Activation of C-H bonds of hydrocarbons by the ArH-alkali metal systems in THF (ArH - naphthalene, biphenyl, anthracene, phenanthrene, trans-stilbene, pyrene). Alkylation of naphthalene and toluene with ethene

Article abstract of DOI:10.1016/j.jorganchem.2008.12.034

Systems based on naphthalene and alkali metals (Li, Na, K) in THF are able to induce the alkylation of naphthalene with ethene at room temperature and atmospheric pressure. The highest activity in this reaction is exhibited by the naphthalene-potassium system which converts naphthalene into 1-ethylnaphthalene (1) and small amounts of two isomeric dihydro derivatives of 1 in a yield of 85% (24 h, K:C₁₀H₈ = 2:1). The same alkylation products are formed when metallic sodium is used instead of potassium. The interaction of ethene with the naphthalene-lithium system (24 h, Li:C₁₀H₈ = 2:1) affords 1 together with 1-n-butylnaphthalene (4), 1-n-hexylnaphthalene (5), 1-n-oktylnaphthalene (6) and dihydro derivatives of 5 and 6 in a total yield of 60%. Alkylation of toluene with ethene in the naphthalene-alkali metal systems leads to the formation of higher monoalkylbenzenes. The greatest toluene conversion (48%, 24 h) is observed on using the lithium-containing system (Li:C₁₀H₈ = 2:1), in the presence of which a mixture of n-propylbenzene (11), n-pentylbenzene (12), 3-phenylpentane (13) and 3-phenylheptane (14) is produced from ethene and toluene. On the replacement of lithium by sodium or potassium, only 11 and 13 are obtained. A treatment of biphenyl, phenanthrene, trans-stilbene, pyrene and anthracene with alkali metals in THF also gives systems capable of catalyzing the alkylation of toluene with ethene at 22 °C. Of particularly active is the stilbene-lithium system (Li:stilbene = 3:1) which converts toluene into a mixture of 11-14, n-heptylbenzene and 5-phenylnonane in a yield of 58%. In all cases, the rate of the alkylation considerably increases in the presence of the solid phase of alkali metal. The mechanism of the reactions found is discussed.

Full text of DOI:10.1016/j.jorganchem.2008.12.034

Journal of Organometallic Chemistry 694 (2009) 1459–1466
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Journal of Organometallic Chemistry
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Activation of C–H bonds of hydrocarbons by the ArH–alkali metal systems in
THF (ArH – naphthalene, biphenyl, anthracene, phenanthrene, trans-stilbene,
pyrene). Alkylation of naphthalene and toluene with ethene
S. Rummel a, M.A. Ilatovskaya b, S.M. Yunusov b, E.S. Kalyuzhnaya b, V.B. Shur b,
*
a Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, D-04318 Leipzig, Germany
b A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov Street 28, Moscow 119991, Russia
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 10 June 2008
Received in revised form 28 November 2008
Accepted 17 December 2008
Available online 27 December 2008
Systems based on naphthalene and alkali metals (Li, Na, K) in THF are able to induce the alkylation of
naphthalene with ethene at room temperature and atmospheric pressure. The highest activity in this
reaction is exhibited by the naphthalene–potassium system which converts naphthalene into 1-ethyl-
naphthalene (1) and small amounts of two isomeric dihydro derivatives of 1 in a yield of 85% (24 h,
K:C10H8 = 2:1). The same alkylation products are formed when metallic sodium is used instead of potas-
sium. The interaction of ethene with the naphthalene–lithium system (24 h, Li:C10H8 = 2:1) affords 1
together with 1-n-butylnaphthalene (4), 1-n-hexylnaphthalene (5), 1-n-oktylnaphthalene (6) and dihy-
dro derivatives of 5 and 6 in a total yield of 60%. Alkylation of toluene with ethene in the naphtha-
lene–alkali metal systems leads to the formation of higher monoalkylbenzenes. The greatest toluene
conversion (48%, 24 h) is observed on using the lithium-containing system (Li:C10H8 = 2:1), in the pres-
ence of which a mixture of n-propylbenzene (11), n-pentylbenzene (12), 3-phenylpentane (13) and 3-
phenylheptane (14) is produced from ethene and toluene. On the replacement of lithium by sodium or
potassium, only 11 and 13 are obtained. A treatment of biphenyl, phenanthrene, trans-stilbene, pyrene
and anthracene with alkali metals in THF also gives systems capable of catalyzing the alkylation of tol-
uene with ethene at 22 °C. Of particularly active is the stilbene–lithium system (Li:stilbene = 3:1) which
converts toluene into a mixture of 11–14, n-heptylbenzene and 5-phenylnonane in a yield of 58%. In all
cases, the rate of the alkylation considerably increases in the presence of the solid phase of alkali metal.
The mechanism of the reactions found is discussed.
Dedicated to the memory of the late
Professor Manfred Wahren.
Keywords:
Activation of C–H bonds
Alkali metals
Aromatic hydrocarbons
Ethene
Alkylation
Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
ecules takes place at room temperature. An important feature of
this interesting reaction is its strong acceleration when the solid
Radical anion adducts of alkali metals with naphthalene and
other aromatic hydrocarbons (biphenyl, anthracene, trans-stilbene,
etc.) are widely used in chemical research owing to their ability to
efficiently transfer electrons to various organic and inorganic sub-
strates (for reviews, see e.g. [1–3]). They are successfully applied in
organic and organometallic synthesis, catalysis and other fields. Of
particular importance was the discovery of a high catalytic activity
of such adducts in the polymerization of 1,3-dienes and some
monoenes to produce ‘‘living” polymers.
Previously, we have reported on a new intriguing property of
these remarkable reagents [4]. It turned out that on an addition
of metallic sodium to a solution of [D0]naphthalene and [D10]naph-
thalene in [D0]THF a system is formed in which the hydrogen–deu-
terium exchange between naphthalene rings of sodium
naphthalide as well as between sodium naphthalide and THF mol-
phase of the alkali metal is present in the mixture. Under homoge-
neous conditions, i.e. at a Na:C10H8 molar ratio of 1:1, the rate of
the process decreases. A number of other hydrocarbons such as
benzene, toluene, ethene and even methane can also be drawn at
room temperature into a similar H/D exchange reaction with naph-
thalene rings, in the case of toluene both the hydrogen atoms of the
phenyl core and of the methyl group being involved in the process
of the exchange.
