Unconventional reactivity of epichlorohydrin in the presence of triphenylphosphine: isolation of ((1,4-dioxane-2,5-diyl)-bis-(methylene))-bis-(triphenylphosphonium) chloride

Article abstract of DOI:10.1007/s11164-020-04364-9

The selective formation of the heterocyclic salt ((1,4-dioxane-2,5-diyl)-bis-(methylene))-bis-(triphenylphosphonium) chloride was observed when epichlorohydrin and triphenylphosphine were reacted in CH₂Cl₂ at room temperature. Slow evaporation from a mixture of ethanol and ethyl acetate allows to isolate monocrystals of the heterocyclic phosphonium salt. Mechanistic investigations point to the formation of the zwitterionic intermediate 1-chloro-3-(triphenylphosphonio)-propan-2-olate, which can dimerize and generate the 1,4-dioxane derivative. In the exclusive presence of a Br?nsted acid as HCl, which usually facilitates epoxide ring opening, the exclusive formation of 1,3-dichloro-2-propanol was although observed. Also, when epichlorohydrin, PPh₃, and a stoichiometric amount of HCl were mixed, (2-chloro-3-hydroxypropyl)-triphenylphosphonium chloride was formed and its isolation in pure form provides monocrystals subjectable to X-ray analysis.

Full text of DOI:10.1007/s11164-020-04364-9

Research on Chemical Intermediates (2021) 47:1663–1674
https://doi.org/10.1007/s11164-020-04364-9
Unconventional reactivity of epichlorohydrin
in the presence of triphenylphosphine: isolation of ((1,4‑
dioxane‑2,5‑diyl)‑bis‑(methylene))‑bis‑
(triphenylphosphonium) chloride
Alberto Mannu1,2 · Maria Enrica Di Pietro · Emanuele Priola ·
1
2
2
1
1,3
Salvatore Baldino · Alessandro Sacchetti · Andrea Mele
Received: 15 October 2020 / Accepted: 11 December 2020 / Published online: 22 January 2021
The Author(s), under exclusive licence to Springer Nature B.V. part of Springer Nature 2021
©
Abstract
The selective formation of the heterocyclic salt ((1,4-dioxane-2,5-diyl)-bis-
(
methylene))-bis-(triphenylphosphonium) chloride was observed when epichloro-
hydrin and triphenylphosphine were reacted in CH Cl at room temperature. Slow
2
2
evaporation from a mixture of ethanol and ethyl acetate allows to isolate monocrys-
tals of the heterocyclic phosphonium salt. Mechanistic investigations point to the
formation of the zwitterionic intermediate 1-chloro-3-(triphenylphosphonio)-pro-
pan-2-olate, which can dimerize and generate the 1,4-dioxane derivative. In the
exclusive presence of a Brønsted acid as HCl, which usually facilitates epoxide ring
opening, the exclusive formation of 1,3-dichloro-2-propanol was although observed.
Also, when epichlorohydrin, PPh , and a stoichiometric amount of HCl were mixed,
3
(
2-chloro-3-hydroxypropyl)-triphenylphosphonium chloride was formed and its iso-
lation in pure form provides monocrystals subjectable to X-ray analysis.
Keywords Epichlorohydrin · Triphenylphosphine · Zwitterion · Phosphonium ·
Dioxane
*
Alberto Mannu
alberto.mannu@unito.it
1
Department of Chemistry, Materials and Chemical Engineering “G. Natta”, Politecnico di
Milano, Piazza L. da Vinci 32, 20133 Milan, Italy
2
3
Dipartimento di Chimica, Università di Torino, Via Pietro Giuria, 7, 10125 Turin, Italy
CNR-ICRM Istituto di Chimica del Riconoscimento Molecolare, “U.O.S. Milano Politecnico”,
Via L. Mancinelli, 7, 20131 Milan, Italy
Vol.:(012
1
3456789)
3

