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Annealing of α-lactose monohydrate at 408 K yielded a mixture of this compound with hygroscopic anhydrous α-lactose. A powder X-ray diffraction pattern of this mixture was recorded at room temperature. The starting structural model of hygroscopic α-lactose was found by a Monte Carlo simulated-annealing method. The final structure was obtained through Rietveld refinements, with soft restraints on inter­atomic bond lengths and bond angles, and crystalline energy minimization to locate the H atoms of the hydroxy groups. The crystalline cohesion is achieved by networks of O—H...O hydrogen bonds that differ from those of the monohydrate phase. The width of the Bragg peaks is interpreted by a phenomenological microstructural approach in terms of isotropic size effects and anisotropic strain effects.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108768104014375/lc5007sup1.cif
Contains datablocks global, hygroscopic_alpha_lactose

txt

Text file https://doi.org/10.1107/S0108768104014375/lc5007sup2.txt
Supplementary material

pdf

Portable Document Format (PDF) file https://doi.org/10.1107/S0108768104014375/lc5007sup3.pdf
Supplementary material

CCDC reference: 248466

Experimental top

Commercially available alpha-L—H2O was used for this experiment (SIGMA Company). In order to obtain the alpha-LH phase, the following procedure was used: powder of alpha-L—H2O contained in a crystallizer was annealed in an oven during 30 minutes at a given temperature T. To avoid possible rehydration, the powder was introduced in a Lindemann glass capillary then sealed rapidly for X-ray powder diffraction experiment. Attempts were done at different temperatures. For temperatures lower than 120 °C, only peaks of the alpha-L—H2O phase are present in the patterns. From 125 to 135 °C, in addition to the peaks of the alpha-L—H2O phase, new peaks appear which correspond to the ?LH phase according to Buma & Wiegers (1967). At 140 °C, the alpha-L—H2O disappears, and with the peaks of the ?LH form, there are new peaks of diffraction characterizing the alpha-LS phase (Van Kreveld, 1969). The part of the powder not used for the X-ray experiment was kept at the air contact. After a week, this powder was analysed by X-ray diffraction and only the alpha-L—H2O phase was found. This experiment confirms that the supplementary peaks correspond to the unstable hygroscopic alpha-LH phase.

Computing details top

Data collection: PEAKOC; program(s) used to solve structure: FOX; program(s) used to refine structure: FULLPROF; molecular graphics: ORTEP-3; software used to prepare material for publication: SHELX97 and PARST.

