The 1H and 13C NMR spectra of
substituted benzaldehyde peracetyled -
lactosyl)thiosemicarbazones have been
studied and discussed. The magnetic
signals in their NMR spectra show the
relationships between the structural
features and positions of the substituted
groups in benzene ring.
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68
ANALYSIS OF NMR SPECTRA OF BENZALDEHYDE HEPTA-O-ACETYL--
LACTOSYL
Đến tòa soạn 25 - 4 - 2013
Nguyen Đinh Thanh
Faculty of Chemistry, College of Science, Hanoi National University
Hoang Thị Kim Van
Trường Đại học Công nghiệp Việt Trì (Phú Thọ)
TÓM TẮT
PHÂN TÍCH PHỔ NMR CỦA CÁC BENZALDEHYD HEPTA -O-ACETYL--
LACTOSYL THIOSEMICARBAZON
Phổ 1H và 13C NMR của các benzaldehyd (peracetyl--lactosyl)thiosemicarbazone đã
được thảo luận. Các tín hiệu cộng hưởng từ trong phổ NMR của chúng chỉ ra mối quan
hệ giữa cấu trúc và vị trí của nhóm thế theo tương quan Hammett. Cấu hình của các
thiosemicarbazone này được xác nhận dựa vào hằng số ghép cặp J = 9.0–8.5 Hz giữa
proton NH-4 của liên kết thiosemicarbazon và proton H-1’ trong hợp phần lactosyl.
INTRODUCTION
The synthetic method of hepta-O-acetyl-
-lactosyl-thiosemicarbazones has been
reported previously using microwave-
assisted method [1]. In previous articles
we announced the synthesis and
properties of another aldehyde/ketone
glycosyl per-O-acetylated
thiosemicarbazones [2]. There are several
discussions herein about the influence of
structural factors to the positions of
resonance signals in their
1
H and
13
C
NMR spectra of hepta-O-acetyl--
lactosyl)-thiosemicarbazones of
benzaldehydes and acetophenones.
EXPERIMENTAL PART
Substituted acetophenone hepta-O-
acetyl--lactosyl thiosemicarbazones 1
(Scheme 1) were synthesized in bellow
procedure [1]. Their
1
H and
13
C NMR
spectra was recorded on FT-NMR
Avance AV500 Spectrometer (Bruker,
Germany) at 500.13 MHz and 125.76
MHz, respectively, using DMSO-d6 as
solvent and TMS as an internal standard.
Spectral data of
1
H and
13
C NMR were
summarized in Tables 1 and 2.
Tạp chí phân tích Hóa, Lý và Sinh học – Tập 19, Số 2/2014
69
General procedure for substituted
benzaldehyde (hepta-O-acetyl--
lactosyl)-thiosemicarbazones (3LB a-v).
A mixture of hepta-O-acetyl--maltosyl
thiosemicarbazide 1L (1 mmol),
benzaldehyde 2a-v (1 mmol), glacial
acetic acid (0.5 ml) in absolute ethanol
(in the presence of glacial acetic acid as
catalyst) or glacial acetic acid (20 ml)
was heated at reflux using domestic
microwave oven TIFANY 750W in 5-7
min. The solvent was evaporated to one
half the original volumes. The resulting
colorless crystals were filtered by
suction. The crude product when
recrystallized from 96% ethanol to afford
the title compounds 3 LB a-v.
RESULTS AND DISCUSSION
The selected
1
H and
13
C
NMR spectral
data of benzaldehyde hepta-O-acetyl--
lactosyl thiosemicarbazones 3LB a-v
were listed in Table 1 and 2. From Tables
1 and 2 it’s shown that protons and
carbon-13 atoms in these molecules have
proper resonance signals in coresponding
spectral regions which are characteristic
for each atom type.
