxy and carboxy groups not bound to the carrier make ionic associates highly hydrophilic. Fine details of the structure-transport acitivity relationship in the series of phosphorus compounds were discussed. Three-dimensional correlation analysis was used to compare the structure of the carriers with their characteristics: basicity of amine centers, atomic charges of oxygen and nitrogen, and hardness and hydrophobicity parameters. Nauka/Interperiodica 2006.

Full text of DOI:10.1134/S1070363206100057

ISSN 1070-3632, Russian Journal of General Chemistry, 2006, Vol. 76, No. 10, pp. 1537 1544.
Original Russian Text R.A. Cherkasov, A.R. Garifzyanov, N.S. Krasnova, A.R. Cherkasov, A.S. Talan, 2006, published in Zhurnal Obshchei Khimii,
006, Vol. 76, No. 10, pp. 1603 1611.
Pleiades Publishing, Inc., 2006.
2
Effect of the Structure of Functionalized Phosphoryl Carriers
on the Membrane Transport of Proton-Donor Substrates
a
a
a
R. A. Cherkasov , A. R. Garifzyanov , N. S. Krasnova ,
a
b
A. R. Cherkasov , and A. S. Talan
a
Kazan State University, ul. Kremlevskaya 18, Kazan, 420043 Russia
e-mail: rafael.cherkasov@ksu.ru
b
Unversity of British Columbia, Vancouver, Canada
e-mail: artc@interchange.ubc.ca
Received February 26, 2006
Abstract A series of phosphoryl compounds functionalized in the side chain were synthesized, and their
membrane-transport properties with respect to proton-donor substrates of various acidity were studied. It was
found that the efficiency of phase transport of the strong monobasic perchloric acid correlates with the basicity
of the phosphoryl carriers in a series of carriers containing oxygen-containing functional groups. The transport
flow sharply increases in going to phosphorylated amines, whereas phosphoramidates in their efficiency are
closer to phosphonates than to amines. The efficiency of transport of dibasic acids (oxalic and tartaric) is low,
since the hydroxy and carboxy groups not bound to the carrier make ionic associates highly hydrophilic. Fine
details of the structure transport acitivity relationship in the series of phosphorus compounds were discussed.
Three-dimensional correlation analysis was used to compare the structure of the carriers with their character-
istics: basicity of amine centers, atomic charges of oxygen and nitrogen, and hardness and hydrophobicity
parameters.
DOI: 10.1134/S1070363206100057
Liquid and membrane extraction play an important
role in technological processes involving concentra-
tion and selective separation of mineral, organic, and
biological substrates. The most common extractants
and carriers for the latter are neutral organophosphorus
compounds, such as tributyl phosphate and trioctyl-
phosphine oxide [1], as well as polyether podands
with terminal phosphoryl groups [2]. In a series of
previous works we showed that - and -aminated
phosphoryl compounds exhibit a high efficiency in
phase transport. This equally relates to liquid extrac-
tion of metal ions [3] and mineral acids [4], as well
as to transport of inorganic acids through liquid
membranes [5]. Of particular importance is that re-
search into phase transport of acids is quite urgent,
since separation of, for example, metal ions by means
of liquid and membrane extraction is most frequently
performed from aqueous solutions of mineral acids
functional groups that, too, can serve as coordination
centers. These substituents differ in electronic nature
and, on the one hand, exert different effects on the
basic phosphoryl center and thus predetermine its co-
ordination power and efficiency of the carrier as a
whole, and on the other hand, can function as com-
petitive and additional coordination centers. We
studied the membrane-transport properties of a series
of phosphoryl compounds R P(O)R (I XIII) func-
2
tionalized in the side chain, with respect to acids of
various nature, viz. the strong monobasic perchloric
acid, two medium-strength dibasic organic acids
oxalic and tartaric, and a relatively weak proton donor
having, in addition, a potentially alternative basic
amine center, aminoethanol that can act both as proton
donor and proton acceptor. Table 1 lists the formulas
of the radicals R and R and experimental and cal-
culated characteristics of the corresponding carriers.
[
5, 6].