Figures top
[Figure 1] Fig. 1. : Final Rietveld plot of the hygroscopic phase of alpha-lactose. Observed data points are indicated by dots, the best-fit profile (upper trace) and the difference pattern (lower trace) are solid lines. The vertical bars correspond to the position of Bragg peaks: upper bars for alpha-LH, lower bars for alpha-L—H2O.
[Figure 2] Fig. 2. : Atomic numbering and molecular structure of the hygroscopic phase of alpha-lactose. The dashed bond represents the internal H bond of the molecule of lactose.
[Figure 3] Fig. 3. : Projection of the unit cell of the hygroscopic alpha-lactose along c*. Blue lines correspond to H bonds.
[Figure 4] Fig. 4. : Projection of the unit cell of the hygroscopic alpha-lactose along the twofold screw axis. Only molecules around y = 0 are drawn. Blue lines correspond to H bonds.
[Figure 5] Fig. 5. : Strain values on the alpha-LH phase for different directions of the lattice (black curves): a) in the monoclinic plane, b), c) and d) correspond to planes form by the twofold axis and a direction of an extreme value of the strain in the monoclinic plane (phi is the angle between the lattice parameter a and this direction): b) phi = 21.5 degrees, c) phi = 81 degrees and d) phi =142 degrees. The red curves correspond to the strain values for the commercial alphaL-H2O.
4-O-beta-D-galactopyranosyl-D-glucopyranose top
Crystal data top
C12H22O11Z = 2
Mr = 342.30F(000) = 364
Monoclinic, P21Dx = 1.557 Mg m3
Hall symbol: P 2ybCu Kα radiation, λ = 1.540560 Å
a = 7.7795 (2) ŵ = 1.22 mm1
b = 19.6931 (6) ÅT = 293 K
c = 4.90643 (11) Åwhite
β = 103.6909 (15)°cylinder, diameter 0.7 mm, ? × ? × ? mm
V = 730.32 (3) Å3Specimen preparation: Prepared at 293 K
Data collection top
Enraf Nonius FR 590
diffractometer
Data collection mode: transmission
Radiation source: sealed X-ray tubeScan method: Stationary detector
Quartz (curved monochromator)Absorption correction: for a cylinder mounted on the ϕ axis
?
Specimen mounting: Lindemann glass capillaryTmin = ?, Tmax = ?
Refinement top
Rp = 2.161Profile function: pseudo-Voigt
Rwp = 3.090136 parameters
Rexp = 2.21859 restraints
RBragg = 1.632
χ2 = NOT FOUNDBackground function: linear interpolation between 32 points
3946 data pointsPreferred orientation correction: March-Dollase function, axis [0, 0, 1], G1 = 1.089 (4), G2 = 0
Excluded region(s): 0.291 to 8.50 : no Bragg peaks 80.00 to 114.696 : peak intensities too low
Crystal data top
C12H22O11V = 730.32 (3) Å3
Mr = 342.30Z = 2
Monoclinic, P21Cu Kα radiation, λ = 1.540560 Å
a = 7.7795 (2) ŵ = 1.22 mm1
b = 19.6931 (6) ÅT = 293 K
c = 4.90643 (11) Åcylinder, diameter 0.7 mm, ? × ? × ? mm
β = 103.6909 (15)°
Data collection top
Enraf Nonius FR 590
diffractometer
Scan method: Stationary detector
Specimen mounting: Lindemann glass capillaryAbsorption correction: for a cylinder mounted on the ϕ axis