Taking into account so high an efficiency of the above naphtha-
lene–sodium system in C–H bond activation, we decided to test sys-
tems of such a type as catalysts for the alkylation of hydrocarbons
with ethene under mild conditions. In 1971, Watanabe and co-
workers described shortly the insertion reaction of isoprene into
the C–H bond of the methyl group of toluene under the action of
naphthalene–sodium in THF at room temperature [5]. The reaction
was conducted at a Na:C10H8 molar ratio of 2:1, i.e. in the presence
of an excess of the alkali metal. Later, Carnahan and Closson ob-
served the formation of small amounts (7%) of 1-ethylnaphthalene
* Corresponding author.
E-mail address: vbshur@ineos.ac.ru (V.B. Shur).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.12.034

1460
S. Rummel et al. / Journal of Organometallic Chemistry 694 (2009) 1459–1466
(1) together with its two dihydro derivatives (45%; after hydrolysis)
in the interaction of ethene for 1 h with a mixture of naphthalene
and excess lithium (Li:C10H8 = 3:1) in tetrahydropyran at 25 °C
[6]. It was also demonstrated by Fochi and Nucci in 1991 [7] that
the naphthalene–potassium system (K:C10H8 ꢀ 1.67:1) in 1,2-
dimethoxyethane (DME) is capable of catalyzing at room tempera-
ture the selective dehydrogenation of 1,4-cyclohexadiene to ben-
zene and molecular hydrogen. Interestingly, when biphenyl and
phenanthrene were used instead of naphthalene in this system
the concurrent disproportionation of 1,4-cyclohexadiene to ben-
zene and cyclohexene occurred along with the dehydrogenation,
and when naphthalene was replaced by anthracene only isomeriza-
tion of 1,4-cyclohexadiene to its 1,3-isomer took place. The naph-
thalene–sodium and anthracene–sodium systems proved to be
inactive towards 1,4-cyclohexadiene. No transformations of 1,4-
cyclohexadiene were also observed on the use of a negatively
charged electrode as a source of electrons in place of the above-
mentioned arene–alkali metal systems.
In the present article, the reactions of the naphthalene and tolu-
ene alkylation with ethene at room temperature in the naphtha-
lene–alkali metal systems in THF are described in detail. The
alkylation of toluene with ethene catalyzed by analogous systems
based on biphenyl, anthracene, trans-stilbene, phenanthrene and
pyrene is also reported. The efficiency of the reactions studied de-
pends substantially on the nature of the starting reagents, their ra-
tio and other factors. In all cases, the greatest naphthalene and
toluene conversions into alkylation products are observed when
an excess of the alkali metal is present in the system. A short preli-
minary account of a part of this work has been published in [8].
As is known, alkali metals (Na, K), their adducts with polycyclic
aromatic hydrocarbons (in the absence of a solvating solvent) as
well as graphite–potassium systems are also able to catalyze the
alkylation of toluene and some other hydrocarbons with olefins,
including ethene [3,9–11]. However, these reactions proceed with
noticeable rates only at elevated temperatures (90–250 °C). Re-
cently, Yus and co-workers reported the reactions of some simple
terminal and strained internal alkenes (propene, isobutene, nor-
bornene, etc.) with systems based on polycyclic arenes (biphenyl,
naphthalene, phenanthrene) and excess lithium metal (Li:
arene = 4:1) in THF at 25 °C [12]. Under these conditions, products
of the carbolithiation of the above alkenes by the arene dianions are
produced after 1–2 h. For other papers concerning addition reac-
tions of organometallic derivatives of alkali metals to alkenes, see
[13–16] and references cited therein.
were carried out at room temperature and atmospheric pressure.
The initial naphthalene concentration was 2 M and a Na:C10H8 mo-
lar ratio was 2:1. On using such a ratio of the reagents, half the ta-
ken amount of metallic sodium was dissolved to give radical anion
of naphthalene while another half remained undissolved, and thus
the reaction with ethene was conducted here in the presence of the
solid phase of the alkali metal.
The results of the experiments showed that under these condi-
tions a gradual absorption of ethene by the naphthalene–sodium
system occurs and 1 appears in the solution. After 24 h, the amount
of absorbed ethene reaches 0.73 mol per mol of naphthalene and
the yield of 1 is 35% based on naphthalene (Table 1). Along with
1, small quantities (ꢀ2%) of its two dihydro derivatives (2 and 3)
are also obtained. Further increase in the reaction time (to 48 h)
does not increase significantly the amount of absorbed ethene
(0.82 mol per mol of naphthalene) and the naphthalene conversion
(38%).
A decrease in a Na:C10H8 molar ratio from 2:1 to 1:1 substan-
tially diminishes both the rate of ethene uptake and the efficiency
of the alkylation (Table 1). Even stronger retarding effect on ethene
absorbtion and the alkylation reaction is caused by the replace-
ment of THF with DME. On carrying out the reaction in the pres-
ence of [15]crown-5 (one mol per mol of naphthalene) only trace
amounts of 1 (and no 2 and 3) are produced after 24 h (0.12 mol
of absorbed ethene per mol of naphthalene). Similar effects of
the nature of an ethereal solvent, a Na:C10H8 ratio and additives
of [15]crown-5 have previously been observed in the reactions of
the hydrogen–deuterium exchange of hydrocarbons in the naph-
thalene–sodium system [4]. When a mixture of naphthalene with
sodium in THF (Na:C10H8 = 2:1) is held for 3 h under stirring in
an argon atmosphere, the activity of the system in the subsequent
reaction with ethene only insignificantly lowers.
Even higher efficiency in the naphthalene alkylation with eth-
ene is exhibited by the naphthalene–potassium system in THF (Ta-
ble 1). On using this system, the conversion of naphthalene into 1
at room temperature reaches 83% after 24 h (K:C10H8 = 2:1). The
reaction products contain also small quantities (2%) of 2 and 3. If
DME is used as a solvent instead of THF the rate of the alkylation
again considerably decreases, even though the amount of absorbed
ethene increases. It should be noted that when 1 is introduced into
the reaction with the naphthalene–potassium system in THF under
Ar (K:C10H8:1 = 2:1:0.17) no 2 and 3 are formed (22 °C, 24 h). This
means that the formation of small amounts of 2 and 3 in the naph-
thalene alkylation with ethene can not be due to the possible pres-
ence of traces of moisture in the system.