Protons in NH-2 and NH-4 groups have
signal at =12.18–11.67 ppm (singlet)
and =8.88–8.06 ppm (doublet, J=9.5–
9.0 Hz), respectively. Proton of
azomethin group (CH=N) shows
chemical shift at =8.53–8.00 ppm
(singlet). Aromatic protons have
resonance signals in region at =8.33–
6.27 ppm, and the multicity of these
signals depend on substituted patterns in
benzene rings. Protons in CH3 group in
acetate functions have signals in region at
=2.06–1.92 ppm. Protons of
disaccharide component have signals
including in range from 5.90 ppm to 3.93
ppm. Protons on C-1” and C-2” carbon in
pyranose ring A magnetically interact
each to other with coupling constant, in
this case,
3
J = 8.0–7.0 Hz that indicated
that these both protons on C-1” and C-2”
positions have trans-type interaction.
This one comfirm that linkage between
two pyranose rings, glucopyranose and
galactopyranose, in this disaccharide is
-(1→4)-glycoside bond that completely
agree with the structure of -lactose. The
distinct stucture pattern of
galactopyranose ring, compared with the
one of glucopyranose ring, is confirmed
by coupling constant between H-4” and
H-3” protons with 3J=3.75–2.5 Hz in
galactopyranose ring, compared with the
coupling constant
3
J=9.75–9.25 Hz in
glucopyranose ring. Protons on C-1’ and
C-2’ carbon atoms in ring B have similar
interaction with coupling constant
3
J=9.0–8.5 Hz, in relation to H–H
interaction of trans type, therefore,
thiosemicarbazide linkage group is
equatorial direction, i.e. all benzaldehyde
hepta-O-acetyl--lactosyl
thiosemicarbazones 3LB a-v have -
anomeric configuration [4]. Other
subrituents (hydroxy, methyl or methoxy)
70
also have specificsignals. The
13
C-NMR
spectra of compound 3LB a-v showed
the regions at 179.1–177.3 ppm (C=S),
170.2–169.0 ppm (C=O ester), 144.1–
138.9 ppm (azomethine CH=N), 146.4–
122.9 ppm (aromatic carbon atoms),
100.1–60.9 ppm (carbon atoms in lactose
component), and 21.2–20.1 ppm (methyl
carbon atoms in acetate groups). (Table
3).
O
O
AcO
AcO
AcO OAc
O
NH
4
OAc
AcO
OAc
C
3
NH
2
NH2
1
S
+
O
HR
1L
2B a-v
3LB a-v
EtOH solv., aceitc acid cat.,
MW oven
4"
5"
O
1"
2"
3" OAc
AcO
OAc
6"
OAc
4'
5'
O
1'
2'
3' OAc
AcO
O
6'
OAc
NH
4
C
3
NH
2
N
1
S
C
2'" 3'"
4'"
6'" 5'"
R
1
R
2
ring Aring B
1'"
where, R = 4-NO
2
(3B-a), 3-NO
2
(3B-b), 2-NO
2
(3B-c), 4-F (3B-d), 2,4-diCl (3B-e), 4-Cl (3B-f), 3-Cl (3B-g),
2-Cl (3B-h), 4-Br (3B-i), 2-OH-5-Br (3B-j), H (3B-k), 4-Me (3B-l), 4-iPr (3B-m), 4-OMe (3B-n),
3-OMe (3B-o), 2-OMe (3B-p), 4-OH (3B-q), 3-OH (3B-r), 2-OH (3B-s), 3-OMe-4-OH (3B-t),
3-OEt-4-OH (3B-u), 4-NMe
2
(3B-v).
Scheme 1. Synthesis of benzaldehyde (hepta-O-acetyl--lactosyl)thiosemicarbazones.
