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A 1:1 adduct of methyl α-D -glucopyranoside and potassium hydrogen carbonate
122
CARBOHYDRATERESEARCH
NOte
A I:1 adduct hydrogen
of methyl carbonate*
a-D-glucopyranoside
and potassium
During an investigation of a reaction of methyl a-D-glucopytanoside (1) carried out in potassium hydroxide solution, a substance was isolated which apparently has not been reported previously’. It could be isolated when the basic solution was treated with carbon dioxide. The colorless crystalline solid (2) was recrystallized from 95% ethanol to m-p. 192-194” (with decomposition). Titrimetric analysis of the compound indicated an equivalent weight of 294.3, corresponding to the formula C,H,,OB - KHC03, a 1:l adduct of methyl a-D-glucopyranoside and potassium hydrogen carbonate. The elemental analysis was also consistent with this formula. A comparison of the i.r. spectra of 2 and 1 showed many similarities, but they were clearly not identical. Acetylation of 2 produced methyl 2,3,4,6-tetra-O-acetyl-a-D-glucopyranoside, identical with an authentic sample. A 2: 1 adduct of amylose and potassium hydrogen carbonate has been reported by Senti and Witnauer2. N.m.r. spectra of the adduct (2) and 1 were obtained in formamide and in methyl sulfoxide-d, (see Table I). In formamide solution, the hydroxyl-proton signals of 1 are centered at z 4.82, whereas those of the exchangeable hydrogens of 2 (four hydroxyl protons and the hydrogen carbonate proton) are masked by the solvent. A comparison of the spectra of 1 and 2 in methyl sulfoxide-d, showed that the hydroxyl-proton signals of 2 are shifted upfield3s4 by 0.5 p.p.m. Integration of the spectrum of 2 in methyl sulfoxide-d, before and after the addition of D,O showed that another exchangeable proton resonates in the z 6.38-6.98 region. It is presumed that this resonance is that of the hydrogen carbonate proton, because it has approximately the same chemical shift as the hydrogen carbonate proton in methyl sulfoxide-d6 solution. The adduct (2) can be recovered unchanged from formamide and from methyl sulfoxide-d, by addition of a less polar solvent. Synthesis of 2 was accomplished either by treating a potassium hydroxide solution containing 1 with carbon dioxide, or by bringing together equimolar amounts of 1 and potassium hydrogen carbonate in water.
Melting points are uncorrected. 1-r. spectra were recorded on a Perkin-Elmer Infracord spectrometer, MoGel 137. N.m.r. spectra were measured on a Varian *The University of Arizona, Agricultural Experiment Station, Paper No. 1360. Cmbdzyd. Res., 9 (1969) 122-124
NOTB
123
TABLE N-M-R.
I SPEClRAL
POTASSIUM
DATA
HYDROGEN
Compound
2-OH, 4-OH,
lb
4.82
FOR
METHYL
C(-D-GLUCOPYRANOSIDE
CARBONATE
ADDISC+
3-OH, 6-OH
H-i
20
Hycirogen carbonate proton
AND
THE
METHYL.
a-D-GLUCOPYRANOSIDE-
Ring protons
OMe
5.51d (2.6)
6.37-7.02
6.84
5.574
6.44-7. I 6
7.00
6.15-6.90
6.71
6.38-6.98
6.76
(3.1) KHC03b
1=
6.03 5.15-5.61
5.43d
(3.4) 2c
5.78-6.18
5.48
KHco3=
-6.9 6.71
“Chemicalshiftsare givenon the t scale, relative to Me&i @fezSO-&); d, doublet; J values(Hz) are given in parentheses. bIn HCONHz.
CIn MezSO-da.