1664
A. Mannu et al.
Introduction
Epichlorohydrin represents a versatile building block for many organic transfor-
mations. The possibility to obtain epichlorohydrin from glycerol derived from
biomass or generated as waste by-product from other processes represents an
important industrial route of such building block [1]. The large number of syn-
thetic possibilities oꢀered by this substrate is due to the presence of three diꢀer-
ent electrophilic centers (endocyclic CH and CH, exocyclic CH –Cl) and one
2
2
nucleophilic atom (oxygen). In addition, the reactivity of the epichlorohydrin is
enhanced by the high energy content of the three-member oxirane ring, which
presents a ring strain energy of 117 kJ/mol [2].
Also, epichlorohydrin is the substrate of choice when the ring-opening process
on the endocyclic CH is the desired pathway. In fact, the parent epibromohydrin
2
is usually less selective, giving rise to a mixture of products derived from the
nucleophilic attack both on the endocyclic-CH and exocyclic CH –Br moieties
2
2
[
3, 4].
During the last decades, the behavior of several nucleophiles as amines, alkali
amides [5], thioethers, phosphorus ylides in the presence of epichlorohydrin-
based compounds [2] or generally in the presence of oxiranes has been studied.
Many researchers have also achieved the possibility to perform the ring open-
ing of epihalohydrins (Cl, Br) in enantioselective fashion by employing oppor-
tune chiral catalysts [6, 7] or by exploiting enantio-enriching processes [8]. Very
recently, ring opening and subsequent cyclodimerization of epichlorohydrin pro-
moted by imidazolate Metal Organic Frameworks (MOFs) to obtain 1,4 dioxane-
2
,5-bis-chloromethyl in good yields (up to 70%) were reported by Mousavi et al.
[
9, 10].
Nevertheless, the selective ring-opening process of epichlorohydrin is not an
easy target to be attained, also due to the presence of the highly electrophilic
CH –Cl functionality. As a matter of fact, the employment of a Lewis or Brønsted
2
acids seems to be required in most cases for achieving an eꢁcient ring-opening
process, whereas the competitive S 2 reaction on the exocyclic CH –Cl moiety
N
2
is favored by a neutral or basic environment [11]. It is worth pointing out that,
despite the large number of articles on the subject [2], the reactivity of epichlo-
rohydrin with some nucleophiles is still unclear. In particular, poor attention has
been given to nucleophilic species bearing soft nucleophilic atoms, such as the
phosphorus. Among P(III)-based reagents, only one report dating back to 1959
describes the reaction between epichlorohydrin and triphenylphosphine (PPh ) in
3
the absence of acidic mediators, claiming to obtain a corresponding phosphonium
salt [12]. However, the description of the reaction conditions was not clear and
no characterization was presented. Given the great availability and versatility of
phosphane compounds and intrigued by this lack of information, we thought that
this topic deserved a deeper investigation and understanding. For such reasons,
PPh was herein employed as model nucleophile.
3
Thus, in the present research paper, the unconventional reactivity between
epichlorohydrin and PPh to form ((1,4-dioxane-2,5-diyl)-bis-(methylene))-bis-
3
1
3

Unconventional reactivity of epichlorohydrin in the presence…
1665
(
triphenylphosphonium) chloride (1) is described for the ꢂrst time. The exploration
of the reaction conditions, including its outcome in the presence of HCl, allowed
to propose a reaction mechanism which involves the generation of the zwitterionic
intermediate 1-chloro-3-(triphenylphosphonio)-propan-2-olate (I). Such intermedi-
ate can, in the presence of HCl, selectively bring to the formation of (2-chloro-
3
-hydroxypropyl)-triphenylphosphonium chloride (2), herein described and charac-
terized for the ꢂrst time. For both the novel products, characterizations in solution
by NMR and in solid state by X-ray crystallography are reported.
Results
During some reactivity tests on epichlorohydrin, we observed that triphenylphos-
phine was able to slowly react at room temperature and to form an unknown species,
with low solubility in organic solvents, which appears as singlet at 24.5 ppm when
3
1
observed by decoupled P NMR (CDCl ). Although the reaction was slow at room
3
temperature, resulting in a conversion of less than 10% after 1 week, by suitable
work-up [13], it was possible to isolate some crystals of the product. Characteri-
1
13
31
zation of such crystals in solution by H, C and P NMR revealed the selective
formation of the heterocyclic trans-((1,4-dioxane-2,5-diyl)-bis-(methylene))-bis-
(
triphenylphosphonium) chloride (1), (Scheme 1; Fig. 1).
For trans-1,4-disubstituted six-member rings, the conformation with both groups
adopting equatorial positions is much more stable with respect to the sterically hin-
dered axial disposition. This makes it possible to distinguish the axial and equato-
rial protons for the endocyclic CH group, respectively, at 3.19 ppm, characterized
2
by the geminal coupling and the vicinal trans coupling, and at 4.38 ppm, showing
the geminal coupling. Two diꢀerent signals are also observed for the exocyclic CH
2
group next to the triphenylphosphonium moiety, a pseudo-triplet at 5.25 ppm and a
1
1
1
31
doublet of triplets at 3.08 ppm, characterized by both H- H and H- P scalar cou-
pling constants. Such big diꢀerence in chemical shift for geminal protons of –CH
2
moiety next to phosphorus has been observed, for example, in other alkyl-phos-
phine-boranes with similar structural motif [14, 15]. The CH group gives the broad
multiplet at 3.66 ppm. Finally, the aromatic protons of the triphenyl groups appear
as usual between 7.6 and 7.8 ppm (Fig. 1).
Single crystals of 1 were obtained by slow evaporation from a mixture of EtOH/
Hexane. Solid-state characterization of 1 by single crystal X-ray crystallography
conꢂrmed the molecular structure observed in solution (Fig. 2).
Scheme 1 Synthesis of 1,4-dioxane 1 by reaction between PPh and epichlorohydrin
3
1
3

