Synthesis and crystal structure of (5-Ethyl-2-methyl-2-phenyl-1,3-dioxan-5-yl)methanol

Article abstract of DOI:10.14233/ajchem.2015.17763

A new compound (5-ethyl-2-methyl-2-phenyl-1,3-dioxan-5-yl)methanol, obtained from the reaction of 2,2-bis(hydroxymethyl)butanol with acetophenone, has been synthesized and characterized by IR and ¹H NMR. Single crystal X-ray diffraction analyse

Full text of DOI:10.14233/ajchem.2015.17763

Asian Journal of Chemistry; Vol. 27, No. 6 (2015), 2099-2101
A
SIAN
J
OURNAL OF HEMISTRY
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http://dx.doi.org/10.14233/ajchem.2015.17763
Synthesis and Crystal Structure of (5-Ethyl-2-methyl-2-phenyl-1,3-dioxan-5-yl)methanol
1,*
1
1,2
1
XIAN-YOU YUAN , XIN-YU ZHANG , GUANG-CHUAN OU , LIN YUAN1,2 and MIN ZHANG
1Department of Biology and Chemistry, Hunan University of Science and Engineering, Yongzhou, Hunan, P.R. China
2Key Laboratory of Functional Organometallic Materials of Hunan Province College, Hengyang Normal University, Hengyang, Hunan, P.R. China
*Corresponding author: Tel: +86 746 6381164, E-mail: yuanxianzhangmin@163.com
Received: 4 April 2014;
Accepted: 5 June 2014;
Published online: 17 March 2015;
AJC-16970
A new compound (5-ethyl-2-methyl-2-phenyl-1,3-dioxan-5-yl)methanol, obtained from the reaction of 2,2-bis(hydroxymethyl)butanol
with acetophenone, has been synthesized and characterized by IR and 1H NMR. Single crystal X-ray diffraction analyses indicated that
the title compound belongs to tetragonal system with space group I4(1)/a with a = 29.921(2) Å, b = 29.921(2) Å, c = 5.9627(9) Å. Mr
= 236.30, V = 5338.1(10) Å3, Dc = 1.176 g/cm3, Z = 16, µ = 0.081 mm-1, F(000) = 2048, R = 0.0595, wR = 0.1645. In the title compound,
the 1,3-dioxane ring adopts a chair conformation and the phenyl substituent occupies an equatorial site. In the crystal, adjacent four
molecules are connected by O-H···O hydrogen bonding interactions into a tetramer.
Keywords: 1,3-Dioxane, Acetophenone, Synthesis, Crystal structure.
Chemical Plant. 2,2-bis(Hydroxymethyl)butanol was the
product of Aladin. Crystal structure was determined on a
Bruker SmartApex II diffractometer. Elemental analyses were
performed by direct combustion with a PE2400 instrument.
The IR spectra were recorded in the 4000-400 cm-1 region
using KBr pellets and a Niconet AVATAR-360 spectrometer.
1H NMR spectra were recorded in a CDCl3 solution with a
BrukerAV-400 spectrometer. Melting point data were recorded
in a Buchi B545 spectrometer.
Synthesis of (5-ethyl-2-methyl-2-phenyl-1,3-dioxan-5-
yl)methanol: 2,2-bis(Hydroxymethyl) butanol (1.3400 g, 10
mmol) and acetophenone (1.3215 g, 11 mmol) were added
into 50 mL round-bottom flask provided with a stirrer and a
reflux condenser. Both a solution of N,N-dimethylformamide
(5 mL), cyclohexane (8 mL) and 1-acetyl-3-methylimidazole
hydrogen sulfate (0.1 g) were simultaneously added dropwise
to the flask and the reacting solution was kept at 378 K under
reflux for 4 h. After the reaction completion, the reaction
mixture was poured into separator funnel and separated. The
organic layer was washed with water (10 × 3 mL), dried with
MgSO4. Once more filtered and evaporated to dryness. Then
the white solid powder was obtained 1.3 g (yield: 53 %). The
melting point of purified product was 357.3-358.1 K. The
product was recrystallized from cyclohexane to afford
colourless crystals (Scheme-I). Anal. Calcd. for C14H20O3: C,
INTRODUCTION
Acetal compounds have many characters such as aroma1
and chemical stability2, which are used widely in fragrances
and food flavors3,4. Acetal compounds are stable in neutral
and alkaline conditions and will degradate and generate a
material of small molecules in acidic conditions. Polyfunc-
tional branched compounds are the new class of compounds
with a wide range of applications.The synthesis of these
compounds rich in raw materials and simple manufacturing
process, in the synthesis of fine chemicals and other industries
have shown important uses and has great potential for deve-
lopment5-7. Ionic liquids as a catalyst have especial advantages
in the synthesis of acetal compounds in 21st century green8.
To our knowledge the report of 2,2-dimethylolbutyric acetal
(ketone) was rare. Herein, in this paper, a novel compounds
(5-ethyl-2-methyl-2-phenyl-1,3-dioxan-5-yl)methanol was
synthesized by using 2,2 -bis(hydroxymethyl) butanol with
acetophenone as raw material, ionic liquid as catalyst, DMF
and cyclohexane as solvent and its structure has been charac-
terized.
EXPERIMENTAL
The ionic liquid of 1-acetyl-3-methylimidazole hydrogen
sulfate was prepared according to the literature method9. All
the starting materials and solvents were commercially available
and used without further purification. acetophenone and ethyl
acetate were obtained commercially from Tianjin Damao
71.19; H, 8.47 %. Found C, 71.10; H, 8.29 %. IR (KBr, νmax
,
cm-1): 3327, 2954, 2870, 1461, 1377, 1242, 1087, 1021, 878,
767, 703.