In the interaction of ethene with the naphthalene–lithium sys-
tem in THF at 22 °C (24 h, Li:C10H8 = 2:1), 1-n-butylnaphthalene (4)
(yield 15%), 1-n-hexylnaphthalene (5) (9%), 1-n-octylnaphthalene
(6) (5%) as well as two dihydro derivatives (7 and 8) of 5 (3%)
2. Results and discussion
In the first experiments, the interaction of ethene with the
naphthalene–sodium system in THF was studied. The reactions
Table 1
Alkylation of naphthalene with ethene in the naphthalene–alkali metal systems in THF and DME.a
M
M:C10H8 (mol/
mol)
Solvent Reaction time
(h)
Absorbed C2H4
Yield of alkylation products (%)b
C2H4 consumption for
alkylation
Naphthalene
conversion (%)
(mmol) (mol/mol
C10H8)
1
2 + 3
4
5
6
7 + 8 9 + 10 (mmol) (mol/mol
C10H8)
Li
2:1
THF
THF
THF
THF
THF
THF
DME
THF
DME
24
2
4
24
48
24
24
24
24
5.40
0.63
1.08
2.19
2.43
1.38
0.66
2.60
3.60
1.80
0.21
0.36
0.73
0.82
0.46
0.22
0.90
1.20
26
17
31
35
36
16
9
–
–
–
2
2
–
–
2
–
15
–
–
–
–
–
–
–
–
9
–
–
–
–
–
–
–
–
5
–
–
–
–
–
–
–
–
3
–
–
–
–
–
–
–
–
2
–
–
–
–
–
–
–
–
3.60
0.51
0.93
1.11
1.14
0.48
0.27
2.55
1.14
1.20
0.17
0.31
0.37
0.38
0.16
0.09
0.85
0.38
60
17
31
37
38
16
9
Na 2:1
2:1
2:1
2:1
1:1
2:1
2:1
2:1
K
83
38
85
38
a
22 °C, 1 atm, 3 mmol of naphthalene, [C10H8]o = 2 M.
Based on naphthalene.
b

S. Rummel et al. / Journal of Organometallic Chemistry 694 (2009) 1459–1466
1461
and two dihydro derivatives (9 and 10) of 6 (2%) are produced to-
gether with 1 (26%) in an overall yield of 60% (Table 1). Another
distinctive feature of the lithium-containing system is that it ab-
sorbs significantly greater quantities of ethene (1.8 mol per mol
of naphthalene for 24 h) than the corresponding sodium- and
potassium-based systems. Notably, in all of the above naphtha-
lene–lithium and naphthalene–sodium systems, the amount of ab-
sorbed ethene noticeably exceeds its consumption for the
formation of alkylation products (Table 1), which can be explained
by the involvement of ethene in some other reactions, for example,
with the alkali metal (activated by naphthalene) to give aliphatic
organolithium or organosodium compounds. This assumption is
supported by the data of Rautenstrauch [17] who showed that
the interaction of ethene with a mixture of naphthalene and biphe-
nyl in dimethoxymethane in the presence of a large excess of lith-
ium metal (Li:C10H8:Ph2 = 900:1:5.6) at ꢁ10 °C for 20 h affords
vynillithium, 1,4-dilithiobutane, 1,6-dilithiohexane, 3-butenyllithi-
um, n-butyllithium and probably lithium hydride [18]. It has been
assumed that biphenyl plays a role of the active ‘‘carrier” of the al-
kali metal in this system, and two possible reaction mechanisms
have been proposed. One of them suggests the transfer of electrons
and lithium cations to ethene from the radical anion and/or dian-
ion of biphenyl. According to another mechanism, ethene is di-
rectly attacked by some active form of lithium, which appears in
the solution due to the equilibriums (cf. [4]):
yield is produced (Table 3). Here too, a decrease in a Li:C10H8 ratio
from 2:1 to 1:1 or the use of DME instead of THF considerably re-
duces the rate of the process. The amount of ethene absorbed by
the naphthalene–lithium system in THF (Li:C10H8 = 2:1) in the
presence of toluene is significantly greater (Table 4) than that un-
der the same conditions but in the absence of toluene (Table 1).
Alkylation of toluene with ethene in the naphthalene–sodium
system in THF (Na:C10H8 = 2:1) affords 15% of 11 and 3% of 13 after
24 h (Table 2), and products of the naphthalene alkylation contain
1 (33%) along with small quantities (3%) of 2 and 3 (Table 3). The
replacement of THF by DME leads again to a strong decrease in
the toluene and naphthalene conversion (Tables 2 and 3). The
quantity of absorbed ethene decreases also under these conditions
(Table 4). If [15]crown-5 (1 mol per mol of naphthalene) is added
to the naphthalene–sodium system in THF (Na:C10H8 = 2:1) only
traces of products of the toluene and naphthalene alkylation are
formed after 24 h and the amount of absorbed ethene drops from
2.77 to 0.37 mol per mol of naphthalene.
The naphthalene–potassium system in THF in the presence of
toluene exhibits a low activity in alkylation of both naphthalene
and toluene at 22 °C. When the reaction of ethene with this system
is carried out for 24 h at a K:C10H8 molar ratio of 2:1, the yield of 1
amounts only to 7% based on naphthalene (Table 3) and the con-
version of toluene into alkylation products does not exceed 9%
(8% of 11, 1% of 13; see Table 2). As mentioned above, the interac-
tion of ethene with the naphthalene–potassium system in THF in
the absence of toluene gives 1–3 in a total yield of 85% (Table 1)
under similar conditions. Thus, an introduction of toluene in the
naphthalene–potassium system leads to a strong inhibition of the
process of the naphthalene alkylation. Interestingly, the replace-
ment of THF by DME results here in an increase rather than in a de-
crease in the toluene and naphthalene conversion.
In the case of the naphthalene–sodium system in THF, an addi-
tion of toluene lowers the rate of the naphthalene alkylation as
well. For example, if the reaction with ethene is conducted for
4 h (Na:C10H8 = 2:1) the conversion of naphthalene into 1 in the
absence of toluene attains 31% (Table 1) while in its presence only
20% of 1 are formed (Table 3). Upon an increase in the reaction
time to 24 h, the yields of products of the naphthalene alkylation
in the absence and in the presence of toluene become close to each
other.
An introduction of toluene in the lithium-containing system in
THF (Li:C10H8 = 2:1) increases the yield of 1 but markedly de-
creases the overall yield of higher monoalkylnaphthalenes and
their dihydro derivatives. As a result, the ethene consumption for
the formation of products of the naphthalene alkylation in the
absence of toluene proves here to be considerably greater that that
Ph2 þ 2Li ¢ Ph2gLiþ þ Li ¢ Ph22ꢁ2Liþ
In the case of the naphthalene–lithium system in THF, an addi-
tional contribution to the observed ethene absorption could be
made by the carbolithiation of ethene with the naphthalene dian-
ion [6,12] which is known to be formed in such systems in certain
amounts in the presence of an excess of metallic lithium [18d,19].