The
1
H13C long-ranged interaction in HMBC spectrum of thiosemicarbazone molecule
3LB-r is shown in scheme bellow:
4" 5" O
1"2"
3"
OAc
AcO
AcO
6"
OAc
4' 5' O
1'
2'
3'
OAc
AcO
O
6'
OAc
NH
4
C
3
NH
2
N
1
S
C
2'"
3'"
4'"
6'" 5'"
H
H
H
H
H
H
H
H
H
H
H
H O
H
HH
CH3
3LB-r (R=3-OMe):
Homonuclear
1
H–1H interactions in
COSY spectrum in compound 3LB-r are
as follows:NH-2(11.95)H-
1’(5.79)H-2’(5.19)H-3’(5.31)H-
4’(3.81)H-5’(3.88)H-6’b(4.07)H-
6’a(4.30); H-1”(4.79)H-2”(4.88)H-
3”(5.15)H-4”(5.24); H-5”(4.24)H-
6”a(4.03) và H-6”b(4.03); H-
2’”(7.44)H-5’”(7.34) và H-6’”(7.31);
H-4’”(7.00)H-5’”(7.34). The positions
of resonance signals of protons NH-2,
NH-4 and CH=N in compounds 3LB a-v
(Fig. 2 A, B and C) had linear regression
expressions as follows, respectively:
NH-2 = 0.298 + 11.903 (R
2
= 0.96)
NH-4 = 0.308 + 8.621 (R
2
= 0.93)
CH=N = 0.145 + 8.065 (R
2
= 0.77)
71
Table 1. Selected
1
H NMR spectra of substituted benzaldehyde (hepta-O-acetyl--lactosyl)thiosemicarbazones
[ (ppm), multicity, J (Hz)]
R 4-NO2 3-NO2 4-F 4-Cl 3-Cl 4-Br H
Proton 3LB-a 3LB-b 3LB-d 3LB-f 3LB-g 3LB-i 3LB-k
NH-2 12.16,s 12.10,s 11.90,s 11.95,s 11.99,s 12.00,s 11.95,s
NH-4 8.88,d,9.0 8.83,d,9.0 8.66,d,9.0 8.70,d,9.0 8.75,d,9.0 8.70,d,9.0 8.67,d,9.5
CH=N 8.18,s 8.21,s 8.09,s 8.08,s 8.08,s 8.08,s 8.10,s
H-2’” 8.10,d,9.0 8.58,s 7.88,d,5.5,8.5 7.85,d,8.5 7.98,s 7.82,d,8.5 7.82–7.80,m
H-3’” 8.25,d,9.0 - 8.10,d,8.5 7.49,d,8.5 – 7.66,d,8.5 7.45–7.43,m
H-4’” – 8.30,d,7.5 – – 7.48–7.44,m – 7.45–7.43,m
H-5’” 8.25,d,9.0 7.72,t,8.0 8.10,d,8.5 7.49,d,8.5 7.48–7.44,m 7.66,d,8.5 7.45–7.43,m
H-6’” 8.10,d,9.0 8.24,dd,1.5,8.0 7.88,d,5.5,8.5 7.85,d,8.5 7.70,dd,7.0,1.5 7.82,d,8.5 7.82–7.80,m
H-1’ 5.88,t,9.0 5.86,t,9.0 5.85,t,9.25 5.85,t,9.0 5.85,t,9.0 5.90,t,9.0 5.86,t,9.25
H-2’ 5.24–5.21,m 5.20,t,9.5 5.19,1H,9.25 5.20,t,9.25 5.21,t,9.25 5.24,t,9.25 5.19,t,9.5
H-3’ 5.31,t,9.25 5.31,t,9.0 5.30,d,9.25 5.30,t,9.25 5.30,t,9.0 5.33,t,9.25 5.31,t,9.25
H-4’ 3.81,t,9.25 3.82,t,9.25 3.81,t,9.5 3.80,t,9.5 3.81,t,9.5 3.84,t,9.75 3.80,t,9.5
H-5’ 3.90–3.87,m 3.91–3.84,m 3.90–3.87,m 3.90–3.88,m
3.89,ddd,
1.5,5.5,10.0
3.84,t,9.75
3.89,ddd,
1.75,5.75,9.75