2100 Yuan et al.
Asian J. Chem.
OH
TABLE-1
CRYSTAL DATA AND STRUCTURE
REFINEMENT FOR THE TITLE COMPOUND
O
DMF+
O
HO
+
O
ionic liquid
CH2OH
OH
Parameter
Empirical formula
Formula weight
Crystal size (nm)
Crystal system, space group
a, b, c (Å)
Compound
C14H20O3
236.30
Scheme-I
1H NMR (CDCl3, 400 MHz) δ(ppm): 7.314-7.413 (5H,
m, ArH); 3.970-3.982 (2H, d, J = 4.8 Hz, CH2-OH); 3.683-
3.712 (2H, d, J = 11.6 Hz, 2CO-CH2-C, Heq); 3.443-3.472
(2H, d, J = 11.6 Hz, 2CO-CH2-C, Hax); 1.645(1H, s, -OH);
1.510 (3H, s, CH3-C); 1.002-1.040 (2H, q, J = 7.6Hz, C-CH2-
CH3); 0.726-0.888 (3H, t, J = 7.6 Hz, CH3-CH2).
0.46 × 0.42 × 0.36
Tetragonal, I4(1)/a
29.921(2), 29.921(2), 5.9629 (9)
α = 90, β = 90, γ = 90
5338.1(10)
α, β, γ (°)
V/Å3
Dc/mg cm–3
µ/mm–1
F(000)
Z
1.176, 16
0.081
2048
X-ray crystal structure determination: A colourless
block crystal with dimensions of 0.46 mm × 0.42 mm × 0.36
mm was selected for measurement. Diffraction data of
compound were collected at 296(2) K on a Bruker Smart CCD
area detector, with MoKα radiation (λ = 0.71073 Å). A total
of 21212 reflections were collected in the range of 1.36 to
27.34º by using an φ-ω multiscan mode, of which 3003 were
unique with Rint = 0.0228 and 2354 were observed with I >
2σ(I). The structure was solved by direct methods and refined
on F2 by full-matrix least-squares procedures using the
SHELX-97 program package10.All non-hydrogen atoms were
refined anisotropically. The hydrogen atoms attached to carbon
atoms were fixed at their ideal positions. The final R = 0.0595,
Index ranges (H, k, l)
–38 ≤ h ≤ 33, –38 ≤ k ≤ 38, –7 ≤ l ≤ 7
1.36–27.34
θ range for data collection
Reflections collected/unique
Completeness to θ
21212/3003(0.0228)
98.9 %
Goodness-of-fit on F2
Final R indices [I > 2σ(I)]
R indices (all data)
1.082
0.0595, 0.1645
0.0743, 0.1838
0.349/–0.287
Max. peak/hole (e Å–3)
TABLE-3
HYDROGEN BOND PARAMETERS
(Å, °) FOR THE TITLE COMPOUND
D–H···A
O(3)–H(3)···O(3)#1
Symmetry codes: #1 y + 3/4, –x + 5/4, –z + 5/4
d(D–H) d(H···A) d(D···A) <(DHA)
wR = 0.1645 (w = 1/[σ (Fo2) + (0.0979P)2 + 3.0971P], where
2
0.82 1.93 2.739(2) 171.6
P = (Fo2 + 2Fc2)/3), S = 1.082, (∆/σ)max = 0.001, (∆ρ)max
=
0.349 and (∆ρ)min = -0.287 e Å-3. The crystallographic data for
the title compound is summarized in Table-1. Selected bond
lengths and angles are listed in Table-2. Hydrogen bond
parameters are given in Table-3.
1021 cm-1, which are associated with O-C-O acetal bond
character. The compound was also characterized by NMR
spectroscopy, the H NMR spectra shows two sets of split
1
signals corresponding to the -CH2- protons of 1,3-dioxane ring.
These results indicate that the equatorial bond protons Heq
and straight bond protons Hax of -CH2- in 1,3-dioxane ring
produce coupling. The hydroxyl group displays a single signal
at δ = 1.654 ppm and the methyl group of the CH3-C fragment
has a single signal at δ = 1.510 ppm, these results demonstrates
the formation of the desired compound.
The molecular structure of compound was further con-
firmed by X-ray crystallography (Fig. 1). X-ray diffraction
analyses indicated that the title compound contains 1,3-dioxane
RESULTS AND DISCUSSION
The aldol reaction of 2,2-bis(hydroxymethyl)butanol
reacted with acetophenone in 1:1.1 molar ratio was then
conducted in DMF and cyclohexane with ionic liquid of 1-
acetyl-3-methylimidazole hydrogen sulfate as catalyst. Upon
recrystallization colourless crystals were isolated and
characterized to be the target products (Scheme-I).
The compound gave satifactory elemental analyses and
the IR spectra exhibits the strong absorption in the range 1088-
TABLE-2
SELECTED BOND LENGTHS (Å) AND BOND ANGLES (°)
Bonds
d
Bonds
d
Bonds
d
O(1)–C(7)
C(1)–C(2)
O(2)–C(10)
C(11)–C(10)
C(11)–C(9)
C(11)–C(12)
1.414(2)
1.379(3)
1.433(2)
1.524(2)
1.520(2)
1.523(2)
O(1)–C(9)
C(12)–C(13)
C(1)–C(6)
C(2)–C(3)
C(1)–C(7)
C(7)–C(8)
1.424(2)
1.501(3)
1.382(3)
1.396(3)
1.525(2)
1.512(2)
O(2)-C(7)
C(5)-C(4)
C(3)-C(4)
C(11)-C(14)
O(3)-C(14)
O(3)-C(14)
1.407(2)
1.361(4)
1.365(4)
1.532(2)
1.416(3)
1.416(3)
Angles
Angles
Angles
ω
ω
ω
C(7)-O(1)-C(9)
C(7)-O(2)-C(10)
C(9)-C(11)-C(12)
C(9)-C(11)-C(10)
C(12)-C(11)-C(10)
C(10)-C(11)-C(14)
O(2)-C(10)-C(11)
C(8)-C(7)-C(1)
114.16(12)
113.77(12)
110.12(15)
105.99(13)
109.12(15)
109.89(15)
111.50(14)
110.24(15)
119.9(2)
C(4)-C(5)-C(6)
C(2)-C(1)-C(6)
O(2)-C(7)-C(8)
C(2)-C(1)-C(7)
C(9)-C(11)-C(14)
O(1)-C(7)-C(8)
O(1)-C(7)-C(1)
O(3)-C(14)-C(11)
C(5)-C(6)-C(1)
120.6(3)
C(13)-C(12)-C(11)
C(4)-C(3)-C(2)
C(6)-C(1)-C(7)
O(2)-C(7)-O(1)
C(12)-C(11)-C(14)
O(2)-C(7)-C(1)
C(5)-C(4)-C(3)
O(1)-C(9)-C(11)
—
115.6(2)
120.6(3)
120.49(17)
111.05(13)
111.55(15)
111.68(13)
119.5(2)
111.97(14)
—
118.55(18)
106.72(15)
120.76(17)
110.02(15)
105.32(15)
111.54(14)
112.84(17)
120.8(2)
C(1)-C(2)-C(3)