Toluene can also be alkylated with ethene in the naphthalene–
alkali metal systems. The reactions proceed at room temperature
and result in the formation of higher monoalkylbenzenes (Table
2). The greatest activity in this process is displayed by the naphtha-
lene–lithium system in THF (Li:C10H8 = 2:1; the C10H8:PhMe ratio
is 1.06:1) which converts toluene into a mixture of n-propylben-
zene (11) (yield 30%), n-pentylbenzene (12) (5%), 3-phenylpentane
(13) (8%) and 3-phenylheptane (14) (5%) in a total yield of 48%
based on toluene (24 h). When the reaction is conducted at a
Li:C10H8 ratio of 1:1 the conversion of toluene into alkylation prod-
ucts sharply falls down, and on using DME as a solvent no toluene
alkylation occurs at all.
In the presence of toluene, naphthalene is also alkylated with
ethene in the naphthalene–lithium system in THF (Li:C10H8
=
2:1). As a result of the reaction, a mixture of 1–8 in 55% overall
Table 2
Table 3
Alkylation of toluene with ethene in the naphthalene–alkali metal systems in THF and
Alkylation of naphthalene with ethene in the naphthalene–alkali metal systems in
DME.a
THF and DME in the presence of toluene.a
M
Li
M:C10H8
(mol/mol)
Solvent Reaction
time (h)
Yield of products
of toluene
Toluene
conversion (%)
M
Li
M:C10H8
(mol/
mol)
Solvent Reaction Yield of products of
time (h) naphthalene alkylation
(%)b
Naphthalene
conversion
(%)
alkylation (%)b
11 12 13 14
1
2 + 3
4
5
7 + 8
2:1
1:1
2:1
THF
THF
DME
THF
THF
DME
THF
DME
24
24
24
4
24
24
24
24
30
9
–
6
15
1
5
–
–
–
–
–
–
–
8
1
–
–
3
–
1
6
5
–
–
–
–
–
–
–
48
10
0
6
18
1
2:1
1:1
2:1
THF
THF
DME
THF
THF
DME
THF
DME
24
24
24
4
24
24
24
24
34
20
22
20
33
8
2
–
–
–
3
–
–
–
13
6
–
–
–
–
–
–
3
–
–
–
–
–
–
–
3
–
–
–
–
–
–
–
55
26
22
20
36
8
Na 2:1
2:1
Na 2:1
2:1
2:1
2:1
2:1
2:1
2:1
2:1
K
8
11
9
17
K
7
29
7
29
a
a
22 °C, 1 atm, 3 mmol of naphthalene, a C10H8:toluene molar ratio is 1.06:1,
[C10H8]o = 2 M.
22 °C, 1 atm, 3 mmol of naphthalene, a C10H8:toluene molar ratio is 1.06:1,
[C10H8]o = 2 M.
b
b
Based on toluene.
Based on naphthalene.

1462
S. Rummel et al. / Journal of Organometallic Chemistry 694 (2009) 1459–1466
in the presence of toluene (see Tables 1 and 4). In all lithium-, so-
dium- and potassium-based systems, the amount of absorbed eth-
ene in the presence of toluene significantly exceeds the ethene
quantity consumed for the alkylation (Table 4). Note also, the
alkylation of naphthalene proceeds, as a rule, more efficiently than
the toluene alkylation.
A treatment of biphenyl, phenanthrene, trans-stilbene, pyrene
and anthracene with alkali metals in THF also gives systems
Table 4
Comparison of the amount of absorbed ethene with its consumption for the formation of products of toluene and naphthalene alkylation in the naphthalene–alkali metal systems
in THF and DME.a
M
M:C10H8 (mol/mol)
Solvent
Reaction time (h)
Absorbed C2H4 (mmol)
C2H4 consumption for alkylation
Toluene
Total (mmol)
Naphthalene
(mmol)
(mol/mol PhMe)
(mmol)
(mol/mol C10H8)
Li
2:1
1:1
2:1
2:1
2:1
2:1
2:1
2:1
THF
THF
DME
THF
THF
DME
THF
DME
24
24
24
4
24
24
24
24
7.25
2.20
1.47
1.20
2.77
0.94
1.21
2.84
2.01
0.31
0
0.17
0.59
0.03
0.28
0.65
0.71
0.11
0
0.06
0.21
0.01
0.10
0.23
2.40
0.96
0.66
0.60
1.08
0.24
0.21
0.87
0.80
0.32
0.22
0.20
0.36
0.08
0.07
0.29
4.41
1.27
0.66
0.77
1.67
0.27
0.49
1.52
Na
K
a
22 °C, 1 atm, 3 mmol of naphthalene, a C10H8:toluene molar ratio is 1.06:1, [C10H8]o = 2 M.
Table 5
The effect of the nature of aromatic hydrocarbon (ArH) on the toluene alkylation with ethene in the ArH–alkali metal systems in THFa
ArH
M
M:ArH (mol/mol)
Absorbed C2H4 (mmol)
Yield of alkylation products (%)b
C2H4 consumption for alkylation
Toluene conversion (%)
11
12
13
14
15
16
(mmol)
(mol/mol PhMe)
Biphenyl
Li
2:1
1:1
2:1
1:1
2:1
1:1
2:1
2:1
3:1
3:1
3:1
3:1
2:1
3:1
2:1
2:1
3:1
2:1
3.87
3.40
2.24
2.62
7.25
2.21
2.77
1.21
5.41
5.29
5.42
8.65
6.33
5.09
2.62
1.20
7.59
4.74
25
21
44
31
30
9
5
–
–
–
5
–
–
–
4
–
–
6
–
6
–
–
6
4
2
3
4
2
8
1
3
1
3
1
24
12
11
4
–
–
5
3
–
–
–
–
5
–
–
–
2
–
–
6
–
3
–
–
4
2
–
–
–
–
–
–
–
–
–
–
–
2
–
–
–
–
2
–
–
–
–
–
–
–
–
–
–
–
–
2
–
2
–
–
–
–
1.10
0.76
1.47
0.99
2.01
0.31
0.59
0.28
1.33
0.34
1.70
2.77
1.25
2.07
0.40
<0.03
2.09
1.33
0.39
0.27
0.52
0.35
0.71
0.11
0.21
0.10
0.47
0.12
0.60
0.98
0.44
0.73
0.14
<0.01
0.74
0.47
32
24
48
33
48
10
18
9
36
11
36
58
33
51
14
<1
51
36
Na
Li
Naphthalene
Phenanthrene
Na
K
Li
Na
K
Li
15
8
27
10
12
30
22
36
14
<1
34
27
Stilbene
Pyrene
Li
Na
Li
Anthracene
a
22 °C, 1 atm, 24 h, 3 mmol of ArH, an ArH:PhMe molar ratio is 1.06:1. With the exception of naphthalene, the initial ArH concentration is 1.67 M, [C10H8]o = 2 M.
