Carbohydrate Research, 111 (1982) 1-7 Elsevier Scientilic Publishing Company, Amsterdam - Printed in The Netherlands
G.L.C.-M.S. OF THE OXIDATION PRODUCTS OF PENTITOLS AND HEXITOLS AS 0-BUTYLOXIME TRIFLUOROACETATES HORST SCHWEER Chemical Institute, Veterinary School, Bischofsholer Damm IS, 3000 Hannover (West Germany)
(Received September lOth, 1981; accepted for publication, June 9th, 1982)
ABSTRACT
Chemical ionisation (c.i.) mass spectra of trifluoroacetylated 0-butyloximes of 2- and 3-pentuloses, 2- and 3-hexuloses, and 2,5-hexodiuloses (products of the oxidation of the pentitols and hexitols with bromine) are reported. Small amounts of 2-pentosuloses and 2,3- and 2,4-pentodiuloses could be detected by using selected ion monitoring at m/z 579 (M + 1). The mass spectra comprise few signals, with those for (M + 1) or (M + 1 - 2 F&-COO) being the most intense. INTRODUCTION
The separation of pentosesi*2, hexoses3s4, 2- and 3-pentuloses, 2- and 3hexuloses, and 2,5-hexodiuloses’ as 0-butyl-, O-methyl-, and 0-(2-methyl-2-propyl)oxime derivatives by g.1.c. on OV-225 has been reported. We now present g.l.c.-m.s. data on trifluoroacetylated 2- and 3-pentulose, 2- and 3-hexulose, and 2,5-hexodiulose 0-butyloxime derivatives which may be useful in the analysis of biological material6 and of complex sugar mixtures arising in the formose reaction”‘. Trimethylsilylated and acetylated carbohydrate 0-alkyloximes are acyclic9,10, and 2 (syn) and E (anti) isomers are formed. Diuloses may give up to four isomers’1,‘2. EXPERIMENTAL Materials. - D-erythro-2-Pentosulose and D-threo-2-pentosulose were obtained13 by oxidation of D-ribose and D-xylose with Cu(I1) acetate, and allitol, D-altI%Ol, and D-iditol by conventional reduction of D-allose, D&lose, and D-idose, respectively, with borohydride. Other chemicals were commercial products. Oxidation of alditols and derivatisation of products. - Oxidation was effected with bromine in the presence of calcium carbonate, acids were removed with an ionexchange resin, and derivatisation was carried out as described previously’. G.l.c.-m.s. - An MAT 44s gas chromatograph-mass spectrometer equipped with a 50-m glass capillary column, wall-coated with OV-225, was used. G.1.c. conditions: temperature programme, 150” for 2 min, + 180’ at 5 ‘/mm, 180 o for 20 min; helium carrier gas at 1.5 mL/min; split ratio, l/10; sample volume, 1 pL;
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H. SCHWEER
2 injection
port,
,ubar, and emission
250”; separator,
in the forepump, current,
0.7 mA;
m/z 200-+800, scanned
220”. Ms.
conditions:
37 ,ubar; electron voltage
energy,
of the secondary
pressure
in c.i. source, 390
I50 eV; ion source, electron
multiplier,
220”;
1800 V;
in 2 s.
RESULTS AND DISCUSSION
C.i. mass spectrometry was preferred over the e.i. mode, because fewer fragment ions were formed and the spectra were more readily interpreted. The c.i. mode has the disadvantage that the relative intensities of fragment ions are dependent on the partial pressures of the reagent gas and the substrate’4.
LJ
t
10
c_
12
min
,
14
11
15
16
17 min
Fig. 1. Chromatograms of trifluoroacetylated O-butyloxime derivatives of the oxidation products of (a) ribitol, (b) D-arabinitoi, and (c) xylitol, using s.i.m. at m/z 606 (M t 1). Peak ~dentiti~: 1 and 6, D~-f~reO-2-~ntUlOSe; 2 and 3, AL-eryfhru-2-~entulose; 4, eryfhr~-3-~ntulose; 5, o-threo-3pentulose.
Fig. 2. Chromatograms of trifluoroacetylated O-butyloxime derivatives of 2-pentosuloses and 2,3and 2,4-pentodiuloses that are oxidation products of (a) ribitoi, (b) D-arabinitol, and (c) xylitol; s.i.m. at m/z 579 (M -t 1). Peak identities: 1 and 2, DL-erythuo-2-pentosulose; 2 and 6, obthreo-2pentosufose; 3,4,5, and 7, m-glycero-2,3and -2,4_pentodiulose.
