Synthesis and characterization of alkoxyethoxyphosphoryl amines

Article abstract of DOI:10.1080/10426500701613097

A series of potential polidentate ligands were developed. The alkoxyethoxy-phosphorylamines were prepared by phosphorylation of different amines with the appropriate dialkoxyethyl phosphite in a two-phase reaction. The characterization of these compounds was carried out by IR, Mass, and NMR spectroscopy. The properties of these compounds as a chelating agent were investigated by direct UV titration technique. Copyright Taylor & Francis Group, LLC.

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Phosphorus, Sulfur, and Silicon
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Synthesis and Characterization
of Alkoxyethoxyphosphoryl
Amines
Whei Oh Lin a , Antônio Fábio Vieira a , Fábio Bicalho
Cano a & Edson de Souza Coutinho a
a Departamento de Química , Instituto Militar de
Engenharia Praia Vermelha, Urca , Rio de Janeiro,
Brazil
Published online: 09 May 2008.
To cite this article: Whei Oh Lin , Antônio Fábio Vieira , Fábio Bicalho Cano & Edson
de Souza Coutinho (2008) Synthesis and Characterization of Alkoxyethoxyphosphoryl
Amines, Phosphorus, Sulfur, and Silicon and the Related Elements, 183:5, 1209-1217,
DOI: 10.1080/10426500701613097
To link to this article: http://dx.doi.org/10.1080/10426500701613097
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Phosphorus, Sulfur, and Silicon, 183:1209–1217, 2008
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500701613097
Synthesis and Characterization
of Alkoxyethoxyphosphoryl Amines
ˆ
´
´
Whei Oh Lin, Antonio Fabio Vieira, Fabio Bicalho Cano,
and Edson de Souza Coutinho
Departamento de Qu´ımica, Instituto Militar de Engenharia,
Praia Vermelha, Urca, Rio de Janeiro, Brazil
A series of potential polidentate ligands were developed. The alkoxyethoxy-
phosphorylamines were prepared by phosphorylation of different amines with the
appropriate dialkoxyethyl phosphite in a two-phase reaction. The characterization
of these compounds was carried out by IR, Mass, and NMR spectroscopy. The proper-
ties of these compounds as a chelating agent were investigated by direct UV titration
technique.
Keywords Dialkoxyethoxyphosphorylamine; dialkoxyalkyl phosphite; dialkoxy-
ethoxyphosphorylguanidine; phosphorylation
INTRODUCTION
Bidentate compounds containing a 1-phosphoryl-3-carbonyl group are
known to form colorful complexes with various metal ions.1 They
are powerful extractants for trivalent lanthanides and actinides, as
well as alkali metal cations.2,3 An alternation of the molecular struc-
ture might improve the extracting properties of these compounds,
such as the chelating capacity as well as their selectivity towards
different metal ions. We have reported the syntheses and prelimi-
nary complexation studies of the dialkoxyphosphoryl- guanidines and
isothioureas.4−6 Now, we will describe the synthesis and structure anal-
ysis of the potential polydentate alkoxy- and alkoxyethoxy- phosphoryl
amines.
Received 5 May 2007; accepted 17 July 2007.
We thank the Volkswagen foundation, DAAD, CNPq, and CAPES for their financial
support.
Address correspondence to Whei Oh Lin, Departamento de Qu´ımica, Instituto Militar
de Engenharia, Praia Vermelha, Urca, Rio de Janeiro, RJ, 22290-270, Brazil. E-mail:
wheiohlin@gmail.com
1209