Based on toluene.
b
Table 6
The effect of LiI on the toluene alkylation with ethene in the ArH–lithium systems in THF.a
ArH
Li:ArH (mol/mol) [LiI]o (M) Absorbed C2H4 (mmol) Yield of alkylation products
(%)b
C2H4 consumption for toluene
alkylation
Toluene conversion (%)
11 12 13 14 15 16 (mmol)
(mol/mol PhMe)
Biphenyl
2:1
2:1
2:1
2:1
2:1
–
0.28
–
0.33
0.67
–
0.56
–
3.87
7.80
7.25
9.61
9.73
5.41
6.92
8.65
9.61
7.59
6.68
25
34
30
30
33
27
35
30
24
34
29
5
6
5
6
6
4
6
6
5
6
4
2
4
8
5
8
3
5
12
17
5
–
3
5
4
5
2
4
6
6
4
2
–
–
–
2
2
–
2
2
2
2
–
–
–
–
5
–
–
–
2
2
–
–
1.10
1.78
2.01
2.55
2.32
1.33
2.12
2.77
2.83
2.09
1.39
0.39
0.63
0.71
0.90
0.82
0.47
0.75
0.98
1.00
0.74
0.49
32
47
48
52
54
36
52
58
56
51
38
Naphthalene
Phenanthrene 3:1
3:1
Stilbene
3:1
3:1
3:1
3:1
0.56
–
0.56
Anthracene
3
a
22 °C, 1 atm, 24 h, 3 mmol of ArH, an ArH:PhMe molar ratio is 1.06:1. With the exception of naphthalene, the initial ArH concentration is 1.67 M, [C10H8]o = 2 M.
Based on toluene.
b

S. Rummel et al. / Journal of Organometallic Chemistry 694 (2009) 1459–1466
1463
capable of catalyzing the alkylation of toluene with ethene at room
temperature. As seen from Table 5, in the case of lithium, the activity
of the examined aromatic hydrocarbons in the toluene alkylation
with ethene falls in the order: stilbene > pyrene ꢀ anthra-
cene > naphthalene > phenanthrene > biphenyl. The highest effi-
ciency is exhibited by the stilbene-based system which converts
toluene into a mixture of 11–14, n-heptylbenzene (15) and 5-phen-
ylnonane (16) in a yield of 58% (Li:stilbene = 3:1; 24 h). The least
alkylation rate is observed for the biphenyl–lithium system.
With metallic sodium, the biphenyl-, phenanthrene- and pyr-
ene-containing systems were tested and it was found that in this
case the examined aromatic hydrocarbons are arranged in the fol-
lowing sequence according to their activity in the toluene alkyl-
supports this conclusion. Benzene is inactive in the alkylation with
ethene at room temperature.
A comparison of the alkylation reactions found with the above-
mentioned reactions of the H/D exchange of hydrocarbons in the
naphthalene–sodium system in THF [4] shows that there is a num-
ber of common features between these two types of the processes.
The both reactions are strongly accelerated in the presence of the
solid phase of alkali metal. In both cases, the replacement of THF
by DME in the naphthalene–sodium systems decreases sharply
the reaction rate (up to zero in the case of the H/D exchange). Fi-
nally, the both processes are dramatically inhibited by additives
of [15]crown-5.
On the basis of the results obtained on studying the H/D ex-
change of hydrocarbons in the naphthalene–sodium system, it
has been suggested [4] that this process proceeds through the fol-
lowing main steps:
ation:
biphenyl > naphthalene > phenanthrene > pyrene.
The
greatest toluene conversion is reached here for the biphenyl-based
system. On using pyrene, the replacement of lithium by sodium
leads to a practically full loss of the activity in the toluene alkyl-
ation. In all cases, with the exception of biphenyl, the lithium-con-
taining systems are noticeably more efficient than the
corresponding sodium-containing systems. In the case of biphenyl,
the use of sodium instead of lithium gives markedly higher toluene
conversion. In all systems, the presence of the solid phase of alkali
metal in a mixture considerably increases the rate of the toluene
alkylation.
The efficiency of the alkylation of toluene with ethene in the
biphenyl–lithium and phenanthrene–lithium systems in THF can
be substantially augmented if the reactions are carried out in the
presence of lithium iodide (Table 6). For example, an introduction
of LiI into the phenanthrene–lithium system enhances the toluene
conversion into alkylation products from 36% to 52% (24 h). In the
case of the naphthalene– and stilbene–lithium systems, additives
of LiI little affect the alkylation rate. An addition of LiI to the
anthracene–lithium system inhibits the process of the alkylation
(Table 6).
(1) Generation of atomic sodium in the C10H8–Na system due to
the reactions (a),(b),(c):
Namet þ ArHgNaþ ¢ NaþArHg þ Naat
ArHgNaþ þ ArHgNaþ ¢ ArH þ NaþArHg þ Naat
ArHgNaþ ¢ ArH þ Naat
ðaÞ
ðbÞ
ðcÞ
ArH ꢁ naphthalene
(2) Agglomeration of atomic sodium into sodium clusters [Nan]
stabilized by the formation of surface complexes with
naphthalene.
(3) Reversible cleavage of C–H and C–D bonds of hydrocarbons
on the surface of sodium clusters, resulting in the hydro-
gen–deuterium exchange.