The organophosphorus carriers studied in the
present work were synthesized using traditional
methods of organophosphorus chemistry [7]. Tri-
octylphosphine oxide (I) was prepared by the reaction
of phosphorus oxychloride with octylmagnesium
bromide, and phosphonates II IV, by the Michaelis
In the present work we studied substituent effects
on transport properties with respect to acidic sub-
strates of compounds of the phosphonate and phos-
phine oxide structure, containing, along with phos-
phoryl, other donor oxygen- and nitrogen-containing
1537

1538
CHERKASOV et al.
Table 1. Transport flows of substrates and calculated characteristic of carriers R P(O)R
2
Substrate transport flow
1
0 , mol m min 1
6
2
Comp.
no.
Total
hardness
R
R
logP
pKb
perchlo- oxalic
tartaric ethanol-
ric acid
acid
acid
amine
I
II
III
IV
V
Oct
Oct
140
0.43
0.89
1.6
97
0.60
17
280
49
35
32
80
5.0
2.04
1.80
66
63
49
114
5.32
1.46
1.74
0.45
6.2
9.20 221.26
11.92 230.64
9.53 206.93
9.35 230.54
7.22 206.82
7.51 213.74
7.51 200.94
7.79 204.42
11.09 220.25
8.98 199.11
10.04 202.54
10.71 250.62
10.87 263.52
2.91 120.57
2.99 119.39
0.63
0.69
0.65
0.74
0.65
0.69
0.66
0.73
2-Et-HexO Oct
2-Et-HexO CH OAm
2-Et-HexO CH O(CH ) OAm
Dec
6.1
0.50
0.46
0.75
0.10
0.02 241
0.10 372
0.17
0.32
0.11
1.4
2
2
2 2
CH OH
2
VI
DecO
CH OH
12.5
2
VII Dec
VIII DecO
IX
X
XI
XII 2-Et-HexO CH NBuOct
XIII DecO
XIV i-PrO
OH
OH
1.7
2-Et-HexO NBu2
2-Et-HexO NEt2
2-Et-HexO NHBu
0.55
0.22
2.5
420
407
0.37
0.38
0.34
0.65 0.61 7.40
0.69 0.64 7.25
0.67 0.60 7.17
0.74 0.03 9.55
0.67 0.04 9.37
0.64 0.58 1.91
0.65 0.46 1.35
105
98
2
CH NBu
0.03
11.1
2
2
NC(O)Ph
NC(S)Ph
XV
i-PrO
Becker reaction of sodium bis(2-ethylhexyl) hydrogen
phosphite with octyl bromide, chloromethyl pentyl
ether, and ethylene glycol butyl chloromethyl ether,
respectively. Hydroxymethyl derivatives V and VI
were prepared by the Abramov reaction of didecyl-
phosphinic acid and didecyl hydrogen phosphite,
respectively, with Paraform. Acids VII and VIII were
prepared by the oxidation of the corresponding hydro-
phosphoryl compounds with nitrogen dioxide. Amino-
phosphonates XII and XIII were synthesized by the
Kabachnik Fields reaction [8] and phosphoramidates
IX XI, by the Todd Atherton reaction [9].
Thus, in our opinion, we could account for a
variety of structural factors on such properties of the
chosen series of compounds as electronic effects of
substituents, their hydrophilicity and lipophilicity, and
role of competitive intramolecular hydrogen bonding.
The range of substrates on this stage of research
was restricted by hydrophilic compounds capable of
forming H complexes with the phosphoryl group. As
membrane solvent we chose the nonpolar tridecane,
which excludes the possibility of specific solvation of
both carriers and complexes that form in the
membrane phase.
We expected that changes in the basicity of the
phosphoryl group in polyfunctional organophosphorus
reagents, caused by different electronic effects of
substituents, as well as the presence in the molecules
of additional nitrogen- and oxygen-containing
groups, would specifically affect the membrane-trans-
port properties of each carrier to the chosen substrates.
As reference we took trioctylphosphine oxide (I)
which has a single potential coordination center, the
phosphoryl oxygen atom. Compounds III VI, XII,
and XIII contain additional basic coordination centers,
oxygen or nitrogen. In should therewith borne in mind
that in aminophosphonates XII and XIII the amino
group is more basic than phosphoryl [8]. Furthermore,
compounds V VIII and XI contain proton-donor
fragments that can form intramolecular hydrogen
bonds with the phosphoryl group [8] or intermolecular
hydrogen bonds with substrate molecules.