Associates HA-100 spectrometer (100 MHz), and tetramethylsilane (z = 10.00) was used as the internal standard. Methyl sulfoxide-d, was obtained from Merck, Sharp and Dohme, Ltd., Canada, and was used without purification. All peaks assigned to hydroxyl groups were confirmed by exchange with deuterium oxide. The elemental analysis was performed by Schwarzkopf Microanalytical Laboratory, Woodside,
New York. Formation of methyl a-wghrcopyranoside-potassium hydrogen carbonate adduct (2) by carbonation. - A mixture of 5.0 g (90 mmoles) of potassium hydroxide,
50 g (250 mmoles) of methyl a-D-glucopyranoside, and 50 ml of water was warmed to give a clear solution. The solution was cooled to room temperature, and carbon dioxide gas was bubbled through it until no further change in pH occurred. The solution was evaporated to dryness on a rotary evaporator, and the residue was extracted with five IOO-ml portions of hot 95% ethanol_ The extracts were combined, and kept overnight at room temperature, and the crystalline material that separated was collected by filtration. This crude product, m.p. 191-194” (dec.), was recrystallized from 95% ethanol to give 22.5 g (85%) of colorless, cryst.alline product; m-p. 192194” dec., vy; 3600-3200 YS, 2900 m, 1440 m, 1920 m, 1360 m, 1330 m, 1280 sh, 1190 w, 1145 m, 1110 m, 1075 sh, 1050 vs, 1025 vs, 1010 sh, 990 sh, 918 sh, 900 w, Methyl a-D-glucopyranoside gave v=g 3600-3200 vs, 835 w, and 755 w cm-‘. 2900 m, 1450 w, 1420 w, 1390 sh, 1360 w, 1330 w, 1280 sh, 1260 w, 1220 w, 1190 m, 1140 ms, 1110 ms, 1100 ms, 1070 sh, 1060 sh, 1055 vs, 1045 vs, 990 ms, 900 w, 845 w, and 745 w cm-‘. (Both spectra were calibrated by means of the polystyrene band at 1601 cm-‘.) Carbohyd
Res., 9 (1969) 122-124
NOTE
124
.4nul. Calc. for /r LsH15K09: C, 32.65; H, 5.15, ash (K), 13.29. Found: C, 32.49; H, 5.10, rsh (K), 13.06. Formation of methyl a-D-glucopyranoside-potassium hydrogen . carbonate adduct (2) from the component compounds. - To a sohrtion of 20 g (200 mmoIes) of potassium hydrogen carbonate in 50 ml of water was added 39 g (200 mmoles) of methyl a-D-ghrcopyranoside. The mixture was warmed, and the resulting solution was evaporated to dryness on a rotary evaporator. The residue was extracted with nine lOOmI portions of 95% ethanol, and the extracts were combined, and kept overnight at room temperature. The crude product that separated was recrystallized from 95%
ethanol to give 49 g (83%)
of colorless crystals, m-p. 192-194O (dec.).
Formation of methyl 2,3,4,6-tetra-0-acetyl-a-D-glucopyranoside by acetylation of the adduct (2). - Acetylation of 2.9 g (10 mmoles) of 2 was accomplished according to a published procedure 5. The product, yield 2.35 g (65%), was identical in all respects with an authentic sample of the tetraacetate. ACKNOWLEDGMENTS
This work was done under contract with the U.S. Departmeut of Agriculture, and authorized by the Research and Marketing Act. The contract was supervised by the Northern Utilization Research and Development Division, Agricultural Research Service.
Department of AgricuItural Biochemistry, University of Arizona, Tucson, Arizona 85721 (U. S. A.)
J. W. BERRY B. I. MAYALL J. T. MARVEL A. J. DEUTSCHIUN,JR.
REFERENCES 1 J. A. RENDLE~~AN,Jn., Aduun. Curbohyd. Chenr., 21 (1966) 216. 2 F. R. SENI-I AND L. P. WITNAUER, J. Polymer Sri., 9 (1952) 115. 3 B. CASU, M. REGGUNNI, G. GALLO, AND A. VIGEVANI, TetrahedronLet& (1965) 2253. 4 J. T. MARVEL, S. K. SEN, J. W. BERRY, AND A. J. DEUTSCHMAN.JR., Carbohyd. Res-, 8 (1968) 5 G. N. BOLLENBACK, Methods Carbohyd. Chem., 2 (1963) 327. (Received June 7th. 1968)
Curbohyd. Res., 9 (1969) 122-124
148.
