Simple and efficient one-pot solvent-free synthesis of N-methyl imines of aromatic aldehydes

Article abstract of DOI:10.1016/j.crci.2013.01.010

A one-pot solvent-free synthesis of N-methyl imines in good to excellent yields was performed by grinding together aromatic aldehydes and methylamine hydrochloride in the presence of a base. The best yields were achieved when an excess of methylamine hydrochloride and inexpensive sodium hydrogen carbonate was used (usually in a molar ratio ArCHO/CH₃NH₂· HCl/NaHCO₃ = 1:5:5), allowing the reaction to proceed for 1 h (in the case of aromatic aldehydes containing electron-withdrawing substituents) or overnight (in the case of electron-rich aldehydes). After a simple work-up (extraction with diethyl ether) the obtained products were mostly pure enough for spectral characterization. In this way, 31 N-methyl imines were prepared, among which eight were synthesized for the first time. Their structures were elucidated by spectral means (¹H- and ¹³C-NMR, IR, MS) whenever it was possible. In the case of salicylaldehyde and 4-chlorobenzaldehyde, the synthesis of the corresponding imines was also conducted on a gram-scale with a 72% and 84% isolated yield, respectively. The present approach not only provides good to high yields, but also eliminates the disadvantages of the traditional synthesis of N-methyl imines, such as the use of hazardous solvents and more or less expensive catalysts and the necessity of work/handling with an anhydrous gas in pressurized containers.

Full text of DOI:10.1016/j.crci.2013.01.010

C. R. Chimie 16 (2013) 257–270
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´
Full paper/Memoire
Simple and efficient one-pot solvent-free synthesis of N-methyl imines
of aromatic aldehydes
a,
a
b
*
´
´
´
´
Niko S. Radulovic , Ana B. Miltojevic , Rastko D. Vukicevic
a
ˇ
ˇ
ˇ
Department of Chemistry, Faculty of Science and Mathematics, University of Nis, Visegradska 33, Nis, 18000, Serbia
b Department of Chemistry, Faculty of Science, University of Kragujevac, R. Domanovic´a 12, Kragujevac, 34000, Serbia
A R T I C L E I N F O
A B S T R A C T
Article history:
A one-pot solvent-free synthesis of N-methyl imines in good to excellent yields was
performed by grinding together aromatic aldehydes and methylamine hydrochloride in
the presence of a base. The best yields were achieved when an excess of methylamine
hydrochloride and inexpensive sodium hydrogen carbonate was used (usually in a molar
ratio ArCHO/CH3NH2ÁHCl/NaHCO3 = 1:5:5), allowing the reaction to proceed for 1 h (in the
case of aromatic aldehydes containing electron-withdrawing substituents) or overnight
(in the case of electron-rich aldehydes). After a simple work-up (extraction with diethyl
ether) the obtained products were mostly pure enough for spectral characterization. In
this way, 31 N-methyl imines were prepared, among which eight were synthesized for the
first time. Their structures were elucidated by spectral means (1H- and 13C-NMR, IR, MS)
whenever it was possible. In the case of salicylaldehyde and 4-chlorobenzaldehyde, the
synthesis of the corresponding imines was also conducted on a gram-scale with a 72% and
84% isolated yield, respectively. The present approach not only provides good to high
yields, but also eliminates the disadvantages of the traditional synthesis of N-methyl
imines, such as the use of hazardous solvents and more or less expensive catalysts and the
necessity of work/handling with an anhydrous gas in pressurized containers.
Received 16 November 2012
Accepted after revision 15 January 2013
Available online 7 March 2013
Keywords:
Aromatic aldehydes
Methylamine hydrochloride
N-methyl imines
One-pot synthesis
Solvent-free
´
ß 2013 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.
1. Introduction
economy and low cost. The various successful solvent-free
organic reactions based on grinding two reactants together
The development of environmentally benign methods
in synthetic organic chemistry is of great interest, as
ecological concerns increase. One of the most important
goals in ‘‘green chemistry’’ is the elimination of volatile
organic solvents [1]. Solvent-free organic reactions have
captured great interest not only because of their immense
ecological importance, but also because they offer many
synthetic advantages in terms of high efficiency, yield,
selectivity, simplicity of the reaction procedure, mild
conditions, reduction of waste [2], as well as their safety,
at room temperature has been previously reported for
aldol condensations [3], Dieckmann condensations [4],
Biginelli reactions [5], Grignard reactions [6], Knoevenagel
condensations [7,8], Reformatsky reactions [9], cyclopro-
panation reactions [10], oxidations [11], reductions [12],
oximation of carbonyls [13], and rearrangement reactions
[14]. Although, the potential of solvent-free methodologies
based on grinding reactants together has started to
emerge, there is still great need for exploring it [15].
On the other hand, imines have enormous application
in organic and medicinal chemistry. Thus, they are
important intermediates in reactions, such as the synthesis
of secondary amines (by hydrogenation) [16], the forma-
* Corresponding author.
tion of optically active a-alkyl aldehydes [17], nucleophilic
additions of organometallic reagents [18], enantioselective
oxidations (chiral oxaziridines) [19], cycloadditions
E-mail addresses: nikoradulovic@yahoo.com,
vangelis0703@yahoo.com (N.S. Radulovic´), anamiltojevic@yahoo.com
(A.B. Miltojevic´), vuk@kg.ac.rs (R.D. Vukic´evic´).
1631-0748/$ – see front matter ß 2013 Acade´mie des sciences. Published by Elsevier Masson SAS. All rights reserved.
http://dx.doi.org/10.1016/j.crci.2013.01.010

258
N.S. Radulovic´ et al. / C. R. Chimie 16 (2013) 257–270
[20,21], as well as in the synthesis of pharmaceutically
significant compounds, like -lactams [22–27]. Moreover,
used as a learning set to determine the optimal conditions
of the solvent-free synthesis of N-methyl aromatic imines
(Scheme 1). These parameter-ranging experiments includ-
ed variation of reaction time, reagent stoichiometry and
the type of base used.
b
it is well known that they possess a wide spectrum of
biological activities; they act as lipoxygenase inhibitors,
anti-inflammatory agents [28] and anti-cancer agents [29–
31]. Due to their fascinating pharmacological and thera-
peutic properties, as well as their great use in organic
synthesis, the development of simple, efficient and
environmentally friendly synthesis of imines is of great
importance.
We began our study by evaluating the influence of the
reaction time and reagent ratio on the yield of N-(2-
nitrobenzylidene)methanamine.
Initially,
equimolar
amounts of o-nitrobenzaldehyde, CH3NH2ÁHCl and
NaHCO3 were ground together for 10 min with a pestle
and the reaction mixture was left to stand at room
temperature for 30 min. The crude product turned out to
be a mixture of the aldehyde and imine in the ratio 36:64
Imines can be prepared by various methods, but the
most common one is probably the reaction of aldehydes
and ketones with amines, discovered by Schiff [32]. It
includes two general steps; the first one, nucleophilic
attack at the carbonyl carbon by an amine, is reversible,
and it is followed by the second step – removal of water –
which determines feasibility of imine formation [33].
Removal of water can be accomplished by azeotropic
distillation [34] (the first, traditional synthesis of imines,
originally reported by Schiff et al. [35]), using molecular
sieves [36], or dehydrating solvents such as tetramethyl
orthosilicate [37] and trimethyl orthoformate (in situ
dehydration strategy) [38,39]. Alternative approaches
include condensation reactions in the presence of Lewis
acids (ZnCl2 [40], TiCl4 [41–44], MgSO4–PPTS [45], alumina
[46], K-10 clay [39,47] and CaO under microwave
irradiation [48], Ti(OR)4 [49,50], CuSO4 [50], Mg(ClO4)2
[33]), which on, one hand, catalyze the amine nucleophilic
attack on the carbonyl group and, on the other, serve as
dehydrating agents in the final step. Microwave-assisted
solvent-free synthesis of N-substituted aldimines has been
recently reported by Paquin et al. [51].
There are several publications on the synthesis of N-
methyl imines. The classical methods involve the use of
aqueous solution of methylamine (which can be carried
out either in water [52,53] or in the mixture of water and
an organic solvent [54,55]), or the use of methylamine
hydrochloride as the methylamine source [55]. An
alternative way includes reaction of the appropriate
aldehyde with N,N-bis(trimethylsilyl)methylamine in the
presence of trimethylsilyl trifluoromethanesulfonate in
dichloromethane or dichloroethane [56]. Solvent-free
syntheses of N-methyl imines of aromatic aldehydes have
already been reported, but these procedures include the
use of either methylamine gas (overnight, at room
temperature) [57] or 1,3-dimethylurea dispersed on
montmorillonite K10 under microwave irradiation as the
methylamine precursors [51]. Therefore, these methods
have several inherent disadvantages, such as gas handling,
the requirement of organic solvents, long reaction times
and use of a catalyst. Herein, for the first time, we wish to
report the use of methylamine hydrochloride under mild
(based on
a gas chromatography–mass spectrometry
analysis), whereas the pure imine was isolated after
column chromatography (SiO2) in the 56% yield (entry 1,
Table 1). In order to improve the yield, the reaction was
carried out with a 2- and 5-fold excess of CH3NH2ÁHCl and
NaHCO3 and/or the reaction time was prolonged (to 1 and
2 h). As it can be seen from the data listed in Table 1, both of
these parameters considerably affected the yield. Thus, by
prolonging the reaction time to 1 and 2 h the yield
increased to 66 and 69%, respectively (entries 2 and 3,
Table 1), whereas the use of double amounts of
CH3NH2ÁHCl and NaHCO3 in the reaction showed almost
the same effect (entry 4, Table 1). However, the use of a 5-
fold excess of these reactants did not increase the yield
comparably to the preceding experiment (compare entries
4 and 5, Table 1). The best results (90%; see entry 6, Table 1)
were achieved when the reaction was performed by
grinding the reactants in the molar ratio aldehyde/
CH3NH2ÁHCl/NaHCO3 = 1:2:2 and allowing the reaction
mixture to stand for one additional hour at room
temperature.
The reaction completely failed when carried out
without a base, even when CH3NH2ÁHCl was used in a 5-
fold excess and the reaction mixture was allowed to stand
overnight at room temperature (in order to exclude a very
slow reaction; see entries 7 and 8, Table 1). In these
particular cases, no imine was formed and the total
amount of the starting aldehyde was recovered. Therefore,
the base plays a crucial role, apparently through liberating
methylamine from its salt (by neutralizing HCl), and we
decided to examine the influence of the type of the applied
base on the yield of this reaction, keeping in mind the
conditions achieving the highest yield when NaHCO3 was
used as the base (2-fold excess of base and CH3NH2ÁHCl
and a 1 h run). Triethylamine, sodium hydroxide and
potassium carbonate have been chosen for this purpose.
The obtained results are listed in Table 1 (entries 9, 10 and
11), and show that the best yield was obtained in the case
of K2CO3 (91%, entry 11, Table 1), and NaHCO3 (90%, entry
6, Table 1), probably because CO2, as one of the products of
their reactions with methylamine hydrochloride, leaves
the reaction mixture and drives the equilibrium of this
reaction in the desired direction. The poor reaction yield
when triethylamine was used (entry 9, Table 1), could be
explained by the less favourable thermodynamics of this
process (the driving force of the liberation of CO2 is
lacking). However, the same rationalization cannot be
applied to the reaction in which NaOH was used as the base
conditions as an efficient reagent in
a simple and
inexpensive one-pot solvent-free synthesis of N-methyl
imines from aromatic aldehydes.
2. Results and discussion
The data accumulated from the reactions conducted
with finely ground mixtures of 2-nitrobenzaldehyde and
methylamine hydrochloride with or without a base were