?
Data collection mode: transmissionTmin = ?, Tmax = ?
Refinement top
Rp = 2.161χ2 = NOT FOUND
Rwp = 3.0903946 data points
Rexp = 2.218136 parameters
RBragg = 1.63259 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.3236 (10)0.0424 (5)0.763 (3)0.036 (2)
C20.4658 (11)0.0969 (5)0.832 (2)0.036 (2)
C30.3978 (11)0.1444 (5)1.025 (3)0.036 (2)
C40.2173 (12)0.1728 (5)0.8801 (8)0.036 (2)
C50.0932 (12)0.1124 (5)0.788 (2)0.036 (2)
C60.0800 (16)0.1293 (7)0.586 (4)0.036 (2)
O10.4001 (16)0.0000 (1)0.587 (3)0.036 (2)
O20.6248 (14)0.0728 (8)1.001 (3)0.036 (2)
O30.5085 (17)0.1997 (7)1.140 (3)0.036 (2)
O40.2244 (17)0.2102 (8)0.637 (2)0.036 (2)
O50.1545 (13)0.0670 (6)0.608 (2)0.036 (2)
O60.1938 (16)0.0721 (6)0.559 (3)0.036 (2)
H10.314100.017700.937900.036 (2)
H20.482900.120900.659100.036 (2)
H30.381500.116701.187000.036 (2)
H40.171000.202001.015200.036 (2)
H50.070800.087800.955100.036 (2)
H6a0.057900.141000.396800.036 (2)
H6b0.135700.169600.650200.036 (2)
HO20.707160.065470.873320.036 (2)
HO30.447060.224351.264350.036 (2)
HO40.173830.255290.669230.036 (2)
HO60.278390.074160.370470.036 (2)
C1'0.3291 (11)0.2011 (8)0.3302 (17)0.036 (2)
C2'0.1633 (10)0.1684 (4)0.387 (3)0.036 (2)
C3'0.1863 (10)0.0912 (4)0.396 (3)0.036 (2)
C4'0.3554 (11)0.0699 (4)0.612 (3)0.036 (2)
C5'0.5109 (10)0.1105 (5)0.552 (3)0.036 (2)
C6'0.6885 (12)0.0982 (9)0.756 (4)0.036 (2)
O1'0.3408 (16)0.1899 (8)0.050 (2)0.036 (2)
O2'0.0033 (11)0.1877 (7)0.215 (3)0.036 (2)
O3'0.0365 (15)0.0597 (7)0.461 (3)0.036 (2)
O5'0.4887 (13)0.1833 (4)0.532 (2)0.036 (2)
O6'0.8254 (14)0.1380 (6)0.686 (3)0.036 (2)
H1'0.314900.251700.350800.036 (2)
H2'0.160100.181700.581600.036 (2)
H3'0.194300.075200.203500.036 (2)
H4'0.342100.079600.803100.036 (2)
H5'0.524500.095700.362300.036 (2)
H6a'0.682000.107000.949200.036 (2)
H6b'0.722600.048500.744700.036 (2)
HO1'0.427740.225350.025730.036 (2)
HO2'0.001500.167090.018790.036 (2)
HO3'0.040680.009810.424410.036 (2)
HO6'0.864420.114060.527330.036 (2)
Geometric parameters (Å, º) top
C1—O11.427 (16)O6—HO61.002
C1—O51.439 (13)C1'—O1'1.418 (14)
C1—C21.522 (12)C1'—O5'1.435 (12)
C1—H11.003C1'—C2'1.527 (14)
C2—O21.400 (14)C1'—H1'1.010
C2—C31.513 (14)C2'—O2'1.421 (13)
C2—H21.006C2'—C3'1.529 (12)
C3—O31.419 (15)C2'—H2'0.994
C3—C41.522 (12)C3'—O3'1.421 (17)
C3—H30.997C3'—C4'1.539 (13)
C4—O41.412 (15)C3'—H3'1.014
C4—C51.531 (11)C4'—C5'1.537 (14)
C4—H41.006C4'—H4'0.985
C5—O51.417 (13)C5'—O5'1.445 (12)
C5—C61.509 (15)C5'—C6'1.522 (14)
C5—H51.002C5'—H5'1.002
C6—O61.420 (17)C6'—O6'1.427 (19)
C6—H6A1.009C6'—H6A'0.978
C6—H6B0.991C6'—H6B'1.019
O1—C4'1.432 (9)O1'—HO1'0.999
O2—HO21.009O2'—HO2'1.054
O3—HO30.989O3'—HO3'1.000
O4—HO40.998O6'—HO6'1.016
O1—C1—O5109.7 (7)O1'—C1'—O5'112.8 (8)
O1—C1—C299.3 (7)O1'—C1'—C2'111.3 (9)
O5—C1—C2113.8 (8)O5'—C1'—C2'113.7 (8)
O1—C1—H1111.0O1'—C1'—H1'106.5
O5—C1—H1111.9O5'—C1'—H1'105.6
C2—C1—H1110.5C2'—C1'—H1'106.3