CARBOHYDRATERESEARCH
NOte
A I:1 adduct hydrogen
of methyl carbonate*
a-D-glucopyranoside
and potassium
During an investigation of a reaction of methyl a-D-glucopytanoside (1) carried out in potassium hydroxide solution, a substance was isolated which apparently has not been reported previously’. It could be isolated when the basic solution was treated with carbon dioxide. The colorless crystalline solid (2) was recrystallized from 95% ethanol to m-p. 192-194” (with decomposition). Titrimetric analysis of the compound indicated an equivalent weight of 294.3, corresponding to the formula C,H,,OB - KHC03, a 1:l adduct of methyl a-D-glucopyranoside and potassium hydrogen carbonate. The elemental analysis was also consistent with this formula. A comparison of the i.r. spectra of 2 and 1 showed many similarities, but they were clearly not identical. Acetylation of 2 produced methyl 2,3,4,6-tetra-O-acetyl-a-D-glucopyranoside, identical with an authentic sample. A 2: 1 adduct of amylose and potassium hydrogen carbonate has been reported by Senti and Witnauer2. N.m.r. spectra of the adduct (2) and 1 were obtained in formamide and in methyl sulfoxide-d, (see Table I). In formamide solution, the hydroxyl-proton signals of 1 are centered at z 4.82, whereas those of the exchangeable hydrogens of 2 (four hydroxyl protons and the hydrogen carbonate proton) are masked by the solvent. A comparison of the spectra of 1 and 2 in methyl sulfoxide-d, showed that the hydroxyl-proton signals of 2 are shifted upfield3s4 by 0.5 p.p.m. Integration of the spectrum of 2 in methyl sulfoxide-d, before and after the addition of D,O showed that another exchangeable proton resonates in the z 6.38-6.98 region. It is presumed that this resonance is that of the hydrogen carbonate proton, because it has approximately the same chemical shift as the hydrogen carbonate proton in methyl sulfoxide-d6 solution. The adduct (2) can be recovered unchanged from formamide and from methyl sulfoxide-d, by addition of a less polar solvent. Synthesis of 2 was accomplished either by treating a potassium hydroxide solution containing 1 with carbon dioxide, or by bringing together equimolar amounts of 1 and potassium hydrogen carbonate in water.
Melting points are uncorrected. 1-r. spectra were recorded on a Perkin-Elmer Infracord spectrometer, MoGel 137. N.m.r. spectra were measured on a Varian *The University of Arizona, Agricultural Experiment Station, Paper No. 1360. Cmbdzyd. Res., 9 (1969) 122-124
NOTB
123
TABLE N-M-R.
I SPEClRAL
POTASSIUM
DATA
HYDROGEN
Compound
2-OH, 4-OH,
lb
4.82
FOR
METHYL
C(-D-GLUCOPYRANOSIDE
CARBONATE
ADDISC+
3-OH, 6-OH
H-i
20
Hycirogen carbonate proton
AND
THE
METHYL.
a-D-GLUCOPYRANOSIDE-
Ring protons
OMe
5.51d (2.6)
6.37-7.02
6.84
5.574
6.44-7. I 6
7.00
6.15-6.90
6.71
6.38-6.98
6.76
(3.1) KHC03b
1=
6.03 5.15-5.61
5.43d
(3.4) 2c
5.78-6.18
5.48
KHco3=
-6.9 6.71
“Chemicalshiftsare givenon the t scale, relative to Me&i @fezSO-&); d, doublet; J values(Hz) are given in parentheses. bIn HCONHz.
CIn MezSO-da.