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W. O. Lin et al.
RESULTS AND DISCUSSION
The reaction of alkoxyethanol with phosphorus trichloride without a
solvent gave the desired alkoxyalkyl phosphite (I) in good yield. Phos-
phites of high purity were obtained by vacuum distillation. The reaction
of guanidine with the dialkoxyalkyl phosphite in a basic condition in
a two-phase reaction involving carbon tetrachloride and water at room
temperature led to the formation of phosphorylguanidine (II). The phos-
phorylation of ethylenediamine and its derivative with the prepared
phosphites (I) under similar conditions resulted in the potential poly-
dentate ligands (III) and (IV), respectively.
Phosphorylamines (II), (III), and (IV) showed characteristic IR ab-
sorption peaks at around 3400 (N-H), 1200 (P O) and 1000 (P-O-C)
1
cm−1. The H NMR spectra showed the characteristic triplet peak at
around δ = 1.00 ppm for the terminal methyl group and a symmetric
multiplet at around δ = 4.00 ppm for the hydrogen atom of CH2OP ,
suggesting the presence of the coupling between phosphorus and hy-
drogen nuclei.6,7 All the hydrogen atoms connected to amino nitrogen
appeared as a broad peak at around δ = 6.0 ppm. The phosphites (I)

Alkoxyethoxyphosphoryl Amines
1211
TABLE I Spectroscopic Data for Phosphites and Phosphorylamines
(I)–(III)
Mass
Compound
ROCH2CH2O
CH3 OCH2CH2O
CH3CH2 OCH2CH2O
CH3CH2CH2CH2 OCH2CH2O
CH3CH2CH2CH2CH2O
CH3 OCH2CH2O
CH3CH2 OCH2CH2O
CH3CH2CH2CH2 OCH2CH2O
CH3CH2CH2CH2CH2O
CH3 OCH2CH2O
CH3CH2 OCH2CH2O
CH3CH2CH2CH2 OCH2CH2O
CH3CH2CH2CH2CH2O
31P-NMR (M++1)
Common peak
Ia
Ib
Ic
Id
IIa
IIb
IIc
IId
IIIa
IIIb
IIIc
IIId
7,20
5,41
6,98
4,00
8,68
8,42
8,66
6,80
11,42
11,65
11,27
10,75
199
227
283
223
256
284
340
280
453
509
620
83; 65
83; 65
83; 65
83; 65
140; 123
140; 123
140; 123
140; 123
226; 220; 110
254; 220; 110
310; 220; 110
500 (M+) 250; 220; 110
as well as the phosphorylated guanidines (II) and symmetric phospho-
rylamines (III) showed the molecular ion plus one peak in their mass
spectra. Table I shows the spectroscopic data for phosphites (I) and the
phosphorylamines (II) and (III). These compounds demonstrated frag-
mentation by McLafferty rearrangement to give characteristic common
fragments of m/e = 83 and 65 (Fig. 1) from phosphite (I) and common
peaks with high intensity at m/e = 140 from compounds (II). The phos-
phorylated guanidines (II) also presented a characteristic α-cleavage,
eliminating one ammonia molecule to give a phosphorylcyanamide of
m/e = 123 (Figure 1). All the symmetric phosphorylated diamines (III)
showed the same type of fragmentation to give peaks of high intensity at
m/e = M+/2, 220 and 110. Figure 2 shows the classical fragmentations,
which lead to these components.
Compounds containing
a
di-(iso-propoxy)phosphorylguanidine
present a strong absorption peak at around 210 nm and a much
weaker peak at around 250 nm. When a solution of the metal ion is
added, the spectrum shows an increase or decrease in its absorption
intensity or the appearance of new peaks if a metal complex is formed5.
No change in the spectrum is observed if there is no complex formation.
The prepared phosphorylamines (II) and (III) present UV absorption
at 202 nm and 254 nm. The preliminary complexation studies by direct
UV titration method showed that the developed potential ligands can
selectively chelate metal ions such as Cu2+, Co2+, Cd2+, Hg2+, Pb2+
,
Fe3+, Zn2+, Ni2+ and Al3+ in a neutral solution.
We now carry out a detailed study about the behavior of the developed
ligand towards different metal ions as well as the correlation between

1212
W. O. Lin et al.
FIGURE 1 Fragmentation of dialkoxyalkyl phosphite (I) and phosphoryl-
guanidine (II).
the ligand structure and metal ions. The results should offer guideline
for the further development of new ligands and information about its
application in practical life.
FIGURE 2 Fragmentation of symmetric dialkoxyalkylphosphorylamines (III).
EXPERIMENTAL
The NMR spectra (1H, 13C, and 31P) were recorded on a Bruker AC300
spectrometer. All chemical shifts are reported with respect to TMS
or H3PO4. IR spectra were obtained on a Perkin-Elmer Model 1710