In homogeneous medium, i.e. at a C10H8:Na molar ratio of 1:1,
atomic sodium could be formed due to reactions (b) and (c). When
an excess of the alkali metal is present in a mixture, the conditions
for occurrence of reaction (a) are established, which leads to an in-
crease in the content of sodium clusters in the system and, as a
consequence, to an increase in the rate of the H/D exchange. A
sharp retardation of the H/D exchange reaction on the use of
DME instead of THF and also on an addition of [15]crown-5 has
been explained by the necessity of the existence of intermediate
surface complexes of sodium atoms with naphthalene (or other
hydrocarbon molecules) as contact ion pairs. The formation of such
ion pairs could provide a direct contact of the reacting hydrocarbon
with active metallic centres on the surface of the cluster. As is
known, sodium naphthalide in a DME solution, in contrast to so-
dium naphthalide in THF, exists at room temperature as solvent-
separated ion pairs [1,19,21]. A conclusion has also been made that
the naphthalene dianion can not play the part of the active species
in the H/D exchange because metallic sodium in contrast to lithium
metal does not form the corresponding dianion with naphthalene
in THF at 22 °C [19].
3. Conclusion
Systems based on naphthalene and metallic lithium, sodium or
potassium in THF are able to induce alkylation of naphthalene and
toluene with ethene at room temperature. As a result of the reac-
tions, naphthalene is converted into linear 1-alkylnaphthalenes
C10H7(CH2CH2)nH (Li, n = 1–4; Na and K, n = 1) and their dihydro
derivatives while toluene produces linear and
a-branched higher
monoalkylbenzenes. A treatment of biphenyl, anthracene, trans-
stilbene, phenanthrene and pyrene with alkali metals in THF also
yields systems capable of catalyzing the alkylation of toluene with
ethene at 22 °C to afford linear and
a-branched monoalkylbenz-
enes. In all cases, the use of lithium-containing systems favours
the formation of products with longer alkyl chains. The greatest
activity in the naphthalene alkylation is exhibited by the naphtha-
lene–potassium system which gives 85% naphthalene conversion
into alkylation products after 24 h. The stilbene–lithium system
shows the highest activity in the toluene alkylation (the toluene
conversion is 58% after 24 h). In the case of toluene, the C–H bonds
of its methyl group are involved in the reaction with ethene, there-
by giving rise to two families of the alkylation products, viz. linear
A similar ‘‘cluster” mechanism can be proposed for the above-
described reactions of the naphthalene and toluene alkylation with
ethene. As in the case of the H/D exchange, this process starts, pre-
sumably, with the formation of atomic alkali metal by reactions of
the type (a),(b),(c). In the lithium metal-based systems containing
lithium iodide, atomic lithium could also be generated due to the
reaction between Li and LiI.
C3, C5, C7 and
a-branched C5, C7 and C9 monoalkylbenzenes. The
yields of these products and their ratios depend on the nature of
the system used. The process of the alkylation is accompanied by
absorption of large amounts of ethene. As is known, THF is splitted
in systems of such a type into acetaldehyde enolate and ethene at
room temperature [6,18d,20], and, naturally, this autogenously
produced ethene can also be involved in the naphthalene and
toluene alkylation. The formation of small amounts of 1-ethyl-
naphthalene (2%) in the interaction of THF with the naphtha-
lene–lithium system (Li:C10H8 = 2.35:1) for 24 h at 25 °C [18d]
Limet þ IꢁLiþ ¢ LiþIꢁ þ Liat
This Li–LiI system can be considered as an analogue of the well-
known Mg–MgI2 system in ether wherein the formation of magne-
sium subiodide MgI was postulated [22,23] in order to explain the
activating effect of MgI2 on metallic magnesium.

1464
S. Rummel et al. / Journal of Organometallic Chemistry 694 (2009) 1459–1466
Mgmet þ MgI2 ¢ 2MgI
made by the above-mentioned rapid, direct protonation of the
intermediate surface [M]-(CH2CH2)nR species with THF.
In the next stages, the atomic metal species formed agglomerate
into the corresponding clusters which then reversibly cleave the
reactive C–H bonds of a hydrocarbon (RH) to afford surface [M]-R
and [M]-H groups. The subsequent ethene insertion into the alkali
metal–carbon bonds arising on the surface of the clusters gives rise
(after the reductive elimination) to the products of the naphtha-
lene and toluene alkylation with linear alkyl chain (Scheme 1).
One may suggest that in the case of toluene, one of the C–H
bonds of the benzyl CH2 group in the resulting linear products,
PhCH2(CH2CH2)nH, is also able to undergo the metallation, yielding
surface [M]-CH(Ph)(CH2CH2)nH and [M]-H moieties. These moie-
Phenyl ring of toluene, in contrast to toluene methyl group, is
not alkylated with ethene in the above ArH–alkali metal systems
although both these groups are involved in the H/D exchange with
naphthalene rings of sodium naphthalide in THF [4]. This fact can
be explained by a competition between ethene and the aromatic
substrate for active metallic sites of the clusters. Apparently, in
the case of the C–H bonds of toluene phenyl group, which are con-
siderably less acidic than those of toluene methyl group, such a
competition with ethene results in a total inhibition of the alkyl-
ation reaction. The same reason leads, presumably, to inactivity
of benzene in the alkylation despite the fact that benzene also
undergoes the H/D exchange with naphthalene rings in the naph-
thalene–sodium system in THF (see above and [4]).
The formation of alkali metal clusters in the gas phase and in so-
lid inert gas matrices is now well documented (see e.g. [27–30]).
Data of quantum-chemical calculations of such clusters are also
available (see e.g. [28–33]). Recently, the metal vapour synthesis
(MVS) and characterization of the cluster aryl Grignard reagents
PhMg4X (X = F, Cl, Br) containing four magnesium atoms per one
phenyl group and one halogen atom have been reported [34,35].
The clusters are quite stable under usual conditions in a haloben-
zene solution and are easily transformed into the corresponding
cluster alkyl Grignard reagents RMg4Cl (R = C7H15, C8H17) in the
interaction with alkyl chlorides RCl. It has also been shown [36]
that under MVS conditions in the magnesium–anthracene system
the resulting magnesium clusters are inserted into C–H bonds at
the 9- and 10-positions of anthracene to afford cluster anthrace-
nylmagnesium hydrides: 9-C14H9Mg4H and 9,10-C14H8(Mg4H)2.
These compounds can be considered as models of the aforemen-
tioned hypothetical [M]-R and [M]-H species which could be gen-
erated from naphthalene and toluene on the surface of alkali metal
clusters in the course of the alkylation.
ties could be the source of a-branched higher monoalkylbenzenes
in the subsequent reaction with ethene (Scheme 2). The ability of
benzyllithium and phenyllithium as well as primary and secondary
alkyllithium species to add to ethene in THF at room temperature
has earlier been reported by Maercker et al. [14,24].