O2—C2—C3103.2 (8)O2'—C2'—C1'118.0 (8)
O2—C2—C1112.7 (9)O2'—C2'—C3'111.5 (9)
C3—C2—C1103.4 (8)C1'—C2'—C3'109.1 (8)
O2—C2—H2112.6O2'—C2'—H2'105.8
C3—C2—H2111.9C1'—C2'—H2'106.1
C1—C2—H2112.3C3'—C2'—H2'105.3
O3—C3—C2116.9 (7)O3'—C3'—C2'110.1 (8)
O3—C3—C4108.0 (9)O3'—C3'—C4'109.9 (8)
C2—C3—C4110.8 (7)C2'—C3'—C4'111.5 (7)
O3—C3—H3106.4O3'—C3'—H3'107.9
C2—C3—H3106.9C2'—C3'—H3'108.3
C4—C3—H3107.2C4'—C3'—H3'109.0
O4—C4—C3111.7 (6)O1—C4'—C5'105.4 (6)
O4—C4—C5107.7 (8)O1—C4'—C3'112.9 (7)
C3—C4—C5107.4 (5)C5'—C4'—C3'108.0 (7)
O4—C4—H4110.5O1—C4'—H4'110.5
C3—C4—H4109.7C5'—C4'—H4'110.3
C5—C4—H4109.8C3'—C4'—H4'109.7
O5—C5—C696.2 (7)O5'—C5'—C6'106.1 (10)
O5—C5—C4113.1 (5)O5'—C5'—C4'116.3 (8)
C6—C5—C4115.2 (6)C6'—C5'—C4'115.1 (8)
O5—C5—H5110.7O5'—C5'—H5'105.3
C6—C5—H5110.1C6'—C5'—H5'106.5
C4—C5—H5110.8C4'—C5'—H5'106.8
O6—C6—C5109.0 (10)O6'—C6'—C5'111.6 (9)
O6—C6—H6A109.6O6'—C6'—H6A'110.4
C5—C6—H6A109.6C5'—C6'—H6A'111.2
O6—C6—H6B110.7O6'—C6'—H6B'107.3
C5—C6—H6B110.8C5'—C6'—H6B'109.0
H6A—C6—H6B107.0H6A'—C6'—H6B'107.2
C1—O1—C4'111.5 (5)C1'—O1'—HO1'101.9
C2—O2—HO2106.3C2'—O2'—HO2'102.5
C3—O3—HO3106.6C3'—O3'—HO3'109.0
C4—O4—HO4103.7C1'—O5'—C5'111.0 (9)
C5—O5—C1106.5 (8)C6'—O6'—HO6'107.7
C6—O6—HO6108.1
O1—C1—C2—O268.2 (11)O1'—C1'—C2'—O2'57.1 (14)
O5—C1—C2—O2175.2 (10)O5'—C1'—C2'—O2'174.3 (10)
O1—C1—C2—C3178.9 (8)O1'—C1'—C2'—C3'71.5 (12)
O5—C1—C2—C364.5 (11)O5'—C1'—C2'—C3'57.1 (12)
O2—C2—C3—O359.0 (9)O2'—C2'—C3'—O3'50.3 (13)
C1—C2—C3—O3176.6 (9)C1'—C2'—C3'—O3'177.6 (10)
O2—C2—C3—C4176.6 (8)O2'—C2'—C3'—C4'172.6 (9)
C1—C2—C3—C459.0 (12)C1'—C2'—C3'—C4'55.3 (11)
O3—C3—C4—O468.7 (11)C1—O1—C4'—C5'150.9 (9)
C2—C3—C4—O460.6 (10)C1—O1—C4'—C3'91.5 (11)
O3—C3—C4—C5173.4 (8)O3'—C3'—C4'—O169.4 (12)
C2—C3—C4—C557.3 (8)C2'—C3'—C4'—O1168.2 (9)
O4—C4—C5—O562.7 (10)O3'—C3'—C4'—C5'174.5 (10)
C3—C4—C5—O557.8 (9)C2'—C3'—C4'—C5'52.1 (11)
O4—C4—C5—C646.6 (11)O1—C4'—C5'—O5'173.1 (9)
C3—C4—C5—C6167.1 (8)C3'—C4'—C5'—O5'52.2 (12)
O5—C5—C6—O671.5 (12)O1—C4'—C5'—C6'61.9 (12)
C4—C5—C6—O6169.4 (9)C3'—C4'—C5'—C6'177.2 (10)
O5—C1—O1—C4'92.3 (11)O5'—C5'—C6'—O6'49.6 (14)
C2—C1—O1—C4'148.1 (9)C4'—C5'—C6'—O6'179.6 (11)
C6—C5—O5—C1179.0 (10)O1'—C1'—O5'—C5'72.2 (12)
C4—C5—O5—C160.2 (10)C2'—C1'—O5'—C5'55.6 (12)
O1—C1—O5—C5175.7 (8)C6'—C5'—O5'—C1'176.5 (10)
C2—C1—O5—C565.5 (11)C4'—C5'—O5'—C1'54.1 (12)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—HO2···O6i1.009 (19)1.88 (2)2.85 (2)160.8 (13)
O3—HO3···O5ii0.99 (2)2.078 (16)2.809 (16)129.2 (13)
O4—HO4···O2iii1.00 (2)1.924 (19)2.849 (19)152.8 (15)
O6—HO6···O2iv1.002 (17)1.789 (18)2.767 (18)164.2 (15)
O1—HO1···O3v1.00 (2)1.81 (2)2.74 (2)152.7 (15)
O2—HO2···O6iv1.054 (19)1.953 (16)2.800 (18)135.0 (13)
O3—HO3···O51.00 (2)1.873 (17)2.697 (18)137.6 (15)
O6—HO6···O3i1.02 (2)1.805 (17)2.674 (19)141.5 (15)
Symmetry codes: (i) x+1, y, z; (ii) x+1, y+1/2, z+2; (iii) x, y+1/2, z+1; (iv) x1, y, z1; (v) x+1, y1/2, z+1.