1666
A. Mannu et al.
1
13
Fig. 1 H- C HSQC NMR of 1 in CDCl
3
Fig. 2 X-ray single crystal molecular structure of 1 (a) representation of the substituent disposition
around the trans-1,4-disubstituted six-member ring (b) and unit cell along [010] axis (c) (ellipsoid prob-
ability: 50%). (Color code: gray, carbon; orange, phosphorous; red, oxygen; green, chloride)
1
3

Unconventional reactivity of epichlorohydrin in the presence…
1667
Compound 1 crystallizes in C2/c monoclinic space group with a halved molecule
around an inversion center in the asymmetric unit (Fig. 1a for the complete mol-
ecule). The molecule possesses the conformation with both phosphonium groups
adopting equatorial positions, conꢂrming the NMR results (Fig. 1b). The dicationic
molecule is surrounded by cavities in which disordered chlorides and water mol-
ecules are disposed (Fig. 2c). At low temperature (200 K), the two nonequivalent
sites have been more precisely characterized with a composition of 0.5 Cl and 0.5
H O, while at ambient temperature these cavities are ꢂlled with an undiꢀerentiated
2
electron density of the two species. By considering the dependence of the crystal
cell parameters with the temperature, it is worth mentioning that a lattice constant is
−
4
more dependent on temperature with respect to the other two (d(a)/dT=9.95×10
−4
−4
respect to d(b)/dT=8.3×10 , d(c)/dT=3.7×10 , while, considering the mono-
−
3
clinic variable beta angle, the dependence is d(β)/dT=2.55×10 ), probably for the
compression of the cations and the subsequent ordering of the water/chloride spe-
cies into the cavities.
It is worth pointing that the formation of 1 from a mixture of PPh and epichloro-
3
hydrin at room temperature in CH Cl is unexpected and, to the best of our knowl-
2
2
edge, never described before.
In general, it is known that 1,4-dioxane derivatives can be formed by treating the
corresponding epoxides with Lewis acids. In a report dating back to 1959, the for-
mation of the cyclic dimer 2,5-diphenyl-1,4-dioxane as byproduct of the cationic
polymerization of styrene epoxide catalyzed by with AlCl , SbCl , BeCl , FeCl ,
3
5
2
3
SnCl , TiCl , ZnCl , or ZrCl has been postulated on the basis of mass spectrometry
4
2
2
4
evidences, but never proven [16]. The supposed dioxane derivative was described
as undesired byproduct produced from an unknown pathway which consumes up to
1
0% of the starting materials, resulting in a not negligible drop of yield and qual-
ity of the desired polymer. Later, the dimerization to epihalohydrines in the pres-
ence of a cobalt-bases catalyst to give 1,4-dioxane derivatives was described in 1964
by McClure [17], while recently, Mousavi and coworkers reported the synthesis of
the 1,4 dioxane-2,5-bis-chloromethyl by employing some MOFs as Lewis acids [9].
The reaction mechanism proposed by the Authors was based on the known cationic
polymerization of epoxides in the presence of Lewis acids. A characteristic aspect of
such reaction is the ring opening, which produces a secondary carbocation with an
alcoholic function in α position [18, 19].
Moreover, ring opening of epoxides in the presence of Brønsted acids usually fol-
lows a diꢀerent pathway, as it is the consequence of a nucleophilic substitution of
second order (S 2) by the halide on the endocyclic CH , with the formation of a sec-
N
2
ondary alcohol. Speciꢂc examples of such reactivity between epichlorohydrin and
HCl or HBr are known and have been exploited for the synthesis of 1,3-halochloro-
2
-propanol [20]. The same reaction was described by Torabi and coworkers employ-
ing as trihalide nucleophiles (triiodine and tribromide anion) generated in situ in the
presence of the catalyst meso-tetraphenylporphyrins (H TPP) [21].
2
Such outcome was conꢂrmed even in the presence of PPh : when we added to a
3
CH Cl solution of epichlorohydrin 1 eq. of PPh and a large excess (>10 eq.) of
2
2
3
HCl (37%), after work-up, a mixture of 1,3-dichloro-2-propanol and unreacted PPh
was quantitatively recovered.
3
1
3