The results listed in Table 1 show that the transport
properties of the four-coordinate phosphorus deriva-
tives studied vary over a wide range. To explain the
resulting data, one should primarily account for the
nature of substrate carrier ionic associates formed in
the membrane phase. According to [10], there are two
mechanisms of extraction with neutral organophos-
phorus compounds, hydrate solvate and solvate,
depending on the strength of the acid. Perchloric acid,
like some other strong inorganic acids, is extracted by
the hydrate solvate mechanism, i.e. a species that
passes into the organic phase is ionic associate XVI
comprising the hydroxonium cation H-bonded with
O
O H--O=PR3
+
H
(ClO4 )
H O
C C
H--O=PR3
H O
O
XVI
XVII
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 76 No. 10 2006

EFFECT OF THE STRUCTURE OF FUNCTIONALIZED PHOSPHORYL CARRIERS
1539
the extractant phosphoryl group and the perchlorate
counter ion.
higher strength is determined by additional H bonding
with this oxygen atom.
H---O
Weak organic and inorganic acids are extracted by
the solvate mechanism which suggests formation of
H complexes XVII. In the case, the extraction ef-
ficiency will be controlled by the hydration energy of
the acid molecule and the energy of the H bond
formed, i.e. by the strength and hydrophilicity of
associate XVII. Most likely, such complexes are
formed between our studied carries and oxalic and
tartaric acids.
+
PR2
(
ClO ) H O
4
H
O
Bu
XIX
As noted above, the transport of oxalic and tartaric
acid occurs by the solvate mechanism. Here, too, the
basicity of the phosphoryl group is the key factor. In
particular, the transport flow of oxalic acid decreases
alone the series I IV, in parallel with the decreasing
basicity of the phosphoryl oxygen atom.
In the membrane extraction of perchloric acid, the
transport properties of the carriers should be affected
by the basicity of the phosphoryl group and the effect
of additional coordination. The highest transport flow
is characteristic of the strongest bases, -aminophos-
phonates XII and XIII, and it is 3 times higher than
that for phosphine oxide I. This is naturally connected
with the fact that the tertiary nitrogen atom in
Therewith, the effect of additional coordination
does not obviously reveal itself, since phosphonates
III and IV that contain, along with the phosphoryl
oxygen, other potential coordination centers transport
oxalic acid slower than unsubstituted phosphonate II;
the oxygen-containing functional groups function ex-
clusively as electron-acceptor substituents and decrease
the electron density on the phosphoryl center.
-aminophosphonates is more basic than the oxygen
atom in trioctylphosphine oxide. At the same time, it
should be emphasized that the transport properties of
aminophosphonates and the other carriers are not fully
correct to compare, since amino compounds extract
acids by a different mechanism: Like in the extraction
with higher aliphatic amines, a species that passes into
the organic phases is the ionic associate of the cor-
responding acid anion and protonated aminophos-
phonate. With perchloric acid, ionic associate XVIII
may occur.
The transport properties of phosphoryl compounds
with respect to oxalic acid are strongly affected by
proton-donor substituents that increase the flow more
than 3 times for phosphine oxide V and almost
2
orders of magnitude for hydroxy derivatives VI
VIII compared with reference phosphine oxide I. The
most probable reasons for this effect are competitive
H bonding of the phosphoryl oxygen in intramolecular
H complexes XX of hydroxymethylphosphoryl com-
pounds V and VI and dimerization of acids VII and
VIII in the membrane phase to form very stable cyclic
H complexes XXI, which is characteristic of oxygen
acids of phosphorus in the highest oxidation state [11].
O---H
+
N
(
i-OctO)2P
(ClO4 )
Oct
Bu
XVIII
H
O
P
O
O---H O
O H---O
Replacement of donor alkyl groups at the phos-
phoryl center by acceptor alkoxy groups (com-
pound pairs I and II, V and VI, and VII and VIII)
always appreciably decreases the transport efficiency
by decreasing the electron density on the phosphoryl
oxygen. The presence or absence of proton-donor
groups in the side chain of the carrier (cf., for example,
compounds III, IV, on the one hand, and V, VI, on
the other) has no considerable effect of the general
regularity: In oxygen-containing compounds, the key
role belongs to the electronic effect of the substituent
on phosphorus.