Alkoxyethoxyphosphoryl Amines
1213
spectrometer. Mass spectra were taken on a Varian MAT 8500 (70
eV) spectrometer. Melting points were taken on a Fisher-Johns melting
point apparatus without correction.
Dialkoxyalkyl Phosphite— General Procedure
Dialkoxyethanol (1.2 mol) was cooled to 5◦C and phosphorus trichloride
(0.4 mol) was added drop by drop at this temperature. After the addition,
the mixture was stirred at room temperature for two hours and then
kept under reflux for another 2 h. The excess HCl formed during the
reaction was removed by strong agitation under vacuum for two hours
to give the crude product.
Di-(2-methoxy)ethyl phosphite (Ia)
Following the general procedure, 2-methoxyethanol (45.6 g, 0.6
mol) and phosphorus trichloride (27.5 g, 0.2 mol) were used; the ob-
tained crude product was distilled at reduced pressure (125–128◦C,
1 mmHg) to give a clear transparent liquid in 60% yield. IR(cm−1):
2950; 2435(P H), 1254(P O); 1052(P O). 1H NMR (CDCl3): 3.40(s, 6H,
OCH3); 3.61(t, J = 4.80Hz, 4H, OCH2); 4.17–4.32 (m, 4H, OCH2);
6.94(d, J = 717.3Hz, 1H, P H). 13C NMR: 58.69; 64.22; 71.15. 31P NMR:
7.20. Mass Spec. 199 (M++1); 141; 83; 65; 58.
Di-(2-ethoxy)ethyl phosphite (Ib)
Following the general procedure, 2-ethoxyethanol (54.0 g, 0.6 mol)
and phosphorus trichloride (27.5 g, 0.2 mol) were used; the obtained
crude product was distilled at reduced pressure (132–134◦C, 3 mmHg)
to give a clear transparent liquid in 57% yield. IR(cm−1): 2950;
2438(P H), 1259(P ); 1127 (C O); 1054(P O). 1H NMR (CDCl3): 0.97
(t, J = 6.9Hz, 6H, CH3); 3.29(q, J = 5.8Hz, 4H, OCH2); 3.41(t, J
= 6.90Hz, 4H, OCH2); 3.93–4.04 (m, 4H, P OCH2); 6.71(d, J =
736.3Hz, 1H, P H). 13C NMR: 58.69; 64.22; 71.15. 31P NMR: 5.41. Mass
Spec.: 227 (M++1); 155; 109; 83; 72; 65; 59.
Di-(2-butoxy)ethyl phosphite (Ic)
Following the general procedure, 2-butoxyethanol (70.8 g, 0.6 mol)
and phosphorus trichloride (27.5 g, 0.2 mol) were used; the obtained
crude product was distilled at reduced pressure (158–161◦C, 3 mmHg)
to give a clear transparent liquid in 35% yield. IR(cm−1): 2950;
2438(P H), 1252(P O); 1129 (C O); 1052(P O). 1H NMR (CDCl3):
0.80 (t, J = 7.2Hz, 6H, CH3); 1.21(q, J = 7.2Hz, 4H, CH2 ); 1.32–
1.59(m, 4H, CH2 ); 3.55–3.89(m, 8H, OCH2 ); 4.08–4.28 (m, 4H,
P OCH2); 6.87(d, J = 708.0Hz, 1H, P H). 13C NMR: 13.20; 19.16;