1668
A. Mannu et al.
The nucleophilic attack of PPh on the former chloro-alcohol was not observed at
3
room temperature neither after 72 h.
On the other side, when the same reaction was repeated with 1 eq. of HCl, the
intermediate salt (2-chloro-3-hydroxypropyl)-triphenylphosphonium-chloride (2)
was isolated in form of white crystals. Formally, product 2 can result from two dif-
ferent pathway, as reported in Scheme 2.
Following the ꢂrst pathway, the nucleophilic attack of PPh on the epichlorohy-
3
drin ring generates the zwitterionic alkoxide 1-chloro-3-(triphenylphosphonio)-pro-
pan-2-olate (I), which can be trapped as (3-chloro-2-hydroxypropyl)-triphenylphos-
phonium chloride after addition of HCl (2). In the second route, the epichlorohydrin
is protonated by HCl and subsequently attacked by PPh . In this last proposal, no
3
zwitterionic intermediate is postulated [22, 23].
It is worth noticing that the reaction reported in Scheme 2 occurred with complete
regio- and chemoselectivity as already observed by Mironov and coworkers for tri-
phenylphosphonium triꢃuoromethanesulfonates with epoxide derivatives [24]. The
same reaction was already described by Schweizer et al. in the case of 1,2-epoxy-
3
-(2-formylphenoxy)-propane and triphenylphosphine hydrobromide [25]. Similar
ring-opening examples were reported by Wang and coworkers, who described the
hydrolysis of epichlorohydrin, styrene oxide, aziridines and other epoxides in hot
water [26].
By dissolving 2 in a mixture of EtOH/AcOEt, it was possible by slow evapora-
tion to isolate some white crystals suitable for X-ray crystallographic analysis. The
molecular structure of 2 is reported in Fig. 3a.
Compound 2 crystallizes in monoclinic C2/c space group, with an asymmetric
unit composed of a 2 molecule, a chloride ion and a water molecule that interact
with the alcoholic group through OH⋯O hydrogen bond (d(O1⋯O1)=2.818(5)
Å at T=200 K, 2.821(6) at T=299 K, ang(C2–O1–O2)=102.83(7)° at
T=200 K, 103.60(9)° at T=299 K, see Fig. 3a). The structural ordered water is
involved in the formation of a dimeric structure in which both the water hydro-
gens interact with the chlorides (d(O2⋯Cl1)=3.102(4)Å at T=200 K, 3.105(6)
at T=299 K, ang(O1–O2–Cl1)=110.28(6)° at T=200 K, 134.11(9)° at
T=299 K, ang(Cl1–O2–Cl1)=98.85(7)° at T=200 K, 99.22(9)° at T=299 K,
ang(O2–Cl1–O2)=81.15(5)° at T=200 K, 80.78(9)° at T=299 K, see Fig. 3a)
Scheme 2 Nucleophilic ring opening of epichlorohydrin in the presence of PPh to obtain 2
3
1
3