H-6’a 4.31,d,11.5 4.31,d,11.0 4.31,d,11.5 4.30,d,11.5 4.31,d,11.0 4.33,d,11.0 4.30,d,11.0
H-6’b 4.07,dd,5.5,12.5 4.08,dd,5.5,12.0 4.07,dd,5.5,11.0 4.08–4.05,m 4.07,5.75,12.25 4.09,dd,5.5,12.0 4.07,dd,5.5,12.0
H-1” 4.80,d,8.0 4.80,d,8.0 4.80,d,8.0 4.80,d,7.5 4.80,d,8.0 4.83,d,8.0 4.80,d,8.0
H-2” 4.88,t,8.75 4.88,dd,8.25,10.25 4.88,dd,3.25,10.5 4.88,t,9.0 4.88,dd,2.0,8.0 4.91,dd,3.0,11.5 4.87,dd,3.0,10.0
H-3” 5.15,dd,3.5,10.0 5.15,dd,3.5,10.0 5.17,dd,3.75,9.75 5.16,dd,3.5,10.0 5.16,dd,3.5,10.0 5.16,dd,3.75,10.25 5.15,dd,3.5,10.5
H-4” 5.24–5.21,m 5.24,d,3.5 5.24,d,3.5 5.24,d,3.5 5.24,d,3.5 5.28,d,3.5 5.24,d,3.5
H-5” 4.25,t,6.5 4.25,t,6.75 4.25,t,6.5 4.25,t,6.0 4.25,t,6.75 4.29,t,6.5 4.26,t,6.75
H-6”a 4.03,d,6.0 4.03,dd,2.25,6.75 4.04–4.02,m 4.04–4.03,m 4.04–4.00,m 4.07–4.05,m 4.04,dd,2.25,6.25
H-6”b 4.03,d,6.0 4.03,dd,2.25,6.75 4.04–4.02,m 4.04–4.03,m 4.04–4.00,m 3.94–3.91,m 4.04,dd,2.25,6.25
COCH3 2.11–2.01 2.11–1.91 2.11–2.01 2.11–1.91 2.11–1.90 2.15–1.94 2.11–1.90
72
Table 1(continuing). Selected
1
H NMR spectra of substituted benzaldehyde (hepta-O-acetyl--lactosyl)thiosemicarbazones
[ (ppm), multicity, J (Hz)]
R 4-Me 4-iPr 4-OMe 3-OMe 4-OH 4-NMe2
Proton 3LB-l 3LB-m 3LB-n 3LB-o 3LB-q 3LB-v
NH-2 11.86,s 11.87,s 11.81,s 11.95,s 11.76,s 11.67,s
NH-4 8.59,d,9.5 8.57,d,9.0 8.55,d,9.0 8.62,d,9.0 8.51,d,9.5 8.41,d,9.5
CH=N 8.06,s 8.09,s 8.05,s 8.07,s 8.00,s 7.97,s
H-2’” 7.69,d,8.5 7.72,d,8.0 7.75,d,8.5 7.44,s 6.81,d,8.5 7.59,d,8.5
H-3’” 7.25,d,8.5 7.30,d,8.0 6.99,d,8.5 – 7.64,d,8.5 6.72,d,8.5
H-4’” – – – 7.00,dd,1.5,8.0 – –
H-5’” 7.25,d,8.5 7.30,d,8.5 6.99,d,8.5 7.34,t,8.0 7.64,d,8.5 6.72,d,8.5
H-6’” 7.69,d,8.5 7.72,d,8.0 7.75,d,8.5 7.31,t,8.0 6.81,d,8.5 7.59,d,8.5
H-1’ 5.84,t,9.0 5.83,t,9.25 5.83,t,9.25 5.79,t,9.0 5.83,t,9.25 5.82,t,9.0
H-2’ 5.21,t,9.25 5.18,t,9.5 5.18,t,9.25 5.18,t,9.25 5.18,t,9.25 5.17–5.14,m
H-3’ 5.30,t,9.25 5.30,t,9.25 5.30,t,9.0 5.31,t,9.25 5.30,t,9.25 5.30,t,9.0
H-4’ 3.81,t,9.5 3.81,t,9.25 3.82–3.79,m 3.81,t,9.0 3.89–3.86,m 3.81,t,9.25
H-5’ 3.90–3.87,m 3.88–3.87,m 3.89–3.87,m 3.88,ddd,3.5,5.5, 10.0 3.80,t,9.75 3.88–3.85,m
H-6’a 4.30,d,11.0 4.30,d,11.5 4.30,d,11.5 4.30,d,11.0 4.30,d,11.0 4.30,d,11.0