The absence of
the naphthalene alkylation can be explained by a strong decrease
in the rate of the metallation of the -CH2 group in the linear 1-
a-branched 1-alkylnaphthalenes in products of
a
alkylnaphthalenes, 1-C10H7(CH2CH2)nH, because of the steric hin-
drances created by the neighbouring peri-hydrogen atom of the
naphthalene ring (cf. [25]).
The process of the reductive elimination leads to a termination
of the growing alkyl chain due to its coupling with the hydrogen
atom of a surface [M]-H group. The appearance of these [M]-H
groups on the cluster surface can result from the C–H bond cleav-
age of the aromatic substrate as well as of the THF and ethene mol-
ecules. The occurence of the hydrogen–deuterium exchange
between THF and naphthalene and also between ethene, THF and
naphthalene in the naphthalene–sodium system [4] supports this
assumption. The surface [M]-H groups could also be a source of
hydrogen for the formation of dihydro derivatives of 1-alkylnaph-
thalenes in the naphthalene alkylation reactions. Another pathway
of a termination of a growing alkyl chain in the process of the
alkylation might consist in a direct protonation of the surface
[M]-(CH2CH2)nR and similar metal organyl moieties with THF (cf.
[1]). As is known, alkyl derivatives of alkali metals are unstable
in THF at room temperature and, as a rule, rapidly undergo the pro-
tolysis with THF molecules to give the corresponding free hydro-
carbons (see e.g. [14,26]).
Coupling products of the type R–R and R(CH2CH2)nR either are
detected in the reaction solutions only in trace amounts (1,10-
binaphtyl, 1-C10H7(CH2CH2)CH2Ph (17), 1-C10H7(CH2CH2)2CH2Ph
(18), dibenzyl) or are not detected at all, which can be connected
with a large excess of THF relative to the starting hydrocarbon. In-
deed, because THF (along with RH) is proposed to be one of the
sources of the [M]-H bonds on the cluster surface, one may assume
that the number of such bonds, for the above reason, will be signif-
icantly greater than that of the [M]-R bonds, and, correspondingly,
the rate of the formation of the alkylation products R(CH2CH2)nH in
the reaction with ethene will be significantly higher than that of
the coupling products R–R and R(CH2CH2)nR. An additional contri-
bution to the predominant formation of R(CH2CH2)nH could be
For naphthalene and lithium in THF and for other arenes capa-
ble of forming dianionic adducts with alkali metals in this solvent,
an alternative reaction mechanism with the participation of the
corresponding arene dianion as the active species should also be
discussed.
In the case of the naphthalene alkylation, the proposed reaction
Scheme 3 is based on the ability of the lithium salts of the naphtha-
lene, biphenyl and phenanthrene dianions to add to some alkenes,
including ethene, in THF at 25 °C [6,12]. The mechanism suggests
fast protonation of the primary alkyllithium centre in the resulting
products of the ethene insertion with THF [14,26] or/and some
other quenchable component of the reaction medium, for instance,
with ethene (cf. [12]). For the formation of 1-alkylnaphthalenes in
the course of the alkylation, it is necessary also to postulate within
the framework of this mechanism the elimination of lithium hy-
dride from the end products of the carbolithiation although it is
not quite clear how efficiently such a process might occur under
our experimental conditions.
The role of the naphthalene dianion in the toluene alkylation
could consist here in the reversible metallation of the toluene
2[M] + PhCH (CH CH ) H
[M]–CH(Ph)(CH CH ) H + [M]–H
2 2 n
2
2
2 n
2[M] + RH
[M]–R + [M]–H
[M]–(CH CH ) R
(CH2CH2) H
n
_
PhCH
[M]–R + nCH =CH
2
CH(Ph)(CH2CH2)nH + mCH2=CH2
[M]
2
2
2 n
(CH2CH2) [M]
m
[M]–(CH CH ) R + [M]–H
2[M] + R(CH CH ) H
2 2 n
2
2 n
(CH2CH2)nH
(CH2CH2)nH
(CH2CH2)m[M]
_
+ 2[M]
PhCH
+ [M]
PhCH
H
(CH2CH2) H
m
R = 1-C H , PhCH
2
10
7
Scheme 1.
Scheme 2.

S. Rummel et al. / Journal of Organometallic Chemistry 694 (2009) 1459–1466
1465
H
(CH2CH2)nLi
2
[H+]
2Li+ + nCH2=CH2
Li+
(CH2CH2)nH
(CH2CH2)nH
H
Li+
+
LiH
Scheme 3.
H
H
2−
2Li+
Li+ + PhCH2Li
+ PhCH3
[H+]
H
PhCH2(CH2CH2) Li
PhCH2(CH2CH2) H
n
PhCH2Li + nCH2=CH2
n
H
2−
2Li+
Li+ + PhCH(Li)(CH2CH2) H
n
+ PhCH2(CH2CH2) H
n
[H+]
(CH2CH2) H
(CH2CH2) H
n
n
PhCH
PhCH
PhCH(Li)(CH2CH2) H + mCH2=CH2
n
(CH2CH2) Li
m
(CH2CH2) H
m
Scheme 4.
methyl group to give benzyllithium which then reacts with ethene
producing linear higher monoalkylbenzenes. The formation of
branched monoalkylbenzenes could proceed in a similar fashion
(Scheme 4).
(THF, DME) or over sodium (toluene) under Ar. Commercial naph-
thalene, biphenyl, phenanthrene, trans-stilbene, pyrene and
anthracene of high quality as well as [15]crown-5 were used with-
out further purification. Metallic lithium, sodium and potassium
were introduced into the reactions in the form of the particles of
the size: ca. 3 ꢂ 2 ꢂ 0.3 mm in the case of lithium and ca.
4 ꢂ 3 ꢂ 0.5 mm in the case of sodium and potassium. Solutions of
LiI in THF were prepared by the reaction of metallic lithium with io-
dine in THF under Ar. The reaction products were analysed by GLC
with temperature programming (160 °C, 10 min; 160–300 °C,
10 °C/min; 300 °C, 40 min) on a Crompack CP 9001 chromatograph
a
-
It should be noted however that although as a whole this alter-
native mechanism of the alkylation satisfactorily explains the re-
sults obtained for the naphthalene–lithium system, a problem
arises in the case of the naphthalene–sodium system because of
inability of metallic sodium to form the dianion with naphthalene
in THF at room temperature in any detectable amounts [19]. For
metallic potassium, there are also no unambiguous evidences for
the formation of the corresponding naphthalene dianion in a THF
solution at 22 °C. According to Ref. [37], dipotassium naphthalene,
prepared by condensation of potassium and naphthalene vapors,
instantly and completely decomposes into monopotassium naph-
thalene and metallic potassium on dissolution in THF. Of course,
it must not be ruled out that some tiny quantities of the naphtha-
lene dianion are present indeed in the naphthalene–sodium and
naphthalene–potassium systems in THF. However, it is unclear
whether such negligible concentrations of the dianion can provide
those alkylation rates which were observed at room temperature
in our experiments.
equipped with
a flame ionization detector and a DB5 MS
(30 m ꢂ 0.25 mm) capillary column (the internal standard – dode-
cane). The GLC/MS analyses were performed on a Trio 1000, FISONS
instrument. The most part of the experiments was duplicated or
triplicated showing reasonably good reproducibility. When the
naphthalene–potassium system in THF was used for the naphtha-
lene alkylation in the absence of toluene the reproducibility was
somewhat worse and here the results obtained were averaged for
five runs (1 – 83 6%), 2 + 3 – 2 1%).