Unconventional reactivity of epichlorohydrin in the presence…
1669
Fig. 3 Molecular structure of (3-chloro-2-hydroxypropyl)-triphenylphosphonium-chloride 2(a), sestuple
phenyl embrace motif (b) and hydrogen bonded dimers of Cl-H O and 2 (c) (ellipsoid probability: 50%.)
2
(
Color code: gray, carbon; orange, phosphorous; red, oxygen; green, chloride)
forming a lozenge of hydrogen bonds. As can be seen, all the distances and almost
all the angles are poorly aꢀected by temperature; the most changing parameter is the
O1–O2–Cl1 angle, promoting the formation at low temperature of an array of weak
C–H⋯Cl interaction both with the aromatic and the aliphatic parts of 2. The ꢂnd-
ings that all the distances associated with the weak interactions and in the overall
molecular conformation are virtually constant explain the weak distortion of the lat-
tice parameters with temperature. Finally, the interaction between the triphenylphos-
phonium fragments through the typical sestuple phenyl embrace motif is a stabiliz-
ing pattern composed of a multitude of optimized C–H⋯π and π⋯π interactions (see
Fig. 3b) [27, 28].
In principle, there is no way to discern between the two pathways reported in
Scheme 2 without isolate or observe one of the two characteristic intermediate spe-
cies. Nevertheless, the formation of the 1,4 dioxane derivative points to the forma-
tion of the zwitterionic intermediate I (Scheme 3), which well ꢂts as precursor for 1
(
Scheme 3).
Scheme 3 can be resumed as follows: ring opening of epichlorohydrin by nucle-
ophilic attack of PPh on the endocyclic –CH generates a zwitterionic species I,
3
2
which, in the absence of acids or electrophiles, undergoes cyclic dimerization to
+
form 1,4-dioxane derivative 1. Any source of H , as Brønsted acids, brings to a
deactivation pathway by quenching the zwitterionic reactive intermediate. At this
regard, the stability of intermediate I and similar compounds generated by reaction
1
3

1670
A. Mannu et al.
Scheme 3 Proposed mechanism for the synthesis of 2 from epichlorohydrin and PPh3
of epichlorohydrin and diꢀerent nucleophiles is currently under investigation. In
particular, at moment, it is not possible to discard the formation of an oxaphos-
phoethane [29], which would stabilize I for long enough time to allow the slow
dimerization.
In order to extend the study of the reaction at diꢀerent conditions, reꢃux-
ing CH Cl and CH CN were also employed as solvents. In both cases,
2
2
3
1
,3-bis(triphenylphosphonio)propan-2-olate 3, which arises from a nucleophilic sub-
1
stitution of PPh on the CH –Cl moiety of I, was observed by H NMR (Scheme 4).
3
2
The reaction reported in Scheme 4 represents the second possible deactiva-
tion pathway encountered on the way of the formation of trans-((1,4-dioxane-
2
,5-diyl)-bis-(methylene))-bis-(triphenylphosphonium)-chloride (1) from PPh and
3
epichlorohydrin.
The detrimental eꢀect of high temperatures on the dimerization rules out the pos-
sibility of increasing thermodynamically the conversion of the reaction.
A summary of the outcome observed in diꢀerent reaction conditions is reported
in Table 1.
The data reported in Table 1 show that the soft nucleophile PPh is not eꢁcient
3
in promoting the nucleophilic ring opening of epichlorohydrin. The dimerization
reaction to give product 1 takes place slowly, at room temperature and preferably
Scheme 4 Synthesis of 1,3-bis(triphenylphosphonio)propan-2-olate 3
1
3