N.S. Radulovic´ et al. / C. R. Chimie 16 (2013) 257–270
259
Scheme 1. One-pot solvent-free synthesis of N-methyl imines of aromatic aldehydes.
(entry 10, Table 1), since there is no thermodynamic
impediment for the completion of this reaction. The lower
yield than expected in this case could be explained by the
fact that it readily liberates a large amount of gaseous
CH3NH2, which leaves the reaction mixture before having a
chance to react with the aldehyde. These findings
prompted us to continue our study with the less expensive
base, NaHCO3.
To investigate the scope of this reaction, various
aromatic aldehydes (with electron-withdrawing and/or
electron-donating substituents) were subjected to the
above mentioned reaction conditions. The reactivity of the
aldehydes followed the expected general trend of electro-
philicity (Table 2), i.e. it has been observed that the
aldehydes bearing electron-withdrawing groups gave
better yields in shorter reaction times and with lower
Table 1
The influence of reaction conditions and the base on the solvent-free imination of 2-nitrobenzaldehyde with CH3NH2ÁHCl at room temperature.
Entry
Base
Reagents ratio (aldehyde:CH3NH3Cl:base)
t (h)
Ratioa aldehyde:imine
Yieldb(%)
1
NaHCO3
1:1:1
1:1:1
1:1:1
1:2:2
1:5:5
1:2:2
1:5:0
1:5:0
1:2:2
1:2:2
1:2:2
0.5
36:64
23:77
22:78
24:76
29:71
2:98
56
66
69
68
66
90
0
2
1
3
2
4
0.5
5
0.5
6
1
7
None
2
100:0
100:0
53:47
3:97
8
Overnight
0
9
Et3N
1
1
1
40
77
91
10
11
NaOH
K2CO3
0:100
a
GC–MS ratio between peak areas.
b
Isolated yields of N-methyl imines.

260
N.S. Radulovic´ et al. / C. R. Chimie 16 (2013) 257–270
Table 2
Solventless imination of aromatic amines by CH3NH2ÁHCl in the presence of NaHCO3 as the base at room temperature.
Entry
1
Aldehyde
Reagents ratioa
Time (h)
1
Imine
Yield (%)b
80
1a
1:2:2
2
3
4
1b
1c
1:2:2
1:5:5
0.5
1
38
79
89
o.n
5
6
1:5:5
1
20
94
o.n
7
8
1d
1e
1:5:5
1:5:5
1
22
87
o.n
9
1
20
78
10
o.n
11
1af
1:5:5
1
85
12
13
1f
1:5:5
1:5:5
1:5:5
1
1
83
78
1g
1h
14
15
1
18
79
o.n
16
17
1i
1:5:5
1:5:5
1
32
80
o.n
18
1j
2
86
19
20
1k
1:5:5
1:5:5
1
41
60
o.n
21
22
1l
1:5:5
1:5:5
1
47
56
o.n
23
24
1m
1
43
51
o.n

N.S. Radulovic´ et al. / C. R. Chimie 16 (2013) 257–270
261
Table 2 (Continued)
Entry
25
Aldehyde
Reagents ratioa
Time (h)
1
Imine
Yield (%)b
1n
1:5:5
1:5:5
77
26
27
1o
1
48
84
o.n
28
29
30
31
32
1p
1q
1:2:2
1:5:5
1:5:5
1:5:5
1:5:5
1
33
51
65
75
73
1
3
o.n
2
33
34
1r
1:5:5
2
25
58
o.n
35
36
1s
1t
1:2:2
1:5:5
1
3
o.n
71
37
38
39
1:2:2
1
1
1
1:5:5
o.n
o.n
1:10:10
80
40
41
1u
1:5:5
2
48
82
o.n
42
43
44
1v
1w
1z
1:5:5
1:5:5
1:5:5
2
2
1
78
81
82
45
46
1x
1y
1:5:5
1
38
79
o.n
47
48
49
1:3:0
1:5:5
1:2:2
0.75
1
0
55
61
2

262
N.S. Radulovic´ et al. / C. R. Chimie 16 (2013) 257–270
Table 2 (Continued)
Entry
50
Aldehyde
Reagents ratioa
Time (h)
1
Imine
Yield (%)b
20
1aa
1:5:5
51
52
1ab
1:5:0
1:5:5
o.n
o.n
0
0
53
1ac
1ad
1ae
1:5:5
2
78
54
55
56
57
1:5:0
1:5:5c
1:5:1d
1:5:5
2
4
2
2
0
0
26
89
58
59
60
1:5:0
1:5:5
2
0
0
0
o.n
2
o.n: overnight.
a
Aldehyde/CH3NH3Cl/base
b
c
Isolated yields of N-methyl imines.
NaH2PO4 was used as a base.
Et3N was used as a base.
d
aldehyde to amine ratios than the ones with electron-
donating substituents. Specifically, among ortho-substi-
tuted aldehydes, o-nitrobenzaldehyde gave the highest
yield (entry 6, Table 1), whereas the yields of the aldehydes
with electron-releasing substituents in the ortho position,
such as 2-hydroxy- (entries 47–52, Table 2), 2-alkyloxy-
(entries 25, 32–34, 44–46, Table 2) or 2-acetoxybenzalde-
hydes (entry 43, Table 2) were lower but still better or
comparable than those of the corresponding meta- and
para-isomers (which is perhaps a consequence of the
higher electrophilicity of the ortho-isomers compared to
meta- and para- due to the displacement of the aldehyde
group from the plane of the aromatic core by the ortho-
substituent). Among the o-substituted aldehydes, the
poorest outcome was noted for salicylaldehyde (entries
47–49, Table 2), but a gas chromatography–mass spec-
trometry GC–MS) analysis revealed that the resulting
reaction mixture contains no starting aldehyde. This could
be explained by acidic properties of the phenolic group
(pKa = 8.37). During the grinding of salicylaldehyde with
CH3NH2ÁHCl and NaHCO3, the sodium salt of the aldehyde
is immediately formed as apparent from the yellow
coloration of the mixture. Deprotonation is expected to
slow down the reaction (–OÀ is a much more powerful
electron-donating substituent compared to –OH) and
make the work-up not as straightforward (a significant
share of the imine could, as well, be in the form of a salt
and, hence, that part would remain insoluble in ether). This
becomes more apparent for more acidic derivatives of
salicylaldehyde (3,5-dibromosalicylaldehyde and 5-nitro-
salicylaldehyde) that either give much lower yields of the
appropriate N-methyl imines or no imine at all (20 and 0%,
respectively) (entries 50–52, Table 2). The GC–MS analysis
revealed that in the case of 3,5-dibromosalicylaldehyde,
the resulting reaction mixture contained no starting
aldehyde, whereas in the case of 5-nitrosalicylaldehyde,
the reaction failed completely (aldehyde:imine ratio was
100:0, according to the corresponding peak areas ratio in
GC–MS chromatograms). On the other hand, the resulting
ortho-hydroxy imines are additionally stabilized by
intramolecular hydrogen bonding (perhaps this is the fact
that can provide some insight into the formation of the
imine of salicylaldehyde in general).
The yield of the reaction seems to be dependent on the
steric nature of the ortho-substituent as well. The
derivative with the sterically demanding ortho-hexy-
loxy-group gave noteworthy amounts of N-(2-(hexylox-
y)benzylidene)methanamine only after the reaction
mixture was left to stand overnight (entry 46, Table 2).
As expected, the aldehydes with para- positioned
electron-releasing substituents gave the poorest results
in this reaction. In the case of p-dimethylaminobenzalde-
hyde, the reaction failed and the total amount of the
starting aldehyde was recovered (entries 58–60, Table 2). A
quantitative synthesis of N,N-dimethyl-4-((methylimino)-
methyl)aniline from the corresponding aldehyde and
gaseous methylamine was, however, previously reported
[57]. This led us to consider the possibility that differing
rates of the reaction between p-dimethylaminobenzalde-
hyde and methylamine and the loss of methylamine gas
from the reaction mixture by evaporation might be the
reason why no imine was detected.