G.L.C.-M.S. OF T~UOROACET~AT~
&WNLOXIMES
OF KETOSEfS
3
TABLE I MASS-SPECTRAL
m/z
648 607 606 605 575 492 436 420 380
DATA
OF ~~UOROAC~~D
Assignment
M + 43 M + 1 (13C) M+l M M f 43 - 73 M+l-114 M+I - 56 - 114 M + 1 - 73 - 113 M+l--2x113
&WTYL5XIME
DERNATfVES
OF PENTULOSES’
Relative intensity (%)
ox,-erythro-
DL-three
erythro-
D-th@O-
~-Pe~t~lose
2-Pe~t~~ose
3-Pent~lose
3-Pe~t~Io~e
i
2
1
2
1 20 100 46 1 8 4
4 20 100 20 2 28 I 1 8
2 20 100 35 1 12 2
4 20 100 21 4 79 1 6 5
13
8
2: loo 46
1 20 loo 16
27 14
19 8
56
21
DPressure of methylpropane in the ion source, 390 ,ubar; concentrations of pentuloses in derivative solutions @gj@,): DL-erythro-%pentulose, 0.73; DL-three-%pentdose, 1.30; erythro3-pentdose, 0.41; D-tkre53-pen&dose, 0.54.
Fig. 1 shows the chromatograms of trifluoroacetylated 0-butyloxime derivatives of pentuloses [selected ion monitoring (s.i.m.) at na/z 606 (M + l)]. The advantage of s.i.m. is that interference by derivatives of other oxidation products or unchanged pentitols is avoided. Oxidation of the pentitols gave the expected pentuloses. The most intense peak in the mass spectra of the pentulose derivatives had m/z 606 (M + 1) (Table I). The addition of C,H,+ (57 m.u.)2*4, the predominant ion of isobutanel’, could not be observed; however, the addition of C&H; (43 mu,> occurred. The (M + C4Hs)’ ion lost O-C,H; (73 m.u.>. In some spectra, the peak at m/z 492 was the second most intense and resulted from the loss of F,C-COOH (114 mu,) from (M + IIf. Moreover, mass differences of 56 (C,Hs) and 113 (F,C-COO.) occurred, resulting in peaks with rnfz 436 (M + 1 - 56 - 114), 420 M + 1 - 73 - 113), and 380 (M + 1 - 2 x 113). Peaks for the molecular ion M ’ were found in all spectra and were not formed by e.i. ionisation. M+ can arise by charge transfer from fluorine substituents to the reagent gas or the helium-isobu~ne mixture. The amounts (l-5%) of 2-pentosuloses and 2,3- and 2,4pentodiuloses also formed were too small to allow useful mass spectra to be obtained. Fig. 2 shows the chromatograms of the Zpentosuloses and 2,3- and 2,4-pentodiulose derivatives [s,i.m. at q’z 579 (M + l)]. Comparison with the retention times of Zpentosuloses, obtained by oxidation of D-ribose and D-xylose with Cu@I) acetate, allowed peaks 1, 2, and 6 to be assigned to It-pentosuloses. The other peaks, which occur in all chromatograms, could be due to DL-g@ceto-2,3- and -2,4-pentodiulose derivatives.
H. SCHWEER
4
b
12
13
15
16
min
17
18
19
20
21 min
Fig. 3. ~omato~ams of t~flnoroa~tylat~ 0-butyloxime derivatives of the oxidation products of (a) abitol, (6) D-ahritol, (c) D-glucitol, (d) D-mannitol, (e) D-iditol, and Lf) g&actitol; s.i.m. at m/z 732 (M + 1). Peak identities: 1 and 5, D-fructose; 2 and 3, DL-psicose; 4 and 5, or.-sorbose;, t and 14, ~r~hj~#-3-bexulose; 7 and 11, DL-r&o-3-hexulose; 9 and 13, Dt-tagatose; 10 and 16 DL-xylo-3-hexulose; 12 and IS, D-iyxo3-hexulose. Fig. 4. Chromatograms of trifluoroacetylated O-butyloxime derivatives of 2,Shexodiuloses that are oxidation products of (a> a&to& (6) D-ahritol, (c) D-gIUCitOi,(d) D-mannitol, (e> Diditof, and (f) galactitol; s.i.m. at m/z 705 (M i- 1). Peak identities: 1, 3, and 5, ettvtt2ru-2,5-h~odiulose; 2,4, and 6, DL-~~reo-2,S-hexodiulose. Theoretically, hindrance,
diulose
probably
overlapped
those
can give four
not all O-alkyloxime
Of the hexulose fluoroa~tylated
O-alkyloximes
derivatives,
DL-xyfo-3-hex&se
peaks,
because
of
steric
derivatives were formed.