Unconventional reactivity of epichlorohydrin in the presence…
1671
Table 1 Reactivity between epichlorohydrin and PPh3
Entry Nucleophile Solvent
Main product after workup
Conversion
a
(
%)
1
2
3
–
–
PPh3
HCl 37%
CH Cl
1,3-Dichloro-2-propanol
Starting materials
Quantitative
2
2
2
CH Cl
((1,4-dioxane-2,5-diyl)-bis-(methylene))-bis-
8.0%
2
(
triphenylphosphonium)-chloride (1)
4
PPh3
CH Cl and
Starting materials
2
2
Cs CO
2
3
5
6
7
8
PPh3
PPh3
PPh3
PPh3
Cl CH CH Cl Starting materials
2
2
2
2
CH CN
THF 50 °C
Starting materials
Starting materials
3
b
CH Cl , HCl
(3-Chloro-2-hydroxypropyl) triphenylphosphonium 4%
2)
((1,4-Dioxane-2,5-diyl)-bis-(methylene))-bis-
triphenylphosphonium) chloride (1)
2
2
(
9
PPh3
CH CN
Traces
3
(
c
10
11
12
PPh3
PPh3
PPh3
CH Cl
1,3-Bis(triphenylphosphonio)propan-2-olate (3)
1,3-Bis(triphenylphosphonio)propan-2-olate (3)
((1,4-Dioxane-2,5-diyl)-bis-(methylene))-bis-
Traces
Traces
10%
2
2
c
CH CN
3
Neat
(
triphenylphosphonium)-chloride (1)d
a
Calculated from 31P NMR of the crude mixture
PPh and epichlorohydrin were dissolved in CH Cl and HCl was then added
Reactions performed at reꢃux
A complex mixture of species was observed. The target compound was not isolated in this case. Condi-
b
c
d
3
2
2
tions: epichlorohydrin and PPh were mixed in a 1:1 molar ratio if otherwise indicated. All the reactions
3
were performed during 5 days
in CH Cl (entry 3). The additive Cs CO seems to inhibit the reaction, leading to
2
2
2
3
a mixture of starting products even after 5 days (entry 4). From the other side, the
presence of HCl drives the reactivity of the starting materials to the formation of
product 2 (entry 8). Heating the reagents, both in CH Cl and CH CN, results in the
2
2
3
formation of product 3, with no traces of the dimer 1.
As matter of fact, the eꢀect of the CH Cl on the outcome of the reaction is piv-
2
2
otal. The nucleophilic ring opening of substituted epoxides on the endocyclic –CH
2
moiety was already described as very sensitive to the solvent employed, with an
adverse eꢀect of both THF and CH CN when hydroxide ion was used as nucleo-
3
phile [26]. On the other side, CH Cl revealed to be the solvent of choice for the
2
2
ring opening of epoxides with HBr or HCl [20], in the presence of triphenylphos-
phonium triꢃuoromethanesulfonate [24] or halides [21]. In general, CH Cl has
2
2
been employed with success in chemical transformations involving zwitterionic
intermediates, emerging as the best solvent to guarantee a survival of these inter-
mediates for a time suꢁcient for their characterization [30] or for their slow trans-
formation [31].
1
3

1672
A. Mannu et al.
Conclusions
The formation of dioxane derivative double salt 1 as result of the reaction between
epichlorohydrin and the soft nucleophile PPh takes place in CH Cl at room tem-
3
2
2
perature. This speciꢂc synthetic pathway could explain the detection of dioxane
derivatives during the known polymerization of styrene oxide, described as impuri-
ties since 1959 [12].
On the other side, the salts 2 and 3 can be obtained, respectively, from the proto-
nation of the zwitterionic intermediate I and from the subsequent nucleophilic sub-
stitution of PPh on the –CH Cl moiety of 2. In general, the presence of these prod-
3
2
ucts cannot be neglected when epichlorohydrin is used in the presence of PPh and
3
CH Cl as solvent. The structures of novel products 1 and 2 were conꢂrmed in solid
2
2
state by X-ray analysis, herein reported for the ꢂrst time.
Experimental part
All manipulations were carried out without using inert gases, and solvents and rea-
gents were employed as received from suppliers.
NMR analyses
NMR spectra were recorded at 11.7 T using a Bruker NEO 500 spectrometer
equipped with a 5-mm pulsed-ꢂeld z-gradient BBFO probe and a variable-temper-
ature unit and were referenced internally to the deuterated solvent. For decoupled
3
1
1
P{ H} NMR spectra, 85% H PO was used as external standard. Topspin software
3
4
(
4.0.7 version) from Bruker was used for data processing. All the NMR spectra have
been recorded at 298 K (25 °C) unless otherwise indicated.
Single-crystal data were collected with a Gemini R Ultra diꢀractometer with
graphite-monochromated Mo-Kα radiation (λ=0.71073) for (1)–(2) by the ω-scan
method. The low temperature measurements at 200 K have been collected on the
same instrument using a Cryojet apparatus. Cell parameters were retrieved with the
CrysAlisPro software, and the same program was used to perform data reduction
with corrections for Lorenz and polarizing eꢀects. Scaling and absorption correc-
tions were applied through the CrysAlisPro [CrysAlis PRO 1.171.38.46 (Rigaku
OD, 2015).] multiscan technique. The structure for 1 and 2 was solved with Direct
Methods [32]. All structures have been reꢂned with full-matrix least-squares tech-
2
niques on F with SHELXL-14 [33] using the program Olex2 [34]. All non-hydro-
gen atoms were reꢂned anisotropically. Hydrogen atoms were calculated and rid-
ing on the corresponding bonded atoms. The graphics of the crystal structure has
been generated using Mercury 3.9 [35]. CCDC codes 2019909–2019912 contain the
supplementary crystallographic data for 1 to 2. These data can be obtained free of
charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44)
1
223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
1
3