H-6’b 4.07,dd,5.75,12.25 4.09–4.03,m 4.09–4.05,m 4.07,dd,12.5,6.75 4.06,dd,5.5,9.5 4.09–4.05,m
H-1” 4.80,d,8.0 4.80,d,8.0 4.80,d,7.5 4.79,d,7.5 4.80,d,8.0 4.79,d,7.5
H-2” 4.88,t,9.0 4.88,t,9.75 4.88,t,9.25 4.88,dd,10.0,3.0 4.87,dd,10.0,3.0 4.88,t,9.0
H-3” 5.15,dd,3.75,10.25 5.15,dd,10.5,3.75 5.15,dd,10.0,3.0 5.15,dd,10.5,3.5 5.16,dd,10.0,4.0 5.17–5.14,m,
H-4” 5.24,d,3.5 5.24,d,3.5 5.24,d,3.0 5.24,d,3.5 5.24,d,3.5 5.25,d,2.5
H-5” 4.25,t,6.5 4.25,t,5.75 4.24,t,6.75 4.24,t,6.75 4.25,t,6.75 4.25,t,6.0
H-6”a 4.04–4.03,m 4.09–4.03,m 4.04–4.03,m 4.03,d,6.5 4.03–4.02,m 4.04–4.03,m
H-6”b 4.04–4.03,m 4.09–4.03,m 4.04–4.03,m 4.03,d,6.5 4.03–4.02,m 4.04–4.03,m
COCH3 2.11–1.90 2.11–1.90 2.11–1.91 2.11–2.01 2.11–1.90 2.11–1.91
Other
protons
2.34,s,4’”-Me
2.92,q,7.0,4’”-CH(CH3)2;
1.21,d,7.0,4’”-CH(CH3)2
3.81,s,4’”-OMe 3.83,s,3’”-OMe 9.97,s,4’”-OH 2.97,s,6H,4’”-N(Me)2
73
Table 2. Selected
13
C NMR spectra of substituted benzaldehyde (hepta-O-acetyl--lactosyl)thiosemicarbazones, (ppm)
R 4-NO2 3-NO2 4-F 4-Cl 3-Cl 4-Br H 4-Me 4-iPr 4-OMe 3-OMe 4-OH 4-NMe2
Cacbon 3LB-a 3LB-b 3LB-d 3LB-f 3LB-g 3LB-i 3LB-k 3LB-l 3LB-m 3LB-n 3LB-o 3LB-q 3LB-v
C=S 178.8 178.7 178.4 178.3 178.6 178.4 178.3 178.2 178.2 177.8 178.4 177.7 177.3
COCH3
170.2–
169.0
170.2–
69.1
170.2–
169.1
170.5–
169.4
170.1–
169.0
170.2–
169.0
170.3–
169.1
170.2–
169.0
170.2–
169.0
170.5–
169.4
170.2–
169.0
170.2–
169.0
170.2–
169.0
CH=N 141.1 141.6 142.6 142.7 142.2 142.5 143.7 143.9 143.8 144.1 143.5 144.1 144.8
C-1’” 140.2 135.7 130.4 132.5 135.9 133.0 133.7 131.0 131.4 126.0 135.1 124.6 120.8
C-2’” 128.4 121.9 129.7 129.8 126.3 129.4 128.7 127.5 127.6 129.2 111.4 129.4 128.9
C-3’” 123.8 148.4 115.7 128.8 133.7 131.7 127.6 129.3 126.6 114.2 159.6 115.6 111.6
C-4’” 147.8 124.4 163.3 134.9 130.5 123.5 130.3 140.2 150.9 161.1 116.5 159.6 151.7
C-5’” 123.8 130.2 115.7 128.8 129.8 131.7 127.6 129.3 126.6 114.2 129.6 115.6 111.6
C-6’” 128.4 133.4 129.7 129.8 126.7 129.4 128.7 127.5 127.6 129.2 120.7 129.4 128.9
C-1’ 81.3 81.3 81.3 81.2 81.3 81.2 81.2 81.2 81.1 81.1 81.2 81.1 81.1
C-2’ 71.2 71.1 71.1 70.9 71.1 71.1 71.1 71.1 71.0 70.9 70.9 71.1 71.0