4.1. Product identification
For the elucidation of the genuine mechanism of the naphtha-
lene and toluene alkylation in the above-described systems, special
studies are required.
Compounds 1, 4, 5, 11, 12 and 15 were identified by GLC and GLC/
MS using authentic samplesof these compounds. Products13 and 14
as well as 1,10-binaphthyl and dibenzyl were identified on the basis
of coincidence of their mass spectra with the corresponding litera-
ture data [38]. The conclusion on the nature of other products is
based on the analysis of their mass spectra. The most important
characteristics of the mass spectra recorded for these products are
given below. Compound 2, m/z: 158 ([M]+, 53%), 129 ([MꢁEt]+,
100%), 128 ([C10H8]+, 65%). Compound 3, m/z: 158 ([M]+, 63%), 129
4. Experimental
The experiments were carried out in an Ar atmosphere with
careful exclusion of air oxygen and moisture using standard Shlenk
techniques. THF, DME and toluene were purified in the usual man-
ner and freshly distilled prior to use from sodium/benzophenone

1466
S. Rummel et al. / Journal of Organometallic Chemistry 694 (2009) 1459–1466
([MꢁEt]+, 100%), 128 ([C10H8]+, 92%). Compound 6, m/z: 240 ([M]+,
12%), 142 ([MꢁC7H14]+, 28%), 141 ([MꢁC7H15]+, 100%), 128
([C10H8]+, 14%), 115 ([MꢁC7H15ꢁC2H2]+, 79%). Compound 7, m/z:
214 ([M]+, 12%), 185 ([MꢁEt]+, 30%), 157 ([MꢁBu]+, 22%), 129
([MꢁHex]+, 100%), 128 ([C10H8]+, 80%). Compound 8, m/z: 214
([M]+, 8%), 185 ([MꢁEt]+, 14%), 157 ([MꢁBu]+, 16%), 129 ([MꢁHex]+,
100%), 128 ([C10H8]+, 86%). Compound 9, m/z: 242 ([M]+, 10%), 213
([MꢁEt]+, 35%), 185 ([MꢁBu]+, 11%), 157 ([MꢁHex]+, 31%), 129
([MꢁOct]+, 100%), 128 ([C10H8]+, 93%). Compound 10, m/z: 242
([M]+, 13%), 213 ([MꢁEt]+, 44%), 185 ([MꢁBu]+, 15%), 157
([MꢁHex]+, 42%), 129 ([MꢁOct]+, 84%), 128 ([C10H8]+, 100%). Com-
pound 16, m/z: 204 ([M]+, 8%), 147 ([MꢁBu]+, 9%), 91 ([C7H7]+,
100%). Compound 17, m/z: 246 ([M]+, 15%), 155 ([MꢁPhCH2]+,
10%), 142 ([MꢁPhCHCH2]+, 38%), 141 ([MꢁPh(CH2)2]+, 43%), 128
([C10H8]+, 15%), 115 ([MꢁPh(CH2)2ꢁC2H2]+, 67%), 91 ([C7H7]+,
100%). Compound 18, m/z: 274 ([M]+, 14%), 155 ([MꢁPh(CH2)3]+,
12%), 142 ([MꢁPh(CH2)2CHCH2]+, 37%), 141 ([MꢁPh(CH2)4]+, 64%),
128 ([C10H8]+, 12%), 115 ([MꢁPh(CH2)4ꢁC2H2]+, 70%), 91 ([C7H7]+,
100%).
2% of 2 and 3, 13% of 4, 3% of 5, 3% of 7 and 8); the toluene conver-
sion is 48% (30% of 11, 5% of 12, 8% of 13, 5% of 14).
Other experiments on the toluene and naphthalene alkylation
were carried out by similar procedures. The results are summa-
rized in Tables 1–6.
References
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4.2. Alkylation of naphthalene in the C10H8–Na system
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Naphthalene (0.384 g, 3 mmol), THF (1.5 ml), metallic sodium
(0.138 g, 6 mmol) and dodecane (0.0533 g) were placed in the
Schlenk tube under Ar. The content of the Schlenk tube was cooled
with liquid dinitrogen and, after removal of the argon by evacua-
tion, the mixture was unfrozen to room temperature. Then ethene
was introduced from an attached mercury burette and the reaction
mixture was stirred at room temperature on a magnetic stirrer. The
course of the reaction was monitored based on ethene absorption.
After 24 h, when the amount of absorbed ethene attained 0.73 mol
per mol of naphthalene (ca. 49 ml, STP), the mixture was diluted
with 1.5 ml of THF and analysed by GLC and GLC/MS. The analyses
showed the presence of 1 (35% based on naphthalene) together
with small amounts (2%) of 2 and 3 in the reaction solution. The
overall conversion of naphthalene is 37%.
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4.3. Alkylation of toluene and naphthalene in the C10H8–Li system
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Naphthalene (0.384 g, 3 mmol), THF (1.2 ml), metallic lithium
(0.042 g, 6 mmol), toluene (0.3 ml, 2.84 mmol) and dodecane
(0.0485 g) were charged under Ar in the Shlenk tube and, after
replacement of the argon atmosphere by ethene (from an attached
mercury burette; see above), the mixture was stirred at room tem-
perature on a magnetic stirrer. After 24 h, when the amount of ab-
sorbed ethene reached 2.42 mol per mol of naphthalene (ca.
163 ml, STP), the reaction solution was diluted with 1.5 ml of
THF and analysed by GLC and GLC/MS for the content of products
of the naphthalene and toluene alkylation. The results of the anal-
yses are as follows: the naphthalene conversion is 55% (34% of 1,
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