Unconventional reactivity of epichlorohydrin in the presence…
1673
Mass spectrometry
The ESI–MS experiments were performed using a Bruker Esquire 3000 PLUS (ESI
Ion Trap LC/MSn System), equipped with an ESI source and a quadrupole ion trap
detector (QIT).
Acquisition parameters: needle: 4.5 kV, N2 ꢃow rate: 10 L h-1, cone voltage:
4
0 V, Scan resolution and range: 13 000 (m/z) s-1 over the mass range m/z 35–500,
−
1
by direct infusion of methanol solution of compounds at rate: 4 µl min .
General procedure for isolation of compounds 1
((1,4‑dioxane‑2,5‑diyl)‑bis‑(methylene))‑bis‑(triphenylphosphonium)‑chloride (1)
In a round-bottomed ꢃask, to 0.01 mol. of epichlorohydrin and an equimolar amount
of triphenylphosphine, 5 mL of CH Cl was added. The mixture was stirred at room
2
2
temperature for one week. The solvent was removed under vacuum and the crude
product washed with hexane (5×3 mL) in order to remove most of the unreacted
PPh and epichlorohydrin. The residue was dissolved in a mixture of ethanol and
3
ethyl acetate (1:1 in volume). White crystals were obtained through slow evapora-
tion of the solvent.
1
H NMR (CDCl ): 2.94–3.13 ppm (m, CH –P, 1H); 3.13–3.30 (CH –C, 1H);
3
2
2
3
.58–3.83 ppm (m, CH, 1H); 4.28–4.42 ppm (m, CH –C, 1H); 5.08–5.26 ppm (m,
2
CH –P, 1H); 7.47–8.00 ppm (m, Ph, 15H).
2
3
1
1
3
P NMR (CDCl ): 24.5 (s)
3
C NMR (CDCl ): 25.7 ppm (d, 1J =53.2 Hz, CH –P); 69.9 ppm (d,
3
CP
2
2
2
3
JCP =6.0 Hz, CH); 70.6 ppm (d, JCP =19.7 Hz, CH –C); 130.1 ppm (d,
2
3
JCP =12.7 Hz, o-Ph); 133.9 ppm (d, J =10.2 Hz, m-Ph); 134.7 ppm (s, p-Ph)
CP
MS–ESI: m/z 319.1
General procedure for isolation of compounds 1
2‑chloro‑3‑hydroxypropyl)‑triphenylphosphonium‑chloride (2)
(
In a
round-bottomed ꢃask, to 0.01 mol. of epichlorohydrin and an equimolar amount
of triphenylphosphine, 5 mL of CH Cl was added. Then, 1 ml of a 1 M aqueous
2
2
solution of HCl was added. The mixture was stirred at room temperature for one
week. The solvent was removed under vacuum and the crude product washed with
hexane (5×3 mL) in order to remove most of the unreacted PPh and epichlorohy-
3
drin. The residue was dissolved in a mixture of ethanol and ethyl acetate (1:1 in vol-
ume). White crystals were obtained through slow evaporation of the solvent.
1
H NMR (DMSO-d6): 3.64–3.66 (m, CH –P, 1H); 3.66–3.69 (m, CH–OH,
2
1
H); 3.70–3.75 (m, CH–Cl, 1H); 3.82–3.90 (m, CH–Cl, 1H); 3.92–4.00 (m,
CH –P, 1H); 7.68–7.72 (m, o-Ph, 6H); 7.73–7.78 (m, m-Ph, 6H); 7.80–7.85 (m,
2
o-Ph, 3H).
1
3

1674
A. Mannu et al.
1
3
C NMR (DMSO-d6): 27.3 (s, CH –P); 66.2 (s, CH –Cl); 130.5 (d, J=12.8 Hz,
2
2
o-Ph); 134.3 (d, J=10.5 Hz, m-Ph); 135.2 (s, p-Ph).
31
PNMR (DMSO-d6): 24.8 (s)
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