only the mass spectrum 0-butyloxime
of the corresponding
but,
derivatives
of the first peak of tri-
could not be recorded, of rrL-tagatose
because it
(first peak)
and
OF TRD?L.UOROACETYLATED
M + 43 M + 1 (r3C) M+l M M + 1.5 - 126 M+l -113 M+ 1 - 114 M - 114 M + 1 - 57 - 113 M + 15 - 98 - 126 M + 1 - 2 x 113 (13C) M+l-2x113 M - 2 x 113 M + 1 - 57 - 113 - 114 M + 15 - 2 x 113 - 126 M + 1 - 2 x 113 - 114 Mfl-4x113
Assignment
DATA
3 3 19 100 25 111 25 30 23
5 21 12 18 12 7
16 80 21 7 12 32 7
4 22 11 1 4
1 3
2 24 100 74 21 14 26 14 8
3 24 100 27 7 14 56 35 2
12
24 100 35 20 24 77 44 19 1 18 95 25 6 17 42 14
2
DL-Sorbose
17 87 20 8 7 31 4
24 100 40 15 9 28 7
12 3
8 44 12 3 5 16 3
25 100 25 13 12 41 12 2 19 100 24 3 9 23 8
1 4 19 10 3 3 13 4 3
12
18 100 22 3 8 17 12
4 17 10 2 2 10 4 3
DL-Tagatose DL-ribo3-Hexulose
OF HEXULQSFS=
24 100 75 6 5 17 11 3 1 3 15 6
2
12
12
14 58 33 19 17 10 7 5 4 20 100 25 4 26 25 19
D-Fructose
DERIVATIVES
DL-Psicose
O-BUTYLOXME
6 23 6 3 4 16 4 5 20 19 100 23 5 6 25 5
1 19 77 58 3 7 27 18 7 3 20 100 22 5 5 12 5
6 26 7 3 6 21 7 5 3 18 100 24 6 9 28 11
12 1 11 45 11 4 9 38 12 7 10 19 100 25 7 4 25 4
3-Hexulose
3-Hexulose I2
D-lyxo-
D-arabino-
12
11.4;
10
13 66 30 8
25 100 39 4 18 77 40 9
3-Hexulose
DL-XylO
@Pressure of methylpropane in the ion source, 390 ybar; concentration of hexuloses in derivative solutions @g/pL): DL-psicose, 0.74; D-fructose, Dr.-sorbose, 1.78; DL-tagatose, 4.78; DL-ribo-3-hexulose, 1.39; D-arubino-3-hexulose, 1.43; D-lyxo-3-hexulose, 1.91; DL-xylo-3-hexulose, 3.09.
132 731 620 619 618 617 562 522 507 506 50.5 448 394 392 280
114 733
m/z
MASS-SPECTRAL
TABLE II
6
SCHWEER
H.