N.S. Radulovic´ et al. / C. R. Chimie 16 (2013) 257–270
263
Fig. 1. (a) Time dependence of the reaction yield of N-methyl imines of 4-metoxy- and 4-nitrobenzaldehyde; (b) Stacked 1H NMR spectra of the reaction
mixtures after 0, 0.5, 3 and 48 h of contact of 4-nitrobenzaldehyde, CH3NH2ÁHCl and NaHCO3 in the ratio 1:5:5.
A satisfying yield of N-methyl imine of 4-methoxy-
benzaldehyde (65%) was obtained when employing the
reactants’ ratio (aldehyde/CH3NH2ÁHCl/NaHCO3) 1:5:5,
already after 3 h, after grinding (entry 30, Table 2). In
order to reach a comparable yield of N-(3,4-dimethox-
ybenzylidene)methanamine, the reaction mixture was
required to stand overnight (entry 36, Table 2), whereas
the conversion of 3,4,5-trimethoxybenzaldehyde to the
corresponding imine, besides the overnight standing,
necessitated also a 10-fold excess of CH3NH2 (entry 39,
Table 2).
is the rate-limiting one, whereas the second step is faster.
As the nucleophilic attack by the amine is reversible, the
feasibility of imine formation largely depends on the
removal of water in the second step [33]. An acid is
required to protonate the aminal intermediate, but too
much acid would protonate all of the amine and prevent it
from acting as a nucleophile. Thus, imine formation is
sensitive to the amount of acid and it is fastest at about
pH 4–6 [58], making NaHCO3, with pKb ca. 7 and a CO2
driving force, almost an ideal choice for the base utilized to
liberate methylamine from its hydrochloride.
These results motivated us to study the kinetics of this
reaction further. We decided to investigate the time
dependence of the formation of the N-methyl imines of
4-metoxy- and 4-nitrobenzaldehyde, by 1H NMR spectros-
copy, utilizing the reactants’ ratio (aldehyde/CH3NH2ÁHCl/
NaHCO3) 1:5:5, by tracking the yield of the reactions left to
stand after grinding from 10 min to 48 h. A plot (a) of the
yields vs time for the two aldehydes and stacked 1H NMR
spectra (b) of the reaction mixtures after 0, 0.5, 3 and 48 h
of contact of 4-nitrobenzaldehyde, CH3NH2ÁHCl and
NaHCO3 in the ratio 1:5:5 are presented in Fig. 1.
The reaction was expectedly slower in the case of the
electron-rich aldehyde. After 1 h, the isolated yield of N-(4-
methoxybenzylidene)methanamine was 51% (entry 29,
Table 2), whereas the same of N-(4-nitrobenzylidene)-
methanamine was 79% (entry 3, Table 2). However, N-(4-
methoxybenzylidene)methanamine could still be obtained
in a good yield but only after leaving the reaction mixture
to stand overnight.
Mechanistically, the formation of an imine must involve
two steps. First, the amine nitrogen acts as a nucleophile
attacking the carbonyl carbon and a tetrahedral interme-
diate is formed. Dehydration of the intermediate gives an
imine [58]. The data given in Table 2 and in Fig. 1 are in
agreement with the fact that electron-withdrawing sub-
stituents promote the addition of CH3NH2 to an aldehyde,
but also that the electron-donating ones favour the
dehydration step. It can be concluded that the first step
Following the procedure described herein, we prepared
31 N-methyl imines out of which eight (2r, 2s, 2 v, 2w, 2x,
2y, 2z, 2ag, Scheme 1) were synthesized for the first time
ever and their structures were elucidated by spectral
means (1H- and 13C-NMR, IR, MS) (Section 4.6). N-methyl
imines, of some of the aldehydes with electron-donating
substituents, were synthesized in the amounts insufficient
for detailed spectral characterization, due to their lower
electrophilicity (2k, 2w, 2x, 2ab, 2ae, Scheme 1).
In order to evaluate the preparative value of the present
methodology, we carried out this reaction on a gram-scale.
Salicylaldehyde (5 g, 41 mmol) or 4-chlorobenzaldehyde
(2 g, 14 mmol), when reacted with methylamine hydro-
chloride and NaHCO3 (5 mol eq), gave the corresponding
imine in 72 and 84% yield, respectively. The initial product
of salicylaldehyde required no further purification accord-
ing to a GC–MS analysis.
Finally, we tried to perform a solvent-free synthesis of
N-methyl imines of aliphatic aldehydes and aromatic and
aliphatic ketones, but in all of these cases, the reactions
failed. As it is well known, primary aliphatic aldehydes, in
general, give polymeric materials with amines, due to the
ease with which the imines initially formed, undergo
subsequent aldol condensations [32]. On the other side, the
reactions of ketones (both aromatic and aliphatic ones)
were unsuccessful because of the lower electrophilicity, in
part from the greater steric hindrance, of carbonyl groups,
in comparison to those of the aldehydes.

264
N.S. Radulovic´ et al. / C. R. Chimie 16 (2013) 257–270
3. Conclusion
GC–MS. The GC–MS analyses (three repetitions for each
sample) were performed on a Hewlett-Packard 6890 N
gas chromatograph equipped with fused silica capillary
column HP-5MS (5% phenylmethylsiloxane, 30
In conclusion, we have established a convenient one-
pot solvent-free synthesis of N-methyl imines from
aromatic aldehydes, using methylamine hydrochloride
as the methylamine source. This method not only provides
good to high yields, but also eliminates the use of
hazardous solvents, more or less expensive catalysts and
the necessity of work/handling with an anhydrous gas in
pressurized containers. Additionally, the advantages of this
method include mild reaction conditions, the simplicity of
the procedure, easy work-up, as well as the fact that this is
an environmentally benign and inexpensive approach.
Methylamine hydrochloride is easy and safe to handle, and
it could be either commercially obtained or prepared by a
very simple procedure from inexpensive formaldehyde
solution and ammonium chloride. This synthesis provides
high yields of imines of aldehydes with electron-with-
drawing substituents in short reaction times, whereas in
the case of aldehydes with electron-releasing substituents,
yields can be enhanced with an excess of methylamine
hydrochloride and base and/or by prolonged reaction
times. All the before mentioned facts make this method the
simplest one for the synthesis of N-methyl imines of
aromatic aldehydes.
m  0.25 mm, film thickness 0.25
mm, Agilent Technolo-
gies, USA) and coupled with a 5975B mass selective
detector from the same company. The injector and
interface were operated at 250 and 290 8C, respectively.
Oven temperature was raised from 70 to 290 8C at a
heating rate of 5 8C/min and then isothermally held for
20 min. As a carrier gas, He at 1.0 mL/min was used. The
samples, 1
mL of the solutions in Et2O (ca. 1 mg in 1 mL of
Et2O), were injected in a pulsed split mode (the flow was
1.5 mL/min for the first 0.5 min and then set to 1.0 mL/
min throughout the remainder of the analysis; split ratio
40:1). Mass selective detector was operated at the
ionization energy of 70 eV, in the 35–650 amu range
and scanning speed of 0.34 s. The percentage composi-
tion was computed from the total ion chromatogram
peak areas without the use of correction factors.
Qualitative analyses of the reaction mixture constituents
were based on the analysis of the fragmentation patterns
from their MS.
4.3. Materials
4. Experimental
All of the commercially obtained reagents (Aldrich,
USA; Merck, Germany; Roth, Germany; Carlo Erba, Italia;
B.D.H laboratory reagents, England) were used as received,
except that the solvents were purified by distillation.
Methylamine hydrochloride, utilized in the syntheses, was
prepared by the procedure reported by Marvel and Jenkins
[59]. Some of the starting aldehydes were commercial,
while the others were synthetized by the previously
described procedures: 2-acetoxybenzaldehyde and 4-
acetoxy-3-methoxybenzaldehyde [60]; 2-hydroxy-5-
nitrobenzaldehyde [61]; 3-nitrobenzaldehyde [62]; 3-
iodovanilin [63]. Alkoxybenzaldehydes (2-methoxy-, 2-
methoxy-5-nitro-, 3,5-dibromo-2-methoxy-, 2-isopro-
poxy-, 2-(hexyloxy)benzaldehyde and 3-iodo-4-methox-
ybenzaldehyde) were prepared from corresponding
hydroxybenzaldehydes and alkyl halides [64]. The struc-
tures of all of the synthesized aldehydes were confirmed by
spectral means (1H- and 13C-NMR, IR, MS), and spectral
data, which were not available in the literature, are listed
below (the literature survey of the CAS database was
accomplished through the use of SciFinder Scholar 2007
[65]).
4.1. General
Preparative medium-pressure liquid chromatography
(MPLC) was performed with a pump module C-601 and a
pump controller C-610 Work-21 pump (Bu¨chi,
Switzerland) and was carried out on pre-packed column
cartridges (40 Â 75 mm, Silica-gel 60, particle size distri-
bution 40–63 mm, Bu¨chi). Silica-gel 60 on Al plates, layer
thickness 0.2 mm (Kieselgel 60 F254, Merck) was used for
thin layer chromatography (TLC). The spots on TLC were
visualized by UV light (254 nm) and by spraying with 50%
(v/v) aqueous H2SO4 followed by heating. The GC-MS
analyses were performed on a Hewlett-Packard 6890 N gas
chromatograph equipped with fused silica capillary
column
HP-5MS
(5%
phenylmethylsiloxane,
30
m  0.25 mm, film thickness 0.25
m
m, Agilent Technolo-
gies, USA) and coupled with a 5975B mass selective
detector from the same company as detailed below. The IR
measurements (ATR-attenuated total reflectance) were
carried out using a Thermo Nicolet model 6700 FTIR
instrument (Waltham, USA). The NMR spectra were
recorded on a Varian Gemini 200 (1H at 200 MHz, 13C at
50 MHz) spectrometer, using CDCl3 as the solvent.
4.4. Spectral data not available in the literature of the
employed aldehydes
Chemical shifts are expressed in
d (ppm) using TMS
(Me4Si) as an internal standard. Microanalysis of carbon,
hydrogen and nitrogen were carried out with a Carlo Erba
1106 microanalyzer; their results agreed favorably with
the calculated values.
4.4.1. 2-methoxy-5-nitrobenzaldehyde (1r)
Colorless oil; FTIR (neat): 3081, 2984, 2948, 2850, 1678
(C5O), 1584, 1521, 1484, 1468, 1427, 1399, 1338, 1279,
1248, 1163, 1140, 1073, 1016, 940, 906, 831, 746,
634 cmÀ1
;
EIMS m/z 181 [M]+ (100.0), 180 [M–H]+
4.2. Gas chromatography–mass spectrometry analyses
(30.7), 166 [M–CH3]+ (11.2), 164 (27.8), 163 (41.4), 150
[M–OCH3]+ (6.4), 149 [M–CH3OH]+ (9.3), 135 [M–NO2]
(18.7), 134 [M–H–NO2] (34.9), 120 [M–CH3–NO2]+ (29.4),
118 (13.8), 106 [M–CHO–NO2]+ (4.9), 103 (19.9), 92 (33.6),
The reaction progress was monitored and the reaction
mixture composition preliminary were determined by