P
P
XX
XXI
Interactions of this type prevent formation of H
complexes between protic carriers with the fairly weak
oxalic acid, which makes the carriers less efficient.
With the strong perchloric acid, the described intra- or
intermolecular H bonding exerts no competitive
effects.
With tartaric acid, a similar tendency in the effect
of the structure of phosphoryl carriers on their trans-
port properties is observed. As would be effected all
carriers transport tartaric acid slower than oxalic, since
the former substrate is more hydrophilic, having hyd-
roxy groups that form H bonds with carriers. General-
The increase of the flow over the series II IV is
probably explained by additional coordination: Intro-
duction of it is not fully oxygen atoms make possible
formation of solvate complex XIX whose relatively
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 76 No. 10 2006

1540
CHERKASOV et al.
Table 2. Atomic parameters used in calculating pK for
organophosphorus amines
[14]), which makes it less basic. Note that recently
Sokolov et al. [15] reported the high mobility of the
NH proton in N-(thio)acyl(thio)amidophosphates.
b
b
Atom
H
R
Their pK values in aqueous ethanol are 7 11. More-
i
a
over, among numerous reactions characteristic of
these compounds, we found no no reactions where the
amide nitrogen atom exhibits its basic or nucleophilic
properties. According to [16], diisopropyl phosphor-
amidate and phosphoramidothioate, too, exhibit
pronounced acidic properties (mean pKa in 50%
ethanol 12.4).
2.10
2.10
2.45
3.05
4.60
2.74
2.26
0.30
0.77
0.67
0.66
0.62
0.94
1.10
0.76 0.06
0.08 0.04
2.46 0.11
9.54 0.24
9.82 0.71
3.50a
Csp
Car
3
Osp
Osp
3
2
Ssp
Psp
2
16.8a
3
The above findings explain the fact that in their
transport properties the phosphoramidate carriers
compare with phosphonates II and III, rather than
with phosphorylated amines XII and XIII. The reason
for such a high selectivity of oxalic acid transport
with phosphoramidates (as well as trioctylphosphine
oxide) is not clear. Probably, we deal here with more
complex hydrogen associates formed by the dibasic
acid and phosphoryl associates, whose structure
should be studied in more detail, and we plan this
work for future.
a
Calculated by Eq. (2).
ly, the monobasic perchloric acid is much more ef-
ficiently transported by all the organophosphorus
bases than dibasic acids. The obvious reson for this
phenomenon is the high hydrophilicity of H com-
plexes between phosphoryl carriers and substrates
containing additional proton-donor groups, hyd-
roxyls and carboxyls, that do not bind with carriers,
thus making the H-bonded associates formed by these
substrates with carriers highly hydrophilic. Notably,
even phosphorylated amines XII and XIII that are
quite effective carriers for perchloric acid radically
We tried to express the dependence of the transport
properties of the organophosphorus carriers studied
on their structure by means of three-dimensional
(
4 times) decrease the transport flow of oxalic acid
correlation analysis [17]. The basicities pK of phos-
phoramidates IX XI and aminophosphonates XII and
XIII were calculated by Eq. (1) [18].
b
and exhibit almost no transport activity with respect to
tartaric acid.
Bis(2-ethylhexyl) phosphoramidates IX XI occupy
special place in the series of phosphoryl membrane
carriers (Table 1). They most effectively transport
oxalic acid, while perchloric and tartaric acids have
much lower transport flows. It should be emphasized
that phosphoramidates rank much below the more
basic trioctylphosphine oxide and compare with bis-
N 1
b
i
pK
= 9.12 +
.
(1)
R N
3
2
i r
rc i
Here N is the number of atoms in a molecule; rc,
Nsp atom considered as the protonation center; r rc i,
distance between the ith atom and nitrogen; and
3
b
i
,
parameter reflecting the ability of an atom of a certain
(
2-ethylhexyl) octylphosphonate (II) in transport ef-
type to contribute to pKb.
ficiency with respect to perchloric and oxalic acids.
Our results are well consistent with the above-des-
cribed general regularities of the membrane transport
of acids with four-coordinate phosphorus derivatives.