C-3’ 72.8 72.7 72.7 72.6 72.7 72.7 72.7 72.7 72.7 72.6 72.5 72.7 72.7
C-4’ 76.0 76.0 76.0 75.9 76.0 76.0 76.1 76.0 76.0 75.9 76.1 76.1 76.1
C-5’ 73.4 73.5 73.4 73.5 73.4 73.4 73.3 73.4 73.4 73.5 73.4 73.3 73.4
C-6’ 62.4 62.4 62.4 62.2 62.3 62.4 62.4 62.3 62.3 62.2 62.3 62.3 62.3
C-1” 99.6 99.6 99.6 99.6 99.6 99.6 99.6 99.6 99.6 99.6 99.6 99.6 99.6
C-2” 68.9 68.9 68.9 68.8 68.9 68.8 68.8 68.9 68.8 68.8 68.8 68.8 68.9
C-3” 70.4 70.4 70.4 70.3 70.4 70.4 70.4 70.4 70.3 70.3 70.4 70.3 70.4
C-4” 67.1 67.1 67.1 67.0 67.1 67.1 67.1 67.1 67.1 67.1 67.1 67.1 67.1
C-5” 69.7 69.8 69.8 69.7 69.7 69.7 69.7 69.7 69.7 69.7 69.7 69.7 69.7
C-6” 61.0 61.0 61.0 60.9 61.0 60.9 61.0 60.9 60.9 60.9 60.9 60.9 60.9
COCH3
20.7–
20.3
20.7–
20.3
20.7–
20.2
20.5–
20.1
20.8–
20.2
20.7–
20.4
20.7–
20.3
20.6–
20.2
20.6–
20.2
20.5–
20.1
20.6–
20.2
20.7–
20.3
20.6–
20.2
Note: Other (13C): 21.0,4’”-Me (3LB-l); 33.4.5,4’”-CH(Me)2; 23.5,4’”-CH(Me)2 (3LB-m);
55.2,4’”-OCH3 (3LB-n); 55.2,3’”-OCH3 (3LB-o); 40.0,4’”-N(Me)2 (3LB-v).
74
Conversely, carbon atom in imine group
were affected clearly by these
substituents with opposite trend: the
donating ones (with < 0, such as 4-OH,
4-OMe, 4-Me on benzene ring of
benzadehyde) caused signal to be shifted
to upfield region, and the withdrawing
ones (with < 0, such as 3-NO2-4-Cl, 4-
NO2, 3-NO2-4-Me, 3-NO2-4-OMe, 4-Cl,
4-Br in benzadehyde series) caused the
resonance of this carbon atom to be in
downfield region (Table 3). These
tendencies could be shown in equations
as follows (Fig. 2D).
CH=N = 2.458σ + 143.31 (R
2
= 0.91)
Figure 2. Linear relationships between NH-2 (A), NH-4 (B), CH=N (C) và C=N (D) and
Hammett’s in compouds 3LBa-v
CONCLUSIONS
The
1
H and
13
C NMR spectra of
substituted benzaldehyde peracetyled -
lactosyl)thiosemicarbazones have been
studied and discussed. The magnetic
signals in their NMR spectra show the
relationships between the structural
features and positions of the substituted
groups in benzene ring.
75
Acknowledgments. Financial support
for this work was provided by Vietnam's
National Foundation for Science and
Technology Development (NAFOSTED).
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