N.S. Radulovic´ et al. / C. R. Chimie 16 (2013) 257–270
265
77 (47.2), 75 (32.4), 74 (17.1), 64 (22.1), 63 (35.4), 51
4.6. Spectral data of the newly synthesized imines
(11.7); Calcd for C8H7NO4: C 53.04, H 3.89, N 7.73, O
35.33%; found: C 53.06, H 3.88, N 7.80, O 35.26%; RI (HP-
5MS) 1714.
4.6.1. N-(2-nitrobenzylidene)methanamine (2a)
Colorless oil; FTIR (neat): 3099, 3073, 3034, 2972, 2953,
2900, 2850, 2763, 1646 (C5N), 1608, 1574, 1514 (C–NO2,
sym.), 1454, 1444, 1394, 1372, 1348 (C–NO2, sym.), 1213,
999, 965, 938, 843, 779, 742, 699, 685 cmÀ1; EIMS m/z 163
[M–H]+ (0.5), 147 (39.2), 135 [M–NCH3]+ (16.5), 121 (17.0),
118 [M–NO2]+ (9.1), 117 [M–H–NO2]+ (100.0), 105 (4.4),
102 (5.5), 90 (17.4), 89 [M–NCH3–NO2]+ (13.7), 77 (30.0),
76 [M–CHNCH3–NO2]+ (16.6), 65 (7.6), 63 (8.7), 51 (11.0),
50 (10.4), 42 [M–C6H4NO2]+ (17.2); 13C NMR (CDCl3,
50 MHz): 48.2, 124.1, 129.3, 130.4, 130.9, 133.2, 148.6,
158.0; 1H NMR (CDCl3, 200 MHz): 3.57 (d, J = 1.6 Hz, 3H,
NCH3), 7.57 (dt, J = 7.6, 1.6 Hz, 1H, H4), 7.66 (dt, J = 7.6,
1.2 Hz, 1H, H5), 7.98 (dd, J = 7.6, 1.2 Hz, 1H, H3), 8.02 (dd,
J = 7.6, 1.6 Hz, 1H, H6), 8.68 (q, J = 1.6 Hz, 1H, N5CH); Calcd
for C8H8N2O2: C 58.53, H 4.91, N 17.06, O 19.49%; found: C
58.45, H 4.86, N 17.14, O 19.55%; RI (HP-5MS) 1377.
1H NMR spectroscopic data are in accordance with [54].
4.4.2. 3,5-dibromo-2-methoxybenzaldehyde (1s)
White amorphous solid; FTIR (neat): 3067, 2878, 1683
(C5O), 1572, 1556, 1457, 1414, 1380, 1243, 1217 (C–O–C,
asym.), 1144, 975, 890, 870, 811, 746, 717, 628 cmÀ1; EIMS
m/z 296 [M81Br2]+ (48.0), 295 [M81Br2–H]+ (53.0), 294
[M81Br79Br]+ (9.6), 293 [M81Br79Br–H]+ (25.3), 292
[M79Br2]+ (2.2), 291 [M79Br2–H]+ (12.9), 281 [M81Br2–
CH3]+ (25.7), 280 [M81Br2–H–CH3]+ (11.5), 279
[M81Br79Br–CH3]+ (66.3), 278 [M81Br79Br–H–CH3]+
(50.1), 277 [M79Br2–CH3]+ (55.0), 276 [M79Br2–H–CH3]+
(71.4), 267 (10.2), 265 (24.4), 264 [M81Br2–CH3OH]+ (11.9),
263 (22.5), 262 [M81Br79Br–CH3OH]+ (19.1), 261 (6.9), 260
[M79Br2–CH3OH]+ (9.4), 252 [M81Br2–CHO–CH3]+ (16.1),
250 [M81Br79Br–CHO–CH3]+ (36.9), 248 [M79Br2–CHO–
CH3]+ (47.4), 236 [M81Br2–CHO–OCH3]+ (10.3), 234
[M81Br79Br–CHO–OCH3]+ (16.5), 232 [M79Br2–CHO–
OCH3]+ (6.4), 225 (20.6), 223 (42.9), 221 (22.2), 172
(33.3), 170 (33.8), 156 (24.5), 155, (28.9), 143 (32.5), 141
(34.3), 77 (41.5), 75 (53.7), 74 (59.7), 63 (55.9), 62 (64.2),
61 (33.0); 13C NMR (CDCl3, 50 MHz): 63.5, 118.2, 119.2,
130.5, 131.5, 141.3, 159.1, 187.5; 1H NMR (CDCl3,
200 MHz): 3.98 (s, 3H, OCH3), 7.89 (d, J = 2.5 Hz, 1H, H6),
7.93 (d, J = 2.5 Hz, 1H, H4), 10.28 (s, 1H, H7); Calcd for
C8H6Br2O2: C 32.69, H 2.06, Br 54.37, O 10.89%; found: C
32.63, H 2.03%; RI (HP-5MS) 1624.
4.6.2. N-(3-nitrobenzylidene)methanamine (2b)
Colorless oil; FTIR (neat): 3084, 2952, 2875, 2768, 1650
(C5N), 1614, 1521 (C–NO2, asym.), 1474, 1455, 1438,
1395, 1371, 1347 (C–NO2, sym.), 1216, 1124, 999, 954, 829,
807, 732, 673 cmÀ1; EIMS m/z 164 [M]+ (73.4), 163 [M–H]+
(100), 147 (13.6), 118 [M–NO2]+ (23.3), 117 [M–H–NO2]+
(56.5), 105 (3.4), 90 (11.1), 89 [M–NCH3–NO2]+ (13.1), 77
(21.6), 76 [M–CHNCH3–NO2]+ (11.5), 65 (3.6), 63 (8.9), 51
(9.1), 50 (9.8), 42 [M–C6H4NO2]+ (56.4); 13C NMR (CDCl3,
50 MHz): 48.1, 122.6, 124.8, 129.5, 133.2, 137.8, 148.5,
159.8; 1H NMR (CDCl3, 200 MHz): 3.58 (d, J = 1.6 Hz, 3H,
NCH3), 7.60 (t, J = 7.8 Hz, 1H, H5), 8.06 (dt, J = 7.8, 1.2 Hz,
1H, H6), 8.26 (ddd, J = 7.8, 2.0, 1.2 Hz, 1H, H4), 8.37 (q,
J = 1.6 Hz, 1H, N = CH), 8.54 (t, J = 2.0 Hz, 1H, H2); Calcd for
C8H8N2O2: C 58.53, H 4.91, N 17.06, O 19.49%; found: C
58.48, H 4.89, N 17.11, O 19.52%; RI (HP-5MS) 1460.
13C NMR and 1H NMR spectroscopic data are in
accordance with [55].
4.4.3. 2-isopropoxybenzaldehyde (1y)
Colorless oil; FTIR (neat): 2978, 2930, 2862, 2361, 1673
(C5O), 1597, 1581, 1479, 1457, 1385, 1283, 1237 (C–O–C,
asym.), 1192, 1160, 1112, 1092, 1041, 949, 865, 825,
752 cmÀ1; 13C NMR (CDCl3, 50 MHz): 21.9 (2 C), 71.0,
113.9, 120.3, 125.6, 128.2, 135.7, 160.5, 190.2; Calcd for
C10H12O2: C 73.15, H 7.37, O 19.49%; found: C 73.09, H 7.40,
O 19.51%; RI (HP-5MS) 1330.
4.5. General procedure for the solvent-free synthesis of N-
methyl imines of aromatic aldehydes
4.6.3. N-(4-nitrobenzylidene)methanamine (2c)
Yellow-brown amorphous solid; FTIR (neat): 2967, 2901,
2834, 2774, 1648 (C5N), 1601, 1511 (C–NO2, asym.), 1440,
1340 (C–NO2, sym.), 1291, 1219, 1192, 1101, 1001, 972, 953,
847, 832, 813, 745, 692, 682 cmÀ1; EIMS m/z 164[M]+ (73.8),
163 [M–H]+ (100), 147 (7.0), 118[M–NO2]+ (9.7), 117[M–H–
NO2]+ (70.9), 105 (6.8), 91 (9.7), 90 (11.9), 89 [M–NCH3–
NO2]+ (12.7), 77 (15.0), 76 [M–CHNCH3–NO2]+ (11.7), 65
(5.9), 63 (10.6), 51 (9.5), 50 (11.3), 42 [M–C6H4NO2]+ (52.8);
13C NMR (CDCl3, 50 MHz): 48.1, 123.5 (2 C), 128.3 (2 C),
141.5, 148.6, 159.9; 1H NMR (CDCl3, 200 MHz): 3.58 (d,
J = 1.6 Hz, 3H, NCH3), 7.87 (m, 2H, ArH (AA’)), 8.23 (m, 2H,
ArH (BB’)), 8.36 (q, J = 1.6 Hz, 1H, N5CH); Calcd for
C8H8N2O2: C 58.53, H 4.91, N 17.06, O 19.49%; found:
58.50, H 4.90, N 17.09, O 19.51%; RI 1455 (HP-5MS).
1H NMR spectroscopic data are in accordance with
[51,66].
The reactants – corresponding aldehyde (entries 1–60,
Tables 1 and 2) (1.5 mmol), CH3NH3Cl (2–10 mol eq,
Tables 1 and 2) and the base (2–10 mol eq, Tables 1 and 2)
(the amount of CH3NH3Cl and NaHCO3 were equimolar) –
were grinded in a mortar with a pestle for 10 min and then
left to stand at room temperature from 1 h to overnight
(Tables 1 and 2). The reaction was monitored by TLC, GC-
MS and 1H NMR. The reaction mixture was taken up with
Et2O and the resultant suspension was filtrated through a
layer of anhydrous MgSO4. The solvent was evaporated in
vacuo to give the crude product. Some of the obtained
azometines were pure enough for spectral characteriza-
tion, while the others were purified by MPLC. The products
were characterized by IR, 1H, and 13C NMR, MS, whenever
they were synthesized in the sufficient amounts. The
spectral data of the known compound were compared
with those from the literature and showed favorable
agreement.
4.6.4. 3-((methylimino)methyl)benzonitrile (2d)
Colorless oil; FTIR (neat): 3062, 2943, 2854, 2771, 2222
(CBN); 1651 (C = N), 1475, 1455, 1434, 1400, 1360, 1289,