Associates HA-100 spectrometer (100 MHz), and tetramethylsilane (z = 10.00) was used as the internal standard. Methyl sulfoxide-d, was obtained from Merck, Sharp and Dohme, Ltd., Canada, and was used without purification. All peaks assigned to hydroxyl groups were confirmed by exchange with deuterium oxide. The elemental analysis was performed by Schwarzkopf Microanalytical Laboratory, Woodside,
New York. Formation of methyl a-wghrcopyranoside-potassium hydrogen carbonate adduct (2) by carbonation. - A mixture of 5.0 g (90 mmoles) of potassium hydroxide,
50 g (250 mmoles) of methyl a-D-glucopyranoside, and 50 ml of water was warmed to give a clear solution. The solution was cooled to room temperature, and carbon dioxide gas was bubbled through it until no further change in pH occurred. The solution was evaporated to dryness on a rotary evaporator, and the residue was extracted with five IOO-ml portions of hot 95% ethanol_ The extracts were combined, and kept overnight at room temperature, and the crystalline material that separated was collected by filtration. This crude product, m.p. 191-194” (dec.), was recrystallized from 95% ethanol to give 22.5 g (85%) of colorless, cryst.alline product; m-p. 192194” dec., vy; 3600-3200 YS, 2900 m, 1440 m, 1920 m, 1360 m, 1330 m, 1280 sh, 1190 w, 1145 m, 1110 m, 1075 sh, 1050 vs, 1025 vs, 1010 sh, 990 sh, 918 sh, 900 w, Methyl a-D-glucopyranoside gave v=g 3600-3200 vs, 835 w, and 755 w cm-‘. 2900 m, 1450 w, 1420 w, 1390 sh, 1360 w, 1330 w, 1280 sh, 1260 w, 1220 w, 1190 m, 1140 ms, 1110 ms, 1100 ms, 1070 sh, 1060 sh, 1055 vs, 1045 vs, 990 ms, 900 w, 845 w, and 745 w cm-‘. (Both spectra were calibrated by means of the polystyrene band at 1601 cm-‘.) Carbohyd
Res., 9 (1969) 122-124
NOTE
124
.4nul. Calc. for /r LsH15K09: C, 32.65; H, 5.15, ash (K), 13.29. Found: C, 32.49; H, 5.10, rsh (K), 13.06. Formation of methyl a-D-glucopyranoside-potassium hydrogen . carbonate adduct (2) from the component compounds. - To a sohrtion of 20 g (200 mmoIes) of potassium hydrogen carbonate in 50 ml of water was added 39 g (200 mmoles) of methyl a-D-ghrcopyranoside. The mixture was warmed, and the resulting solution was evaporated to dryness on a rotary evaporator. The residue was extracted with nine lOOmI portions of 95% ethanol, and the extracts were combined, and kept overnight at room temperature. The crude product that separated was recrystallized from 95%
ethanol to give 49 g (83%)
of colorless crystals, m-p. 192-194O (dec.).
Formation of methyl 2,3,4,6-tetra-0-acetyl-a-D-glucopyranoside by acetylation of the adduct (2). - Acetylation of 2.9 g (10 mmoles) of 2 was accomplished according to a published procedure 5. The product, yield 2.35 g (65%), was identical in all respects with an authentic sample of the tetraacetate. ACKNOWLEDGMENTS
This work was done under contract with the U.S. Departmeut of Agriculture, and authorized by the Research and Marketing Act. The contract was supervised by the Northern Utilization Research and Development Division, Agricultural Research Service.
Department of AgricuItural Biochemistry, University of Arizona, Tucson, Arizona 85721 (U. S. A.)
J. W. BERRY B. I. MAYALL J. T. MARVEL A. J. DEUTSCHIUN,JR.
REFERENCES 1 J. A. RENDLE~~AN,Jn., Aduun. Curbohyd. Chenr., 21 (1966) 216. 2 F. R. SENI-I AND L. P. WITNAUER, J. Polymer Sri., 9 (1952) 115. 3 B. CASU, M. REGGUNNI, G. GALLO, AND A. VIGEVANI, TetrahedronLet& (1965) 2253. 4 J. T. MARVEL, S. K. SEN, J. W. BERRY, AND A. J. DEUTSCHMAN.JR., Carbohyd. Res-, 8 (1968) 5 G. N. BOLLENBACK, Methods Carbohyd. Chem., 2 (1963) 327. (Received June 7th. 1968)
Curbohyd. Res., 9 (1969) 122-124
148.