Experimental details

Crystal data
Chemical formulaC12H22O11
Mr342.30
Crystal system, space groupMonoclinic, P21
Temperature (K)293
a, b, c (Å)7.7795 (2), 19.6931 (6), 4.90643 (11)
β (°) 103.6909 (15)
V3)730.32 (3)
Z2
Radiation typeCu Kα, λ = 1.540560 Å
µ (mm1)1.22
Specimen shape, size (mm)Cylinder, diameter 0.7 mm, ? × ? × ?
Data collection
DiffractometerEnraf Nonius FR 590
diffractometer
Specimen mountingLindemann glass capillary
Data collection modeTransmission
Scan methodStationary detector
2θ values (°)2θfixed = ?
Refinement
R factors and goodness of fitRp = 2.161, Rwp = 3.090, Rexp = 2.218, RBragg = 1.632, χ2 = NOT FOUND
No. of data points3946
No. of parameters136
No. of restraints59

Computer programs: PEAKOC, FOX, FULLPROF, ORTEP-3, SHELX97 and PARST.

Selected geometric parameters (Å, º) top
C1—O11.427 (16)O1—C4'1.432 (9)
C1—O51.439 (13)C1'—O1'1.418 (14)
C1—C21.522 (12)C1'—O5'1.435 (12)
C2—O21.400 (14)C1'—C2'1.527 (14)
C2—C31.513 (14)C2'—O2'1.421 (13)
C3—O31.419 (15)C2'—C3'1.529 (12)
C3—C41.522 (12)C3'—O3'1.421 (17)
C4—O41.412 (15)C3'—C4'1.539 (13)
C4—C51.531 (11)C4'—C5'1.537 (14)
C5—O51.417 (13)C5'—O5'1.445 (12)
C5—C61.509 (15)C5'—C6'1.522 (14)
C6—O61.420 (17)C6'—O6'1.427 (19)
O1—C1—O5109.7 (7)O1'—C1'—O5'112.8 (8)
O1—C1—C299.3 (7)O1'—C1'—C2'111.3 (9)
O5—C1—C2113.8 (8)O5'—C1'—C2'113.7 (8)
O2—C2—C3103.2 (8)O2'—C2'—C1'118.0 (8)
O2—C2—C1112.7 (9)O2'—C2'—C3'111.5 (9)
C3—C2—C1103.4 (8)C1'—C2'—C3'109.1 (8)
O3—C3—C2116.9 (7)O3'—C3'—C2'110.1 (8)
O3—C3—C4108.0 (9)O3'—C3'—C4'109.9 (8)
C2—C3—C4110.8 (7)C2'—C3'—C4'111.5 (7)
O4—C4—C3111.7 (6)O1—C4'—C5'105.4 (6)
O4—C4—C5107.7 (8)O1—C4'—C3'112.9 (7)
C3—C4—C5107.4 (5)C5'—C4'—C3'108.0 (7)
O5—C5—C696.2 (7)O5'—C5'—C6'106.1 (10)
O5—C5—C4113.1 (5)O5'—C5'—C4'116.3 (8)
C6—C5—C4115.2 (6)C6'—C5'—C4'115.1 (8)
O6—C6—C5109.0 (10)O6'—C6'—C5'111.6 (9)