266
N.S. Radulovic´ et al. / C. R. Chimie 16 (2013) 257–270
1147, 1000, 955, 797, 738, 683 cmÀ1; EIMS m/z 144 [M]+
(48.0), 143 [M–H]+ (100.0), 128 [M–CH3–H]+ (1.5), 116
(13.9), 103 (5.1), 102 [M–CHNCH3]+ (12.9), 89 [M–NCH3–
CN]+ (5.5), 76 [M–CHNCH3–CN]+ (6.6), 75 (7.2), 63 (4.0), 51
(4.4), 50 (4.6), 42 [M–C7H4N]+ (30.0); 13C NMR (CDCl3,
50 MHz): 48.0, 112.8, 118.2, 129.4, 131.2, 131.7, 133.4,
137.1, 159.8; 1H NMR (CDCl3, 200 MHz): 3.55 (d, J = 1.6 Hz,
3H, NCH3), 7.53 (t, J = 7.7 Hz, 1H, H5), 7.69 (dt, J = 7.7,
1.5 Hz, 1H, ArH), 7.94 (dt, J = 7.7, 1.5 Hz, 1H, ArH), 8.00 (t,
1.5, 1H, H2), 8.29 (q, J = 1.6 Hz, 1H, N = CH); Calcd for
C9H8N2: C 74.98, H 5.59, N 19.43%; found: C 74.95, H 5.60,
N 19.44%; RI (HP-5MS) 1345.
1H, H6), 8.72 (q, J = 1.7 Hz, 1H, N = CH); Calcd for C8H8ClN:
C 62.55, H 5.25, Cl 23.08, N 9.12%; found: C 62.58, H 5.26, N
9.13%; RI (HP-5MS) 1198.
NMR spectroscopic data are in accordance with
literature (1H NMR [54,68]; 13C NMR [68]).
4.6.8. N-(3-chlorobenzylidene)methanamine (2h)
Colorless oil; FTIR (neat): 2943, 2892, 2855, 2771, 1652
(C = N), 1594, 1568, 1471, 1453, 1429, 1362, 1281, 1262,
1211, 1194, 1073, 1002, 952, 888, 782, 722, 702,
682 cmÀ1; EIMS m/z 155 [M37Cl]+ (14.2), 154 [M37Cl–
H]+ (35.7), 153 [M35Cl]+ (44.2), 152 [M35Cl–H]+ (100.0),
137 (3.3), 127 (3.9), 125 (12.5), 118 [M–Cl]+ (15.8), 117
[M–Cl–H]+ (8.1), 113 (4.7), 112 (6.2), 111 (13.8), 102 (4.0),
91 (4.2), 89 [M–NCH3–Cl]+ (9.9), 76 [M–CHNCH3–Cl]+
(4.5), 77 (5.6), 75 (12.7), 63 (6.3), 51 (5.2), 50 (7.1), 42 [M–
C6H4Cl]+ (29.3); 13C NMR (CDCl3, 50 MHz): 48.1, 126.1,
127.7, 129.8, 130.4, 134.8, 138.1, 160.9; 1H NMR (CDCl3,
200 MHz): 3.51 (d, J = 1.6 Hz, 3H, NCH3), 7.32 (dd, J = 7.9,
6.8 Hz, 1H, H5), 7.37 (dt, J = 7.9, 2 Hz, 1H, ArH), 7.54 (ddd,
J = 6.8, 2, 1.8 Hz, 1H, ArH), 7.71 (t, J = 1.8 Hz, 1H, H2), 8.22
(q, J = 1.6 Hz, 1H, N = CH); Calcd for C8H8ClN: C 62.55, H
5.25, Cl 23.08, N 9.12%; found: C 62.56, H 5.26, N 9.07%; RI
(HP-5MS) 1219.
4.6.5. 4-((methylimino)methyl)benzonitrile (2e)
White amorphous solid; FTIR (neat): 2951, 2882, 2860,
2775, 2223 (CBN), 1649 (C = N), 1606, 1495, 1454, 1394,
1363, 1301, 1290, 1220, 1195, 1161, 1108, 1002, 944, 863,
835, 643 cmÀ1; EIMS m/z 144 [M]+ (51.6), 143 [M–H]+
(100.0), 128 [M–CH3–H]+ (1.8), 116 (13.2), 103 (6.4), 102
[M–CHNCH3]+ (13.2), 89 [M–NCH3–CN]+ (5.0), 76 [M–
CHNCH3–CN]+ (6.2), 75 (6.4), 63 (3.7), 51 (4.2), 50 (4.5), 42
[M–C7H4N]+ (24.1); 13C NMR (CDCl3, 50 MHz): 47.8, 113.2,
118.0, 127.8 (2 C), 131.9 (2 C), 139.6, 160.1; 1H NMR
(CDCl3, 200 MHz): 3.55 (d, J = 1.6 Hz, 3H, NCH3), 7.67 (m,
2H, ArH (AA’)), 7.80 (m, 2H, ArH (BB’)), 8.30 (q, J = 1.6 Hz,
1H, N = CH); Calcd for C9H8N2: C 74.98, H 5.59, N 19.43%;
found: C 75.02, H 5.57, N 19.46%; RI (HP-5MS) 1349.
1H NMR spectroscopic data are in accordance with [67].
1H NMR spectroscopic data are in accordance with [54].
4.6.9. N-(4-chlorobenzylidene)methanamine (2i)
Colorless oil; FTIR (neat): 2944, 2892, 2846, 2769, 1649
(C = N), 1596, 1572, 1488, 1455, 1399, 1296, 1206, 1087,
1013, 1001, 959, 858, 817, 702 cmÀ1; EIMS m/z 155
[M37Cl]+ (17.4), 154 [M37Cl–H]+ (36.6), 153 [M35Cl]+ (52.9),
152 [M35Cl–H]+ (100.0), 137 (4.6), 127 (4.5), 125 (14.2),
4.6.6. N,N’-(1,3-phenylenedimethylidyne)bis(methanamine)
(2f)
Light yellow amorphous solid; FTIR (neat): 2939, 2880,
2847, 2772, 1647 (C = N), 1583, 1455, 1433, 1399, 1355,
+
118 [M–Cl] (5.7), 117 [M–Cl–H]+ (5.5), 113 (4.7), 112
1292, 1267, 1157, 1000, 957, 795, 690, 653, 639 cmÀ1
;
(6.3), 111 (12.9), 102 (5.1), 89 [M–NCH3–Cl]+ (9.7), 77 (4.9),
76 [M–CHNCH3–Cl]+ (3.9), 75 (11.4), 63 (5.7), 51 (4.6), 50
(6.5), 42 [M–C6H4Cl]+ (18.0); 13C NMR (CDCl3, 50 MHz):
48.1, 128.8 (2 C), 129.0 (2 C), 134.7, 136.4, 161.0; 1H NMR
(CDCl3, 200 MHz): 3.51 (d, J = 1.6 Hz, 3H, NCH3), 7.38 (m,
2H, ArH (AA’)); 7.64 (m, 2H, ArH (BB’)), 8.24 (q, J = 1.6 Hz,
1H, N = CH); Calcd for C8H8ClN: C 62.55, H 5.25, Cl 23.08, N
9.12%; found: C 62.47, H 5.25, N 9.15%; RI (HP-5MS) 1219.
1H NMR spectroscopic data are in accordance with
[51,54].
EIMS m/z 160 [M]+ (84.1), 159 [M–H]+ (100.0), 145 [M–
CH3]+ (8.1), 144 [M–CH3–H]+ (3.7), 143 (13.6), 133 (6.4),
132 (7.2), 131 [M–NCH3]+ (4.9), 119.1 (8.0), 118 [M–
CHNCH3]+ (44.1), 117 (20.8), 116 (7.4), 91 (9.1), 90 (6.2), 89
[M–CHNCH3–NCH3]+ (11.0), 77 (9.9), 76 [M–CHNCH3–
CHNCH3]+ (5.0), 65 (3.2), 63 (6.6), 51 (5.4), 42 [M–
C6H4CHNCH3]+ (32.1); 13C NMR (CDCl3, 50 MHz): 48.1
(2 C), 127.8, 128.8, 129.4 (2 C), 136.5 (2 C), 161.8 (2 C); 1
H
NMR (CDCl3, 200 MHz): 3.52 (d, J = 1.6 Hz, 6H, NCH3), 7.44
(t, J = 7.6 Hz, 1H, H5), 7.78 (dd, J = 7.6, 1.6 Hz, 2H, H4,6), 7.97
(bs, 1H, H2), 8.29 (q, J = 1.6 Hz, 2H, N = CH); Calcd for
4.6.10. N-(4-bromobenzylidene)methanamine (2j)
C
10H12N2: C 74.97, H 7.55, N 17.48%; found: C 75.01, H
Light yellow amorphous solid; FTIR (neat): 2943, 2880,
2845, 2768, 1649 (C = N), 1588, 1570, 1487, 1452, 1433,
1400, 1365, 1295, 1066, 1009, 1001, 958, 935, 854, 814,
705, 679 cmÀ1; EIMS m/z 199 [M81Br]+ (52.6), 198 [M81Br–
H]+ (100.0), 197 [M79Br]+ (55.1), 196 [M79Br–H]+ (99.5),
171 (9.7), 169 (10.2), 157 [M81Br–CHNCH3]+ (10.3), 155
[M79Br–CHNCH3]+ (10.3), 118 [M–Br]+ (14.9), 117 [M–Br–
H]+ (14.8), 102 (8.8), 91 (7.3), 90 (8.8), 89 [M–NCH3–Br]+
(12.6), 77 (11.1), 76 [M–CHNCH3–Br]+ (11.9), 75 (12.0), 63
(8.0), 62 (5.0), 59 (5.6), 51 (6.9), 50 (12.4), 42 [M–C6H4Br]+
(25.9); 13C NMR (CDCl3, 50 MHz): 48.1, 124.8, 129.3 (2 C),
131.8 (2 C), 135.1, 161.2; 1H NMR (CDCl3, 200 MHz): 3.50
(d, J = 1.6 Hz, 3H, NCH3), 7.50-7.60 (m, 4H, ArH), 8.22 (q,
J = 1.6 Hz, 1H, N = CH); Calcd for C8H8BrN: C 48.51, H 4.07,
Br 40.34, N 7.07%; found: C 48.47, H 4.05, N 7.10%; RI (HP-
5MS) 1316.
7.56, N 17.45%; RI 1425 (HP-5MS).
4.6.7. N-(2-chlorobenzylidene)methanamine (2g)
Colorless oil; FTIR (neat): 2942, 2891, 2772, 1642
(C = N), 1592, 1571, 1468, 1433, 1399, 1365, 1270, 1201,
1156, 1121, 1050, 1029, 1001, 957, 854, 827, 751, 709,
628 cmÀ1; EIMS m/z 155 [M37Cl]+ (18.9), 154 [M37Cl–H]+
(37.1), 153 [M35Cl]+ (57.7), 152 [M35Cl–H]+ (100.0), 137
(3.5), 125 (12.7), 118 [M–Cl]+ (4.6), 117 [M–Cl–H]+ (4.5),
113 (3.4), 112 (10.2), 111 (8.6), 102 (7.2), 89 [M–NCH3–Cl]+
(10.1), 77 (6.1), 76 [M–CHNCH3–Cl]+ (4.7), 75 (11.1), 63
(6.0), 51 (5.3), 50 (6.6), 42 [M–C6H4Cl]+ (22.1); 13C NMR
(CDCl3, 50 MHz): 48.4, 127.0, 128.1, 129.7, 131.3, 133.2,
134.9, 159.2; 1H NMR (CDCl3, 200 MHz): 3.56 (d, J = 1.7 Hz,
3H, NCH3), 7.25-7.40 (m, 3H, ArH), 7.98 (dd, J = 7.3, 2.5 Hz,