Obviously, the amide nitrogen atom in phosphorus
acid amides scarcely exhibits basic properties and is
not protonated with even fairly strong acids. Moreover,
it is well known that strong electron-acceptor groups,
such as trifluouromethanesulfonyl, tosylcarbamoyl,
b
i
Table 2 lists the
values for all-type atoms
constituting the compounds studied (the atom types
are assigned according to [19]). For the Psp and Ssp
atoms whose parameters had not been known, we
calculated them by Eq. (2) taking account of their
electronegativity ( ) and covalent radius (R ).
3
2
i
i
b
2
=
32.14( i
2.17)R .
(2)
i
i
2
,4-dinitrophenyl, etc., in hydrazines [12] or secon-
dary amines [13] make these compounds strong NH
acids comparing in strength with carboxylic acids.
The nitrogen atom in phosphoramidates is bound with
the fairly strong electron-acceptor phosphoryl group
The calculated values are listed in Table 2. The
calculated pKb values of phosphorus amides and
phosphonamidates are listed in Table 1. For compari-
son we also give in Table 1 the calculated pK values
b
(
the * constants of the dialkoxyphosphoryl group
for two N-acylphosphoramidates XIV and XV. The
calculated basicity characteristic of nitrogenous bases
are well consistent with available experimental results.
vary within the range 1.78 2.21; for comparison, the
Taft constant of the 2,4-dinitrophenyl group is 1.9
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 76 No. 10 2006

EFFECT OF THE STRUCTURE OF FUNCTIONALIZED PHOSPHORYL CARRIERS
1541
Thus, phosphoramidates IX XI proved to be almost
interaction (transport) of perchloric acid with the
carriers can obviously be described in terms of the
hard and soft acids and bases concept.
neutral nitrogen compounds: Their pK span the range
b
7
.2 7.5. These values provide convincing evidence for
the phosphoryl rather than amine nature of the
proton-acceptor properties of these carriers. The cal-
culated basicity parameters of -aminophosphonates
Thus, the quantitative correlations between the
transport properties of organophosphorus carriers and
some of their characteristics obtained both experi-
mentally and theoretically allowed us to reveal a
number of above tendencies relating the structure and
properties of these compounds. At the same time, it
should be borne in mind that the structure membrane
properties for various carriers may not be un-
ambiguous and simple, since the efficiency of
membrane transport depends on a great number of
factors. In the case of acidic substrates, along with
basicity, the efficiency of membrane transport can be
affected, according to [22], by the viscosity of
membrane phase, surface tension on the interface, and
other characteristic that are not always readily
accounted for.
XII and XIII, pK 9.55 and 9.37, respectively, with
b
the experimental pK values of their conjugate acids
a
(
pK 4 6) measured in [8]. With N-benzoylphosphor-
a
amidate XIV and its thio analog XV, too, the cal-
culated pK values correspond to the experimental and
b
above-mentioned acidities in aqueous ethanol (pKa
9
11). The calculated basicity parameters of the latter
two compounds can be considered perceived with
caution, since they take no account of the resonance
interaction of functional groups, which is probably
quite considerable. These results provide evidence for
the adequacy of the calculation methods we used to
estimate the basicity of the nitrogen centers in the
carriers studied.
To assess the effect of the structure of phosphoryl
compounds on their transport properties with respect
to proton donors containing their own basic center,
amino group, we chose aminoethanol as substrate.
The undeniable advantage of this reference compound
is its high hydrophobicity. Furthermore, we found in a
special experiment, ethanolamine is not transferred
through hydrophobic membranes in the absence of
carriers.
We found that the oxalic acid transport flows with
five phosphorus nitrogen compounds IX XIII fairly
correlate with the basicity parameters of the latter
[Eq. (3)].
=
19.562pKb
83.191 (R 0.9794).
(3)
Regretfully, we failed to obtain fair correlations
for the other reaction series. This is not surprising,
since, as mentioned above, the character of complex
formation with different acids should vary from one
carrier to another and, strictly speaking, certain as-
sumption should be made in relating the transport
flows for each acid with all the carriers studied to a
single reaction series.