C1—O1—C4'111.5 (5)C1'—O5'—C5'111.0 (9)
C5—O5—C1106.5 (8)
O1—C1—C2—O268.2 (11)O1'—C1'—C2'—O2'57.1 (14)
O5—C1—C2—O2175.2 (10)O5'—C1'—C2'—O2'174.3 (10)
O1—C1—C2—C3178.9 (8)O1'—C1'—C2'—C3'71.5 (12)
O5—C1—C2—C364.5 (11)O5'—C1'—C2'—C3'57.1 (12)
O2—C2—C3—O359.0 (9)O2'—C2'—C3'—O3'50.3 (13)
C1—C2—C3—O3176.6 (9)C1'—C2'—C3'—O3'177.6 (10)
O2—C2—C3—C4176.6 (8)O2'—C2'—C3'—C4'172.6 (9)
C1—C2—C3—C459.0 (12)C1'—C2'—C3'—C4'55.3 (11)
O3—C3—C4—O468.7 (11)C1—O1—C4'—C5'150.9 (9)
C2—C3—C4—O460.6 (10)C1—O1—C4'—C3'91.5 (11)
O3—C3—C4—C5173.4 (8)O3'—C3'—C4'—O169.4 (12)
C2—C3—C4—C557.3 (8)C2'—C3'—C4'—O1168.2 (9)
O4—C4—C5—O562.7 (10)O3'—C3'—C4'—C5'174.5 (10)
C3—C4—C5—O557.8 (9)C2'—C3'—C4'—C5'52.1 (11)
O4—C4—C5—C646.6 (11)O1—C4'—C5'—O5'173.1 (9)
C3—C4—C5—C6167.1 (8)C3'—C4'—C5'—O5'52.2 (12)
O5—C5—C6—O671.5 (12)O1—C4'—C5'—C6'61.9 (12)
C4—C5—C6—O6169.4 (9)C3'—C4'—C5'—C6'177.2 (10)
O5—C1—O1—C4'92.3 (11)O5'—C5'—C6'—O6'49.6 (14)
C2—C1—O1—C4'148.1 (9)C4'—C5'—C6'—O6'179.6 (11)
C6—C5—O5—C1179.0 (10)O1'—C1'—O5'—C5'72.2 (12)
C4—C5—O5—C160.2 (10)C2'—C1'—O5'—C5'55.6 (12)
O1—C1—O5—C5175.7 (8)C6'—C5'—O5'—C1'176.5 (10)
C2—C1—O5—C565.5 (11)C4'—C5'—O5'—C1'54.1 (12)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—HO2···O6i1.009 (19)1.883 (21)2.854 (21)160.8 (13)
O3—HO3···O5'ii0.989 (20)2.078 (16)2.809 (16)129.2 (13)
O4—HO4···O2'iii0.998 (21)1.924 (19)2.849 (19)152.8 (15)
O6—HO6···O2iv1.002 (17)1.789 (18)2.767 (18)164.2 (15)
O1'—HO1'···O3v0.999 (20)1.810 (20)2.736 (20)152.7 (15)
O2'—HO2'···O6'iv1.054 (19)1.953 (16)2.800 (18)135.0 (13)
O3'—HO3'···O51.000 (21)1.873 (17)2.697 (18)137.6 (15)
O6'—HO6'···O3'i1.016 (21)1.805 (17)2.674 (19)141.5 (15)
Symmetry codes: (i) x+1, y, z; (ii) x+1, y+1/2, z+2; (iii) x, y+1/2, z+1; (iv) x1, y, z1; (v) x+1, y1/2, z+1.
 

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