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267
IR and 1H NMR spectroscopic data are in accordance
with [66].
(CDCl3, 50 MHz): 48.3 (C8), 55.3 (OCH3), 110.8 (C3), 120.6
(C5), 124.5 (C1), 126.9 (C6), 131.5 (C4), 158.3 (C7), 158.4
(C2); 1H NMR (CDCl3, 200 MHz): 3.50 (d, J = 1.6 Hz, 3H,
NCH3), 3.83 (s, 3H, OCH3), 6.88 (d, J = 8.4 Hz, 1H, H3), 6.95
(t, J = 7.6 Hz, 1H, H5), 7.35 (ddd, J = 8.4, 7.6, 1.8 Hz, 1H, H4),
7.89 (dd, J = 7.6, 1.8 Hz, 1H, H6), 8.70 (q, J = 1.6 Hz, 1H,
N = CH); Calcd for C9H11NO: C 72.46, H 7.43, N 9.39, O
10.72%; found: C 72.39, H 7.46, N 9.48, O 10.67%; RI (HP-
5MS) 1298.
4.6.11. N-(2-methylbenzylidene)methanamine (2l)
Colorless oil; FTIR (neat): 2934, 2877, 2839, 2771, 1644
(C = N), 1601, 1483, 1454, 1400, 1368, 1286, 1001, 960,
753, 716 cmÀ1; EIMS m/z 133 [M]+ (38.5), 132 [M–H]+
(51.2), 118 [M–CH3]+ (100.0), 117 [M–CH3–H]+ (33.0), 105
(4.9), 104 [M–NCH3]+ (3.4), 103 [M–NH2CH2]+ (5.3), 91 [M–
CHNCH3]+ (26.2), 90 (6.3), 89 [M–NCH3–CH3]+ (9.8), 77
1H NMR spectroscopic data are in accordance with [54].
(7.0), 65 (11.7), 63 (7.3), 51 (6.1), 42 [M–C7H7]+ (10.3); 13
C
NMR (CDCl3, 50 MHz): 19.2, 48.7, 126.2, 127.1, 130.0,
130.7, 134.2, 137.7, 161.0; 1H NMR (CDCl3, 200 MHz): 2.50
(s, 3H, CH3), 3.53 (d, J = 1.6 Hz, 3H, NCH3), 7.14-7.30 (m, 3H,
ArH), 7.83 (dd, J = 7.2, 1.8 Hz, 1H, H6), 8.59 (q, J = 1.6 Hz, 1H,
N = CH); Calcd for C9H11N: C 81.16, H 8.32, N 10.52%;
found: C 81.12, H 8.30, N 10.57%; RI (HP-5MS) 1153.
1H NMR spectroscopic data are in accordance with [54].
4.6.15. N-(3-methoxybenzylidene)methanamine (2p)
Colorless oil; FTIR (neat): 3005, 2943, 2836, 2769, 1650
(C = N), 1582, 1486, 1454, 1432, 1400, 1367, 1317, 1262,
1194, 1167, 1154, 1122, 1038, 1000, 952, 868, 781, 756,
688 cmÀ1; EIMS m/z 149 [M]+ (51.4), 148 [M–H]+ (100.0),
134 [M–CH3]+ (5.7), 133 [M–H–CH3]+ (15.2), 119 [M–
NH2CH2]+ (7.8), 118 [M–OCH3]+ (17.1), 117 [M–CH3OH]+
(4.6), 106 (6.3), 105 (8.3), 91 (5.2), 78 (8.2), 77 (11.3), 65
(5.5), 63 (6.3), 51 (5.6), 42 [M–C6H4OCH3]+ (13.8); 13C NMR
(CDCl3, 50 MHz): 48.0, 55.2, 111.1, 117.3, 121.2, 129.4,
137.6, 159.8, 162.3; 1H NMR (CDCl3, 200 MHz): 3.50 (d,
J = 1.6 Hz, 3H, NCH3), 3.82 (s, 3H, OCH3), 6.96 (ddd, J = 8.0,
2.6, 1.3 Hz, 1H, ArH), 7.18-7.34 (m, 3H, ArH), 8.23 (q,
J = 1.6 Hz, 1H, N = CH); Calcd for C9H11NO: C 72.46, H 7.43,
N 9.39, O 10.72%; found: C 72.42, H 7.44, N 9.43, 10.71%; RI
(HP-5MS) 1291.
4.6.12. N-(3-methylbenzylidene)methanamine (2m)
Colorless oil; FTIR (neat): 2945, 2842, 2763, 1650
(C = N), 1603, 1586, 1480, 1455, 1400, 1362, 1282, 1249,
1158, 999, 955, 781, 692 cmÀ1; EIMS m/z 133 [M]+ (46.2),
132 [M–H]+ (100.0), 118 [M–CH3]+ (21.3), 117 [M–CH3–H]+
(7.5), 116 (5.0), 105 (10.1), 103 [M–NH2CH2] (3.2), 92 (5.3),
91 [M–CHNCH3]+ (26.6), 90 (3.5), 89 [M–NCH3–CH3]+ (6.4),
77 (5.2), 65 (9.4), 63 (5.5), 51 (4.3), 42 [M–C7H7]+ (11.3);
13C NMR (CDCl3, 50 MHz): 21.2, 48.1, 125.4, 128.1, 128.4,
131.3, 135.2, 138.3, 162.6; 1H NMR (CDCl3, 200 MHz): 2.38
(s, 3H, CH3), 3.51 (d, J = 1.6 Hz, 3H, NCH3), 7.24 (bd,
J = 7.6 Hz, 1H, H4), 7.30 (t, J = 7.6 Hz, 1H, H5), 7.46 (bd,
J = 7.6 Hz, 1H, H6), 7.56 (bs, 1H, H2), 8.25 (q, J = 1.6 Hz, 1H,
N = CH); Calcd for C9H11N: C 81.16, H 8.32, N 10.52%;
found: C 81.15, H 8.34, N 10.54%; RI (HP-5MS) 1150.
1H NMR spectroscopic data are in accordance with [54].
4.6.16. N-(4-methoxybenzylidene)methanamine (2q)
Colorless oil; FTIR (neat): 2937, 2884, 2837, 2770, 1650
(C5N), 1604, 1578, 1509, 1457, 1307, 1245 (C–O–C, asym.),
1163, 1007, 1027 (C–O–C, sym.), 961, 829, 775 cmÀ1; EIMS
m/z 149 [M]+ (62.7), 148 [M–H]+ (100.0), 134 [M–CH3]+
(4.2), 133 [M–H–CH3]+ (18.4), 121 (10.5), 118 [M–OCH3]+
(2.4), 117 [M–CH3OH]+ (2.6), 105 (6.8), 91 (5.4), 77 (9.4), 65
(5.6), 51 (5.2), 42 [M–C6H4OCH3]+ (6.7); 13C NMR (CDCl3,
50 MHz): 47.5, 54.8, 113.5 (2 C), 128.9, 129.0 (2 C), 161.1,
161.4; 1H NMR (CDCl3, 200 MHz): 3.48 (d, J = 1.6 Hz, 3H,
NCH3), 3.83 (s, 3H, OCH3), 6.92 (m, 2H, H3,5 (AA’)), 7.65 (m,
2H, H2,6 (MM’)), 8.21 (q, J = 1.6 Hz, 1H, N5CH); Calcd for
C9H11NO: C 72.46, H 7.43, N 9.39, O 10.72%; found: C 72.48,
H 7.39, N 9.44, 10.69%; RI (HP-5MS) 1321.
4.6.13. N-(4-methylbenzylidene)methanamine (2n)
Colorless oil; FTIR (neat): 2942, 2883, 2839, 2774, 1650
(C = N), 1607, 1510, 1451, 1400, 1306, 1172, 1004, 961,
810, 758 cmÀ1; EIMS m/z 133 [M]+ (53.2), 132 [M–H]+
(100.0), 118 [M–CH3]+ (10.8), 117 [M–CH3–H]+ (6.1), 116
(6.1), 105 (10.8), 103 [M–NH2CH2]+ (5.5), 92 (4.9), 91 [M–
CHNCH3]+ (26.0), 89 [M–NCH3–CH3]+ (6.2), 77 (5.3), 65
(9.3), 63 (5.2), 51 (4.6), 42 [M–C7H7]+ (10.3); 13C NMR
(CDCl3, 50 MHz): 21.4, 48.1, 127.8 (2 C), 129.3 (2 C), 133.7,
140.7, 162.4; 1H NMR (CDCl3, 200 MHz): 2.37 (s, 3H, CH3),
3.50 (d, J = 1.6 Hz, 3H, NCH3), 7.21 (m, 2H, H3,5 (AA’)), 7.59
(m, 2H, H2,6 (BB’)), 8.24 (q, J = 1.6 Hz, 1H, N = CH); Calcd for
C9H11N: C 81.16, H 8.32, N 10.52%; found: C 81.18, H 8.30,
N 10.49%; RI (HP-5MS) 1155.
NMR spectroscopic data are in accordance with
literature (1H NMR [51,54] and 13C NMR [69]).
4.6.17. N-(2-methoxy-5-nitrobenzylidene)methanamine (2r)
Colorless oil; FTIR (neat): 3088, 3010, 2951, 2905, 2843,
2772, 1643 (C5N), 1610, 1584, 1509 (C–NO2, asym.), 1480,
1455, 1425, 1340 (C–NO2, sym.), 1263 (C–O–C, asym.),
1184, 1139, 1075 (C–O–C, sym.), 1013, 953, 822, 747,
634 cmÀ1; EIMS m/z 194 [M]+ (9.5), 193 [M–H]+ (68.3), 179
[M–CH3]+ (21.1), 165 [M–NCH3]+ (24.9), 164 [M–NH2CH2]+
(100.0), 163 [M–OCH3]+ (39.9), 148 [M–NO2]+ (9.7), 147
[M–H–NO2]+ (47.4), 133 [M–NH2CH2–OCH3]+ (23.5), 118
[M–NH2CH2–NO2]+ (42.7), 107 (3.0), 105 (9.4), 104 (11.6),
90 (6.9), 89 (7.5), 77 (13.5), 76 (10.6), 65 (3.9), 63 (13.1), 51
(7.4), 42 [M–C6H3OCH3NO2]+ (33.5); 13C NMR (CDCl3,
50 MHz): 48.4, 56.3, 110.9, 123.2, 125.5, 126.9, 141.8,
156.1, 162.6; 1H NMR (CDCl3, 200 MHz): 3.56 (d, J = 1.6 Hz,
3H, NCH3), 4.00 (s, 3H, OCH3), 7.00 (d, J = 9.2 Hz, 1H, H3),
1H NMR and IR spectroscopic data are in accordance
with literature (1H NMR [51,66]; IR [66]).
4.6.14. N-(2-methoxybenzylidene)methanamine (2o)
Colorless oil; FTIR (neat): 3002, 2938, 2883, 2837, 2770,
1642 (C = N), 1598, 1581, 1487, 1464, 1437, 1367, 1285,
1245 (C–O–C, asym.), 1160, 1109, 1025 (C–O–C, sym.), 999,
958, 857, 785, 752, 634 cmÀ1; EIMS m/z 149 [M]+ (10.1),
148 [M–H]+ (49.0), 134 [M–CH3]+ (26.9), 133 [M–H–CH3]+
(22.6), 120 [M–NCH3]+ (29.5), 119 [M–H2NCH2]+ (100.0),
118 [M–OCH3]+ (75.2), 105 (15.0), 91 (49.2), 77 (21.3), 65
(10.3), 51 (13.3), 42 [M–C6H4OCH3]+ (21.4); 13C NMR