The results listed in Table 1 suggest that the effect
of carrier structure on the flow of this substrate is
quite different from what we observed with the other
acids, even though the general tendency of the flow
rate to increase with increasing basicity of the carrier
is preserved. This primarily relates to proton-donor
carriers, i.e. hydroxymethyl derivatives V and VI.
With these carriers, the flows are appreciable higher
that with other derivatives of close basicity, for ex-
ample, phosphorylated esters III and IV, whereas
with oxalic acid the opposite tendency took place.
However, this effect is especially clearly pronounced
with relatively strong acids, viz. didecylphosphinic
acid (VII) and didecyl hydrogen phosphate (VIII).
There is no doubt that this fact is explained by the
presence in the substrate molecule of a highly basic
amino group that forms salts or H complexes with the
corresponding protic functional groups of the carriers.
For the same reasons we could not reveal definite
correlations between the transport flows and the
charge on nitrogen and phosphoryl oxygen, as well as
the octanol water partition coefficients of the carriers
(logP), calculated in the present work as a measure
of the hydrophobicity of the latter (see Experimental).
At the same time, we found that the total molecular
rigidity parameters ( MOL) of the organophosphorus
carriers studied (Table 1), calculated by formula (4)
we proposed in [20, 21], correlate well with the per-
chloric acid transport flows [Eq. (5)].
1
(
4)
With phosphoryl compounds containing no proton-
donor groups, the transport rate decreases with de-
creasing basicity. No evidence for additional coordina-
tion for carriers with oxygen-containing substituents
was observed. Thus, the transport of aminoethanol
with phosphoryl carriers features the reverse acid
base relation: With acids, phosphoryl reagents act as
=
,
MOL
2
2
N 1
R + R
j
i
2
2
i 1
r
j i
=
6.2325 MOL
1283.2 (R 0.9794).
(5)
Correlation (5) gives us grounds to suggest that the
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 76 No. 10 2006

1542
CHERKASOV et al.
basic cariers, whereas aminoethanol is more effec-
tively transported by proton-donor (acidic) carriers.
software [5] by the equation
= tan V/S, where
tan is the slope of the concentration time kinetic
dependence; V, volume of the receiving phase; and S,
membrane surface area. The resulting flows are listed
in Table 1.
Our present results open up possibilities for pur-
poseful selection of molecular structure in carrier
substrate pairs for optimizing both the rate of mem-
brane transport and the selectivity of phase transport.
Naturally, research into complementary carrier sub-
strate relations cannot confined to compounds of
specific classes (in our case, acids and basic phos-
phoryl compounds) and should be extended to other
important objects, such as ion metals, amino acids,
and neutral and organoelement molecules. These
problems will be the subject of our further studies.
Synthesis and characteristics of organophos-
phorus carriers.
Trioctylphosphine oxide. mp 55 C (published
31
data [1]: 50 55 C),
P 50 ppm.
Bis(2-ethylhexyl) octylphosphonate (II). Bis(2-
ethylhexyl) phosphite, 37 ml, was added dropwise
over the course of 30 min to a mixture of 40 ml of
ether, 60 ml of benzene, and 2.57 g of metallic
sodium. After the metal had dissolved completely,
EXPERIMENTAL
16.38 g of freshly distilled octyl bromide was added.
The octanol water partition coefficients logP were
calculated by the MOE program (Molecular Opera-
tional Environment; Version 2003.10, Chemical
Computation Group Inc., Montreal, Canada, 2004),
and the charges of the nitrogen and phosphoryl
oxygen are determined by the PM3 method using the
MOE program.
The mixture was refluxed for 1 h and left overnight.
Sodium bromide that dropped was separated by cen-
trifugation, and the solution was washed with distilled
water (5.50 ml) and dried with sodium sulfate. The
solvent was removed in a rotary evaporator, and the
residue was distilled in a vacuum. Yield 70%, bp
164 C (0.2 mm Hg), n2 1.4475,
0
33.2 ppm.
D
P
Membrane extraction was studies using a beaker-
in-beaker temperature-controlled cell whose design is
described in [23]. Vladipor MFFK-4 porous filters
Bis(2-ethylhexyl) (pentyloxymethyl)phosphonate
(III) was prepared in a similar way from 35 g of
sodium bis(2-ethylhexyl) phosphite and 15.02 g of
(
Teflon matrix on a polyether support; pore size
.6 m) were used as the hydrophobic matrix for
chloromethyl pentyl ether. Yield 31.26 g (70%), bp
164 C (0.25 mm Hg), n2 1.4452,
0
22,3 ppm.