Vol. 27, No. 6 (2015)
Synthesis and Crystal Structure of (5-Ethyl-2-methyl-2-phenyl-1,3-dioxan-5-yl)methanol 2101
rings and the phenyl substituent occupies an equatorial site.
The 1,3-dioxane ring displays chair conformation with torsion
angles for C7-O2-C10-C11 and C7-O1-C9-C11 being
57.07(18) and -55.99(19), respectively. In this crystal, adjacent
four molecules are connected by O-H···O (O3-H···O3#1 2.739(2)
Å, #1 y + 3/4, -x + 5/4, -z + 5/4) hydrogen bonding interactions
between the oxygen atoms into a tetramer (Fig. 2). The similar
Conclusion
In conclusion, the title compound (5-ethyl-2-methyl-2-
phenyl-1,3-dioxan-5-yl)methanol was synthesized by the
reaction of 2,2-bis(hydroxymethyl)butanol with acetophenone,
DMF and cyclohexane as solvent, ionic liquid of 1-acetyl-3-
methylimidazole hydrogen sulfate as catalyst, heating reflux
4 h. The yield was 53 % (1.3 g). The product was characterized
by 1H NMR, IR and single crystal X-ray diffraction, which was
confirmed to be in good agreement with the title compound.
crystal structures have been described in previous report1,11-13
.
ACKNOWLEDGEMENTS
This work was financially supported by the Construct
Program of the Key Discipline in Hunan Province (2011-76),
the Science and Technology Planning Project of Hunan
Province (2013FJ3004), the Scientific Research Fund of Hunan
Provincial Education Department (13A030, 14A058, 13C350),
the Key Laboratory of Functional Organometallic Materials
of Hunan Province College (13K09, 13K10), the Science and
Technology Innovative Research Team in Higher Educational
Institutions of Hunan Province (2012-318).
Fig. 1. Molecular structure of the title compound with atom numbering
scheme. Displacement ellipsoids are drawn at 30 % probability level
for non-H atoms
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Fig. 2. Four monomers are connected by hydrogen bonding interactions
into a tetramer. H atoms non-participating in hydrogen-bonding
were omitted for clarity