268
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8.26 (dd, J = 9.2, 2.9 Hz, 1H, H4), 8.65 (q, J = 1.6 Hz, 1H,
N5CH), 8.78 (d, J = 2.9 Hz, 1H, H6); Calcd for C9H10N2O3: C
55.67, H 5.19, N 14.43, O 24.72%; found: C 55.62, H 5.17, N
14.47, O 24.74%; RI (HP-5MS) 1793.
50 MHz): 47.9, 56.0 (2 C), 60.8, 104.7 (2 C), 131.7, 140.0,
153.3 (2 C), 161.9; 1H NMR (CDCl3, 200 MHz): 3.51 (d,
J = 1.5 Hz, 3H, NCH3), 3.89 (s, 3H, C4–OCH3), 3.91 (s, 6H, C3–
OCH3, C5–OCH3), 6.96 (s, 2H, H2,6), 8.18 (q, J = 1.5 Hz, 1H,
N5CH); Calcd for C11H15NO3: C 63.14, H 7.23, N 6.69, O
22.94%; found: C 63.17, H 7.22, N 6.74, O 22.87%; RI (HP-
5MS) 1671.
4.6.18. N-(3,5-dibromo-2-nitrobenzylidene)methanamine
(2s)
White amorphous solid; FTIR (neat): 3065, 2943, 2877,
2828, 2761, 1649 (C5N), 1572, 1553, 1454, 1410, 1377,
1353, 1219 (C–O–C, asym.), 1146, 1006, 988, 948, 864, 812,
708, 651 cmÀ1; EIMS m/z 309 [M81Br2]+ (2.0), 308 [M81Br2–
H]+ (14.2), 307 [M81Br79Br]+ (4.8), 306 [M81Br79Br–H]+
(25.7), 305 [M79Br2]+ (2.2), 304 [M79Br2–H]+ (12.9), 294
[M81Br2–CH3]+ (11.4), 293 [M81Br2–H–CH3]+ (7.3), 292
[M81Br79Br–CH3]+ (23.8), 291 [M81Br79Br–H–CH3]+ (13.6),
290 [M79Br2–CH3]+ (14.3), 289 [M79Br2–H–CH3]+ (8.8), 279
[M81Br2–NH2CH2]+ (52.1), 278 [M81Br2–OCH3]+ (54.3), 277
[M81Br79Br–NH2CH2]+ (100.0), 276 [M81Br79Br–OCH3]+
(84.5), 275 [M79Br2–NH2CH2]+ (50.4), 274 [M79Br2–
OCH3]+ (39.6), 267 [M81Br2–CHNCH3]+ (2.1), 265
[M81Br79Br–CHNCH3]+ (5.6), 263 [M79Br2–CHNCH3]+
(4.6), 198 (33.5), 196 (40.5), 118 (11.6), 117 (17.5), 75
(25.4), 74 (23.4), 63 (16.3), 62 (17.3), 42 [M–
C6H2OCH3Br2]+ (75.5); 13C NMR (CDCl3, 50 MHz): 48.5,
62.4, 117.9, 118.4, 129.5, 132.3, 137.2, 155.8, 156.2; 1H
NMR (CDCl3, 200 MHz): 3.57 (d, J = 1.6 Hz, 3H, NCH3), 3.85
(s, 3H, OCH3), 7.73 (d, J = 2.4 Hz, 1H, H6), 8.02 (d, J = 2.4 Hz,
1H, H4), 8.50 (q, J = 1.6 Hz, 1H, N5CH); Calcd for
C9H9Br2NO: C 35.21, H 2.96, N 4.56, O 5.21%; found: C
35.24, H 3.00, N 4.52%; RI (HP-5MS) 1722.
IR and 1H NMR spectroscopic data are in accordance
with [53].
4.6.21. N-(3-iodo-4,5-dimethoxybenzylidene)methanamine
(2v)
Colorless oil; FTIR (neat): 3087, 2990, 2968, 2926, 2850,
1646 (C5N), 1586, 1560, 1461, 1403, 1364, 1267 (C–O–C,
asym.), 1228, 1136, 1164, 1042 (C–O–C, sym.), 1004, 946,
835, 798, 747, 641 cmÀ1; EIMS m/z 305 [M]+ (100.0), 304
[M–H]+ (39.0), 290 [M–CH3]+ (17.4), 274 [M–OCH3]+ (10.9),
259 [M–CH3–OCH3]+ (4.2), 246 [M–NCH3–CH3–CH3]+ (4.8),
178 [M–I]+ (4.0), 163 [M–I–CH3]+ (7.6), 162 [M–H–I–CH3]+
(8.4), 148 [M–I–NH2CH2]+ (11.5), 132 [M–I–CH3–OCH3]+
(12.9), 118 [M–I–NCH3–OCH3]+ (12.2), 90 (4.5), 89 (10.4),
77 (9.9), 65 (6.0), 63 (7.7), 51 (4.7), 50 (5.7), 42 [M–
C6H2(OCH3)2I]+ (18.0); 13C NMR (CDCl3, 50 MHz): 48.0,
56.0, 60.5, 92.0, 110.2, 131.5, 134.7, 150.9, 152.8, 160.3; 1H
NMR (CDCl3, 200 MHz): 3.51 (d, J = 1.6 Hz, 3H, NCH3), 3.86
(s, 3H, C5–OCH3)*, 3.90 (s, 3H, C4–OCH3) *, 7.36 (d,
J = 1.8 Hz, 1H, H2), 7.57 (d, J = 1.8 Hz, 1H, H6), 8.13 (q,
J = 1.6 Hz, 1H, N5CH); Calcd for C10H12INO2: C 39.36, H
3.96, N 4.59, O 10.49%; found: C 39.42, H 3.94, N 4.56%; RI
(HP-5MS) 1832.
*Interchangeable protons.
4.6.19. N-(4,5-dimethoxybenzylidene)methanamine (2t)
Colorless amorphous solid; FTIR (neat): 3002, 2936,
2837, 2771, 1646 (C5N), 1585, 1509, 1452, 1418, 1263 (C–
O–C, asym.), 1235, 1134, 1021 (C–O–C, sym.), 956, 867,
807, 749, 731 cmÀ1; EIMS m/z 179 [M]+ (100.0), 178 [M–
H]+ (98.5), 164 [M–CH3]+ (24.4), 163 [M–H–CH3]+ (10.4),
148 [M–OCH3]+ (38.9), 133 [M–OCH3–CH3]+ (13.5), 120
[M–NCH3–CH3–CH3]+ (13.1), 119 [M–OCH3–NCH3]+ (9.1),
105 (5.1), 104 (5.7), 95 (9.7), 92 (7.6), 91 (4.7), 77 (13.9), 65
(8.6), 51 (8.1), 42 [M–C6H3(OCH3)2]+ (14.7); 13C NMR
(CDCl3, 50 MHz): 47.8, 55.7 (2 C), 108.1, 110.2, 122.7,
129.3, 149.1, 151.0, 161.9; 1H NMR (CDCl3, 200 MHz): 3.49
(d, J = 1.4 Hz, 3H, NCH3), 3.91 (s, 3H, C3–OCH3)*, 3.93 (s, 3H,
C3–OCH3)*, 6.87 (d, J = 8.2 Hz, 1H, H5), 7.12 (dd, J = 8.2,
1.9 Hz, 1H, H6), 7.41 (d, J = 1.9 Hz, 1H, H2), 8.19 (q,
J = 1.4 Hz, 1H, N5ÀCH); Calcd for C10H13NO2: C 67.02, H
7.31, N 7.82, O 17.85%; found: C 66.95, H 7.32, N 7.80, O
17.93%; RI (HP-5MS) 1533.
4.6.22. N-(2-isopropoxybenzylidene)methanamine (2y)
Colorless oil; FTIR (neat): 2976, 2935, 2885, 2771, 1641
(C5N), 1598, 1579, 1482, 1452, 1371, 1284, 1239 (C–O–C,
asym.), 1159, 1114, 1000, 1043, 951, 867, 752 cmÀ1; EIMS
m/z 177 [M]+ (2.9), 176 [M–H]+ (5.5), 162 [M–CH3]+ (43.6),
147 [M–NH2CH2]+ (16.1), 135 [M–C3H6]+ (14.3), 134 [M–
C3H7]+ (100.0), 119 [M–C3H7–CH3]+ (27.0), 118 [M–
OC3H7]+ (67.0), 107 (18.8), 91 (10.4), 77 (12.6), 65 (8.3),
51 (6.5), 42 [M–C6H4OCH3]+ (12.3); 13C NMR (CDCl3,
50 MHz): 22.1 (2 C), 48.5, 70.9, 113.9, 120.7, 125.8, 127.1,
131.5, 157.1, 158.8; 1H NMR (CDCl3, 200 MHz): 1.37 (d,
J = 6.1 Hz, 6H, OCH(CH3)2), 3.52 (d, J = 1.6 Hz, 3H, NCH3),
4.60 (sep, J = 6.1 Hz, 1H, OCH(CH3)2), 6.87–7.05 (m, 2H,
ArH), 7.34 (ddd, J = 8.2, 7.5, 1.8 Hz, 1H, H4), 7.90 (dd, J = 7.6,
1.8 Hz, 1H, H6), 8.71 (q, J = 1.6 Hz, 1H, N5CH); Calcd for
C
11H15NO: C 74.54, H 8.53, N 7.90, O 9.03 %; found: C 74.60,
H 8.52, N 7.86, O 9.02 %; RI (HP-5MS) 1371.
*Interchangeable protons.
4.6.23. N-(2-(hexyloxy)benzylidene)methanamine (2z)
Colorless oil; FTIR (neat): 2930, 2857, 2770, 1642
(C5N), 1599, 1581, 1487, 1454, 1365, 1296, 1286, 1243 (C–
O–C, asym.), 1159, 1044, 1000, 958, 752 cmÀ1; EIMS m/z
219 [M]+ (2.2), 218 [M–H]+ (3.9), 204 [M–CH3]+ (6.1), 190
4.6.20. N-(3,4,5-dimethoxybenzylidene)methanamine (2u)
Colorless amorphous solid; FTIR (neat): 2939, 2839,
1649 (C5N), 1583, 1500, 1455, 1416, 1369, 1325, 1229 (C–
O–C, asym.), 1121, 1001, 831, 713, 624 cmÀ1; EIMS m/z 209
[M]+ (100.0), 208 [M–H]+ (53.8), 194 [M–CH3]+ (29.0), 178
[M–OCH3]+ (24.3), 164 [M–NH2CH2–CH3]+ (8.2), 163 [M–
OCH3–CH3]+ (8.0), 162 [M–CH3OH–CH3]+ (8.1), 151 (13.5),
136 [M–CHNCH3–OCH3]+ (11.4), 125 (17.2), 110 (10.0),
104 (2.8), 95 (9.1), 79 (6.5), 77 (5.0), 66 (5.9), 65 (5.4), 53
(5.5), 42 [M–C6H2(OCH3)3]+ (13.0); 13C NMR (CDCl3,
[M–C2H5]+ (4.2), 189 [M–NH2CH2]+ (4.7), 176 [M–C3H7]+
+
(3.0), 162 [M–C4H9]+ (9.6), 148 [M–C5H11
]
(100.0), 135
+
+
[M–C6H12
]
(18.5), 134 [M–C6H13
]
(41.7), 120 [M–CH3–
] (24.1), 118 [M–OC6H13] (63.5), 107 (13.8), 91
+
+
C6H12
(12.5), 77 (9.8), 65 (5.9), 51 (3.9), 42 [M–C6H4OCH3]+
(13.8); 13C NMR (CDCl3, 50 MHz): 14.0, 22.5, 25.7, 29.1,