0
D
P
impregnated membranes; the source phase contained
a 0.2 M substrate solution and the receiving phase
contained doubly distilled water. The membrane was
impregnated with tridecane solutions of neutral
carriers. Substrate solutions were prepared by dis-
solving accurately weighed samples in doubly dis-
tilled water or by diluting more concentrated solutions.
When required, the substrate concentration was de-
termined more accurately by titrimetry. All carrier
solutions were prepared by dissolving accurately
weighed samples in corresponding solvents. Con-
ductivity measurements were performed at 25 C every
Bis(2-ethylhexyl) [(2-butoxyethoxy)methyl]-
phosphonate (IV) was prepared in a similar way
from 18.36 g of sodium bis(2-ethylhexyl) phosphite
and 10 g of ethylene glycol butyl chloromethyl ether.
20
Yield 16.23 g (65%), bp 175 C (0.25 mm Hg), nD
1
.4462,
22.3 ppm.
P
Didecyl (hydromethyl)phosphonate (VI). A mix-
ture of 0.2 g of metallic sodium, 60 ml of absolute
benzene, 17.5 g of didecyl hydrogen phosphite was
heated until the metal dissolved completely, after
which 1.45 g of Paraform was added with stirring.
The mixture was stirred for 3 h at 60 C. Excess
Paraform was filtered off, and the filtrate was washed
with distilled water (6.50 ml) and dried with sodium
sulfate. Excess Paraform and solvent were removed
on a rotary evaporator, and the residue was heated to
5
min using a conductometer.
Calibration dependences were obtained by measur-
ing the electrical conductivities of substrate solutions
of varied concentrations in a temperature-controlled
cell, after which electrical conductivity time linear
plots were constructed (25 C, R 10 k ).
8
0 C in a water-jet-pump vacuum to obtain an almost
pure hydroxyphosphonate VI as a colorless liquid.
Yield 50%. bp 168 C (0.25 mm Hg), n2 1.4523,
0
Measurement of membrane transport flow (typ-
ical experiment). The outer beaker of the cell was
loaded with a substrate solution and the inner beaker
equipped with the conductometer sensor, with 7.5 ml
of doubly distilled water; measurements were per-
D
P
25.6 ppm.
Didecyl(hydromethyl)phosphine oxide (V) was
prepared in a similar way from didecylphosphinic acid
and Paraform. mp 47 C,
54.8 ppm.
P
formed every 5 min. The flows
were calculated
using a specially developed Vizual UNMK 2002
Didecylphosphinic acid (VII) was prepared by
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 76 No. 10 2006

EFFECT OF THE STRUCTURE OF FUNCTIONALIZED PHOSPHORYL CARRIERS
1543
the procedure described in [24]. mp 84 C, and the solvent was removed on a rotary evaporator.
P
0
5
8
9.9 ppm (chloroform). Published data [24]: mp 85
6 C, 59.4 ppm.
Yield 26.4 g (76%), n2 1.4511,
25.7 ppm.
P
D
P
ACKNOWLEDGMENTS
Didecyl hydrogen phosphate (VIII). Nitrogen
dioxide obtained by the action of concentrated nitric
acid on a saturated solution of sodium nitrite was
barboted through a solution of 15 g of didecyl hydro-
gen phosphite in 20 ml of benzene until an intense
yellow color appeared. Benzene was removed on a
rotary evaporator, and the solid precipitate was twice
recrystallized from hexane to obtain 10 g (60%) of
compound VIII as colorless crystals. mp 47 C {pub-
The work was financially supported by the Russian
Foundation for Basic Research (project no. 04-03-
3
2906), Universities of Russia Basic Research Prog-
ram of the Ministry of Education and Science of the
Russian Federation, and Basic Research & Higher
Education Bilateral Program of the Ministry of Educa-
tion and Science of the Russian Federation and CRDF
(project no. REC 007).
lished data [25]: mp 46 47 C),
form).
0.9 ppm (chloro-
P
REFERENCES
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P
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P
1
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8
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RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 76 No. 10 2006