1214
W. O. Lin et al.
31.56; 61.48; 71.07; 72.00. 31P NMR: 6.98. Mass Spec.: 283(M++1); 167;
138; 111; 97; 83; 65; 57.
Di-pentyl phosphite (Id)8
Following the general procedure, n-pentanol (52.8 g, 0.6 mol) and
phosphorus trichloride (27.5 g, 0.2 mol) were used; the obtained crude
product was distilled at reduced pressure (70–71◦C, 3 mmHg) to give
a clear transparent liquid in 78% yield. IR(cm−1): 3422; 2435(P H),
1250(P O); 1127 (C O); 1056(P O). 1H NMR (CDCl3): 0.79 (t, J =
6.6Hz, 6H, CH3); 1.20–1.31 (m, 8H, CH2 ); 1.58(quin, J = 6.6Hz,
4H, CH2 ); 3.94 (t, J = 6.6Hz, 4H, P OCH2 ); 6.68 (d, J = 690Hz,
1H, P H). 13C NMR: 13.62; 21.91; 27.37; 29.88; 65.55. 31P NMR: 4.00.
Mass Spec.: 223(M++1); 153; 123; 109; 97; 83; 71; 65; 57; 43.
Phosphorylation of Amines—General Procedure
Amine (0.01 mol) and sodium hydroxide (0.02 mol) were dissolved in a
mixture of 10 ml of water and 2 ml of ethanol. This solution was cooled
to 0–5◦C, and a solution of dialkylphosphite (0.01 mol) in 10 ml of car-
bon tetrachloride was added dropwise at this temperature. The mixture
was then stirred at room temperature for 4 h; during this period, the
reaction mixture was kept basic by adding a small portion of 5% NaOH
solution. After the reaction, 10 ml each of water and chloroform (1:1)
were added. The organic layer was separated and the aqueous solu-
tion was extracted three times with chloroform (10 ml portion). The
combined organic layers were washed once with 10 ml of water and
dried over anhydrous magnesium sulfate. The solvent was removed in
a vacuum to give the crude product.
Di-(2-methoxy)ethoxyphosphorylguanidine (IIa)
Following the general procedure, guanidine hydrochloride (0.96
g, 0.01 mol) and di-(2-methoxy)ethyl phosphite (1.98 g, 0.01 mol)
were used; the obtained crude product was purified by column chro-
matography to give a light green liquid in 20% yield. IR(cm−1):
3436, 3300, 3220( NH); 2941; 2895; 1644(C N); 1371; 1245(P O);
1131(C O); 1042(P O). 1H NMR(CDCl3): 3.22; 3.24(s, 6H, O CH3);
3.43–3.47(m, 4H, O CH2 ); 3.59 (bs, 2H, NH2); 3.90–4.05(m, 4H,
CH2OP ); 6.04 (bs, 2H, NH ). 13C NMR: 58.58; 64.75; 71.12;
159.95(C N). 31P NMR: 8.68. Mass Spec. 256 (M++1); 198; 140; 123;
59; 43.
Di-(2-ethoxy)ethoxyphosphorylguanidine (IIb)
Following the general procedure, guanidine hydrochloride (0.96 g,
0.01 mol) and di-(2-ethoxy)ethyl phosphite (2.26 g, 0.01 mol) were used;