TABLE III MASS-SPECTRAL
m/z
DATA
OF TRIFLUOROACETYLATED
0-BUTYLOXIME
DERIVATIVES
Relative intensity (7;)
Assignment
erythro-2,5-Hexodiulose ____ 2 3 1 706 705 704 593 592 591 519 480 479 478 407 367
OF 2,hEXODIUWSES”
27 100 57 24 17 14 4 15 70 19 6 11
27 100 52 31 23 10 3 21 95 24 7 19
M -5 1 (13C) Mt-1 M + 15 126 M + 1 - 113 Mfl -114 M + 1 - 73 - 113 Mt l-2 x 113(13C) M-k-2x113 M-2x113 M + 15 - 73 - 113 - 126 M -i- 15 - 2 x 113 - 126
M
DL-three-2,S-Hexodiulose
27 100 53 24 19 16 5 20 90 25 9 16
I
2
3
26 100 61 19 16 15 1 6 27 8 2 2
26 100 56 14 14 27 3 6 28 8 2 2
26 100 57 14 16 39 3 8 39 11 3 2
_ @Pressure of methylpropane in the ion source, 390 itbar; concentration of 2,5-hexodiuloses derivative solutions (pug//CL):erythuo-2,5-hexodiulose, 1.17; DL-fhreo-2,5-hexodiulose, 10.8
in
D-Vito-3-hexulose (second peak) (Fig. 3), which are oxidation products of galactitol and D-glucitol. The mass-spectral data of the other hexuloses and the two 2,Shexodiuloses are shown in Tables II and III. The fragmentation patterns of hexulose and pentulose derivatives are quite similar. Most fragment ions result from loss of C,H; (57 m.u.),
i H-C-O-CA
I I
-3
-0
.0---x
I
O
CF3
Ii--!-O-5
-0 /-CF3
H-c-o-c*
0
I
/CFJ
C--N
3
+,y ,CFJ
.O
-H-c-o-c~O 126 m ”
-0
H-C-O--C/ H-c-o-cc
M
+
_
“C-_CF 96
1
3
H’
.CF3
H-c-o-c
mu
A-J
H-c-o-c
-0 ,CFJ
CFa
“-C-O-C
CFJ
H-C-O-C*
'"0
‘0-x
c-0
-0 /-I
0
0 ?
? 15
H\C_yy
.0---x
H-C-O-C.
0
! t-4 +
/
/-CF)
H-4--0---C~
H-c-o-c*
H\
+/y
C--N
15-126
M +
15-126-98
G.L.c.-M.S. OF TRIFLUOROA~ETYLATED O-BUTYLOXIME~ OF KETOSES
7
F,C-COO. (113 m.u.), and F,C-COOH (114 m.u.). The peaks with m/z 620, 522, and 394 cannot be explained by this fragmentation, and a possible origin is shown in Scheme 1. The CH: ion may be derived from isobutane, possibly by the addition of &Hz followed by the loss of C,H,. Fig. 4 shows the chromatograms of trifluoroacetylated O-butyloxime derivatives of 2,5-hexodiuloses [s.i.m. at m/z 705 (M + I)]. In the mass spectra, the peak at (M + 1) always predominated. Most fragment ions result from the loss of 0-C,H; (73 m.u.), F,C-COO. (113 m.u.), and F,C-COOH (114 m.u.). The peaks at m/z 593, 407, and 367 can be explained by analogy with the hexuloses, by addition of CH: (15 m.u.) and subsequent loss of CHO-COCF, (126 m.u.), 0-C,H;, and F,C-COO,. ACKNOWLEDGMENTS
Professor P. Decker is thanked for helpful discussions, and Mrs. A. Biithe and Dr. W. Heidmann for technical assistance with g.l.c.-m.s. This work was supported by the Stiftung Volkswagenwerk. REFERENCES 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
P. DECKERAND H. SCHWEER, J. Chromatogr.,236 (1982) 369-373. H. SCT-NEER, J. Chromatogr., 236 (1982) 355-360. P. DECKERAND H. SCHWEER, J. Chromatogr., 243 (1982) 372-375. H. SCXWEER,J. Chromatogr., 236 (1982) 361-367. P. DECKERAND H. SCHWEER,Curbohydr. Res., 107 (1982)l-6. P. DECKER, R. POHLMANN, AND C. A. WEBER-SCHILLING,Hoppe-Seyler’s 2’. Physiol. Chem., 356 (1975) 225. P. DECKERAND A. SPEIDEL,Z. Nuturforsch., Teil B, 27 (1972) 257-263. P. DECKER,H. SCHWEER,AND R. POHLMANN,J. Chromatogr., 244 (1982) 281-291. W. FUNCKE AND C. VON SONNTAG,Curbohydr. Res., 69 (1979) 247-251. F. R. SEYMOUR,E. C. M. CHEN, AND J.E. STOUFFER, Curbohydr. Res., 83 (1980) 201-242. R. A. LAINEI AND C. C. SWEELEY,Curbohydr. Res., 27 (1973) 199-213. G. PETERSSON, Carbohydr. Res., 33 (1974) 47-61. L. L. SALOMON,J.J.BURNS, AND C. G. KING, J. Am. Chem. Sot., 74 (1952) 5161-5162. R. A. HANCOCK, R. WALDER,AND H. WEIGEL,Org. Muss Spectrom., 14 (1979) 507-511. CI/GC-MS Brochure, Finnigan Corp., Sunnyvale, CA, 1973.