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269
31.5, 68.3, 48.5, 111.9, 120.5, 124.7, 126.8, 131.6, 158.1,
158.4; 1H NMR (CDCl3, 200 MHz): 0.92 (t, J = 6.6 Hz, 3H,
H6’), 1.30–1.42 (m, 4H, H4’,5’), 1.43–1.53 (m, 2H, H3’), 1.82
(qui, J = 6.4 Hz, 2H, H2’), 4.00 (t, J = 6.4 Hz, 2H, H1’), 3.52 (d,
J = 1.6 Hz, 3H, NCH3), 6.91 (d, 8.4 Hz, H3), 6.97 (t, 7.4 Hz,
H5), 7.34 (ddd, J = 8.4, 7.4, 1.8 Hz, 1H, H4), 7.90 (dd, J = 7.7,
1.8 Hz, 1H, H6), 8.73 (q, J = 1.6 Hz, 1H, N5CH); Calcd for
8.15 (dd, J = 8.4, 1.1 Hz, 1H, ArH), 8.66 (dd, J = 8.4, 1.1 Hz,
1H, ArH), 8.85 (q, J = 1.6 Hz, 1H, N5CH), 8.95 (d, J = 4.4 Hz,
3H, H2); Calcd for C11H10N2: C 77.62, H 5.92, N 16.46%;
found: C 77.63, H 5.90, N 16.50%; RI 1622 (HP-5MS).
Acknowledgements
C
14H21NO: C 76.67, H 9.65, N 6.39, O 7.29%; found: C 76.74,
The authors acknowledge support from the Ministry of
Education, Science and Technological development of the
Republic of Serbia (Project 172061).
H 9.70, N 6.37, O 7.19%; RI (HP-5MS) 1736.
4.6.24. 2-((methylimino)methyl)phenol (2aa)
Colorless oil; FTIR (neat): 3054, 3007, 2954, 2887, 2854,
2750 br (O–HÁÁÁN), 1634 (C5N); 1582, 1495, 1450, 1417,
1401, 1368, 1277 (C–O), 1211, 1151, 1036, 1005, 965, 837,
752, 647 cmÀ1; EIMS m/z 135 [M]+ (100.0), 134 [M–H]+
(95.1), 120 [M–CH3]+ (59.2), 118 [M–OH]+ (17.5), 107
(17.6), 91 (8.3), 77 (14.5), 65 (11.8), 51 (10.4), 42 [M–
C6H4OH]+ (14.8); 13C NMR (CDCl3, 50 MHz): 45.9, 116.9,
118.4, 118.8, 130.9, 131.9, 161.1, 166.1; 1H NMR (CDCl3,
200 MHz): 3.47 (d, J = 1.4 Hz, 3H, NCH3), 6.86 (td, J = 7.6,
1.1 Hz, 1H, H5), 6.95 (d, J = 8.2 Hz, 1H, H3), 7.23 (dd, J = 7.6,
1.6 Hz, 1H, H6), 7.29 (ddd, J = 8.2, 7.6, 1.6 Hz, 1H, H4), 8.33
(q, J = 1.4 Hz, 1H, N5CH); Calcd for C8H9NO: C 71.09, H
6.71, N 10.36, O 11.84%; found: C 71.01, H 6.76, N 10.31, O
11.92%; RI (HP-5MS) 1230.
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4.6.25. 2-methoxy-5-((methylimino)methyl)phenol (2ad)
Colorless oil; FTIR (neat): 3400 br (O–H), 2932, 2840,
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