Alkoxyethoxyphosphoryl Amines
1215
the crude product obtained was purified by column chromatography us-
ing mixture of hexane and chloroform as elution solvent to give a light
green liquid, in 17% yield. IR(cm−1): 3435, 3300, 3220( NH); 2976;
2872; 1651(C N); 1575; 1371; 1242(P O); 1125(C O); 1042(P O).
1H NMR(CDCl3): 1.05–1.14(m,6H, CH3); 3.41–3.61(m, 10H, O CH2
,
NH2); 3.95–4.07(m, 4H, PO CH2 ); 6.09(bs, 2H, NH ). 13C NMR:
15.00; 64.07; 66.71; 69.13; 159.80(C N). 31P NMR: 8.42. Mass Spec. 284
(M++1); 212; 168; 140; 123; 59; 43.
Di-(2-butoxy)ethoxyphosphorylguanidine (IIc)
Following the general procedure, guanidine hydrochloride (0.96 g,
0.01 mol) and di-(2-butoxy)ethyl phosphite (2.80 g, 0.01 mol) were used;
the crude product obtained was purified by column chromatography
using mixture of hexane and chloroform as an elution solvent to give
a light green liquid, in 85% yield. IR(cm−1): 3445; 3354, 3213( NH);
2959; 2872; 1651(C N); 1578; 1465; 1363; 1242(P O); 1128(C O);
1045(P O). 1H NMR(CDCl3): 0.88–0.96(m,6H, CH3); 1.25–1.69(m, 8H,
CH2 ); 2.20 (bs, 2H, NH2); 3.40–3.65 (m, 8H, CH2O ); 4.00–
4.27(m, 4H, PO CH2 ); 5.98(bs, 2H, NH ). 13C NMR: 14.00; 20.00;
32.00; 62.00; 65.00; 70.00; 160.00(C N). 31P NMR: 8.66. Mass Spec.
340(M++1); 282; 240; 168; 140; 123; 57.
Dipentoxyphosphorylguanidine (IId)
Following the general procedure, guanidine hydrochloride (0.96 g,
0.01 mol) and dipenthl phosphite (2.24 g, 0.01 mol) were used; the crude
product obtained was re-crystallized from toluene, m.p. 72–74◦C, in 46%
yield. IR (KBr plate): 3434, 3300, 3250( NH); 3000; 2950; 1652(C N),
1241(P O); 1145(C O); 1043(P O). 1H NMR(CDCl3): 0.87–0.92(m, 6H,
CH3); 1.29–1.36(m, 8H, CH2 ); 1.60–1.69(m, 4H, CH2 ); 3.87–
3.97(m, 4H, CH2O ) 6.00(bs, 4H, NH2, NH ). 13C NMR: 13.84;
22.14; 27.61; 29.99; 65.93; 159.55(C N). 31P NMR: 6.80. Mass Spec.
280 (M++1); 210; 168; 140; 123; 43.
N,N’-Bis-(di-2-methoxyethoxy)phosphoryl
ethylenediamine (IIIa)
Following the general procedure, ethylenediamine (0.6 g, 0,01 mol)
and di-(2-methoxy)ethyl phosphite (4.00 g, 0.02 mol) were used; the
crude product obtained was purified by column chromatography using
a mixture of hexane and chloroform as the elution solvent to give a
light green liquid, in 70% yield. IR(cm−1): 3401( NH); 3300; 2943; 2890;
1
1455; 1237(P O); 1131(C O); 1040(P O). H NMR (CDCl3): 2.90(bs,
4H, NCH2); 3.25(s, 12H, OCH3); 3.46–3.48(m, 8H, OCH2 ); 3.92–
4.04(m, 8H, CH2O P). 13C NMR: 42.45; 58.79; 65.22; 71.45. 31P NMR:

1216
W. O. Lin et al.
11.40. Mass Spec.: 453 (M++1); 226; 220; 214; 197; 170; 152; 139; 110;
59; 45.
N,N’-Bis-(di-2-ethoxyethoxy)phosphoryl
ethylenediamine (IIIb)
Following the general procedure, ethylenediamine (0.6 g, 0,01 mol)
and di-(2-ethoxy)ethyl phosphite (4.55 g, 0.02 mol) were used; the crude
product obtained was purified by column chromatography using a mix-
ture of hexane and chloroform as the elution solvent to give a light
green liquid, in 39% yield. IR(cm−1): 3370( NH); 3300; 2975; 2872;
1653; 1234(P O); 1123(C O); 1038(P O). 1H NMR (CDCl3): 1.21(t, J =
7.20Hz, 12H); 2.15(bs, 2H, NH ); 3.03–3.09 (bs, 4H, NCH2 ); 3.54(q,
J = 7.20Hz, 8H, OCH2 ); 3.62(t, J=7.20Hz, 8H, OCH2 ); 4.05–
4.18(m, 8H, CH2O P). 13C NMR: 14.99; 42.37; 62.37; 65.39; 69.38.
31P NMR: 11.65. Mass Spec.: 509 (M++1); 254; 225; 221; 220; 197; 184;
153; 125; 110; 73; 45.
N, N’-Bis-(di-2-butoxyethoxyl)phosphoryl
ethylenediamine (IIIc)
Following the general procedure, ethylenediamine (0.6 g, 0,01 mol)
and di-(2-butoxy)ethyl phosphite (5.60 g, 0.02 mol) were used; the crude
product obtained was purified by column chromatography using a the
mixture of hexane and chloroform as elution solvent to give a light
green liquid, in 50% yield. IR(cm−1): 3276( NH); 2959; 2890; 1653;
1
1459; 1234(P O); 1130(C O); 1051(P O). H NMR (CDCl3): 0.91 (t,
J = 7.2Hz, 12H, CH3); 1.25–1.58 (m, 16H, CH2 ); 3.02–3.08(bs,
4H, NCH2 ); 3.47–3.60(bs, 6.9Hz, 16H, OCH2 ); 4.09–4.16(m, 8H,
POCH2 ). 13C NMR: 13.86; 19.18; 31.61; 41.53; 42.38; 61.57; 65.41;
69.51; 69.57; 71.09; 71.86. 31P NMR: 11.27. Mass Spec. 311 (M+/2 + 1);
310; 227; 220; 210; 153; 125; 110; 99; 85; 57; 45.
N,N’-Bis-(dipentoxy)phosphoryl etilenediamine (IIId)
Following the general procedure, ethylenediamine (0.6 g, 0.01 mol)
and dipentyl phosphite (4.50 g, 0.02 mol) were used; the crude product
obtained was purified by column chromatography using a mixture of
hexane and chloroform as the elution solvent to give a red liquid, in 30%
yield. IR(cm−1): 3244( NH); 2957; 2869; 1463; 1231(P O); 1118(C O);
1
1048(P O). H NMR (CDCl3): 0.85–0.94(m, 12H, CH3); 1.31–1.40(m,
8H, CH2 ); 1.60–1.68(m, 16H, CH2 ); 2.99–3.02(s, 4H, N CH2 );
3.90–4.03(m, 8H, CH2 O). 13C NMR: 13.92; 22.23; 27.70; 30.00; 42.71;
64.82. 31P NMR: 10.75. Mass Spec. 501(M++1); 500 (M+); 431; 361; 251;
250; 221; 194; 111; 110.

Alkoxyethoxyphosphoryl Amines
1217
N,N’-Di-(2-ethoxyethoxy)phosphoryl- N,N’-dimethyl
ethylenediamine (IV)
Following the general procedure, N,N’-dimethyl ethylenediamine
(0.88 g, 0.01 mol) and di-(2-ethoxy)ethyl phosphite (4.56 g, 0.02 mol)
were used; the obtained crude product was purified by column chro-
matography using a mixture of hexane and chloroform as the elution
solvent to give a liquid, in 39% yield. IR(cm−1): 3411; 2975; 2870; 1654;
1457; 1235(P O); 1126(C O); 1041(P O). 1H NMR (CDCl3): 1,21(t,
J = 6.90Hz, 6H, CH3); 2.21 (s, 6H, NCH3); 2.38(t, J = 6.30Hz,
2H, NCH2 ); 2.98–3.05(m, 2H, PNCH2 ); 3.54(q, J = 6.90Hz, 4H,
OCH2 ); 3.62–3.66(m, 4H, OCH2 ); 4.10–4.20(m, 4H, POCH2 ).
13C NMR: 14.97; 38.30; 44.87; 59.46; 66.43; 65.32; 69.33. 31P NMR:
11.20. Mass Spec. 313(M++1); 312 (M+); 240; 168; 110; 58.
Complexation Studies by UV Spectroscopy
Inorganic salts were used as purchased and kept under nitrogen in a
desiccator. The ligand solutions in anhydrous methanol were prepared
by diluting a 0.1 M stock solution to the expected suitable concentration.
For the differential spectra, an inorganic salt solution was placed in the
reference cell. Metal ion solutions were prepared in 0.01 M, 0.1 M, and
1.0 M concentrations; these solutions were added to the ligand solution
through a 10 µl GC syringe, so that the changes in volume could be
neglected. After each addition, the cell was thoroughly shaken before
the UV spectrum was recorded. For the qualitative studies, a 10-fold
excess of the salts was used.
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