Gas-phase pyrolytic reaction of 3-anilino-1-propanol derivatives: kinetic and mechanistic study

Article abstract of DOI:10.1016/j.tet.2007.03.090

3-Anilino-1-propanol derivatives 4a-c, 5a-c, 6a-c containing primary, secondary, and tertiary alcohols and PhNH, PhNMe, and (Ph)₂N were prepared and subjected to gas-phase pyrolysis in a static reaction system. The pyrolytic reactions were homogeneous and followed a first-order rate equation. Reactions took place by retro-ene process, with the exception of compounds 5a and 5b. Analysis of the pyrolysate showed the products to be N-substituted aniline and carbonyl compounds. The kinetic results and product analysis of each of the nine investigated 3-amino alcohols are rationalized in terms of a plausible transition state for the elimination pathway.

Full text of DOI:10.1016/j.tet.2007.03.090

Tetrahedron 63 (2007) 4768–4772
Gas-phase pyrolytic reaction of 3-anilino-1-propanol derivatives:
kinetic and mechanistic study
*
M. R. Ibrahim, N. A. Al-Awadi, Y. A. Ibrahim, M. Patel and S. Al-Awadi
Chemistry Department, Kuwait University, PO Box 5969, Safat 13060, Kuwait
Received 4 November 2006; revised 23 February 2007; accepted 15 March 2007
Available online 18 March 2007
Abstract—3-Anilino-1-propanol derivatives 4a–c, 5a–c, 6a–c containing primary, secondary, and tertiary alcohols and PhNH, PhNMe, and
(Ph)2N were prepared and subjected to gas-phase pyrolysis in a static reaction system. The pyrolytic reactions were homogeneous and
followed a first-order rate equation. Reactions took place by retro-ene process, with the exception of compounds 5a and 5b. Analysis of
the pyrolysate showed the products to be N-substituted aniline and carbonyl compounds. The kinetic results and product analysis of each
of the nine investigated 3-amino alcohols are rationalized in terms of a plausible transition state for the elimination pathway.
Ó 2007 Elsevier Ltd. All rights reserved.
1. Introduction
of the corresponding a-amino acid and ethylene,2 the amino
acid intermediate then undergoes an extremely rapid decarb-
oxylation process (Scheme 3).
We have recently shown that the thermal gas-phase elimina-
tion reaction of 2-N-arylaminopropanoic acid 1 and 3-N-
arylaminopropanoic acid 2 are homogeneous and free from
catalytic and radical pathways. The pyrolysate of 1 showed
the elimination products to be CO, CH3CHO, and aniline
(Scheme 1), while the pyrolysate of 2 reveals the formation
of acrylic acid in addition to aniline.1
H
O
C
H3C
H3C
O
C
CH2
CH2
H3C
H3C
N CH2
OCH2CH3
N CH2
O
3
O
H3C
H3C
H3C
N
CO2
CH3
COOH
CH
NH
H3C
H3C
N
CH3
CH2
H C CH2
2
+
N
O
H3C
H
H
CH3 CH CO
CH3 CH CO
ArNH2
+
O
CO
ArN
H
O
Scheme 3. Pyrolysis of ethyl N,N-dimethylglycinate.
H
X
1
H3C CHO
In this study, we look at the pyrolysis reaction of 3-amino
primary, secondary, and tertiary propyl alcohols, the amino
substituents are: PhNH- (4a–c), PhNMe- (5a–c), and
(Ph)2N- (6a–c) (Table 1).
Scheme 1. Pyrolysis of 2-N-arylaminopropanoic acid.
This together with theoretical calculation on 2 suggest a reac-
tion pathway involving s four-membered transition state
(Scheme 2).
Table 1. Substrates under study
Z
C
G
X
H
H
N CH2CH2
OH
ArN
H
ArN
H
ArNH2
CH2 CHCOOH
+
Y
COOH
COOH
Compound
X
Y
Z
G
2
4a
4b
4c
5a
5b
5c
6a
6b
6c
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
H
H
H
Me
Me
Me
Ph
Ph
Ph
H
H
Me
H
H
Me
H
H
Me
H
Scheme 2. Pyrolysis of 3-N-arylaminopropanoic acid.
Me
Me
H
Me
Me
H
The gas-phase elimination reaction of ethyl N,N-dimethyl-
glycinate 3 in a static reaction system leads to the formation
Keywords: 3-Anilino-1-propanol; Pyrolysis; Kinetics; Reaction mechanism.
* Corresponding author. Tel.: +965 4985537; fax: +965 4816482; e-mail:
nouria@kuc01.kuniv.edu.kw
Me
Me
0040–4020/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2007.03.090

M. R. Ibrahim et al. / Tetrahedron 63 (2007) 4768–4772
4769
2. Results and discussion
primary one. The rate enhancement of 850 produced by elec-
tron-donating groups (Z and G¼Me) in 4c over 4a (Z and
G¼H) is consistent with polarization of the O–C bond creat-
ing Cd+–Odꢀ. The reactivity order of 4b (Z¼H, G¼Me) over
4a (Z and G¼H) could be rationalized by the same effect of
the methyl group as an electron-donating group.
2.1. Synthesis
Substrates 4a–c, 5a–c, and 6a–c were prepared and fully
characterized by NMR and MS as described in Section 3.
2.2. Pyrolysates
The effect of methylation has been observed in the following
series: ethyl, isopropyl, tert-butyl acetate pyrolysis and ex-
plained in terms of increasing stabilization of the incipient
carbocation.3
Reaction products for complete pyrolysis were qualitatively
and quantitatively obtained for all the nine substrates in
a sealed-tube pyrolyser (static method) at temperatures ex-
ceeding those used in the kinetic investigations (Table 2).
The static-method reactions were used to allow ample resi-
dence time to ensure maximum pyrolysis. The constituents
of the pyrolysates obtained by this method were isolated us-
ing preparative liquid chromatography and analyzed using
GC–MS and 1H NMR techniques.
2.3.2. 3-N-Methylanilino-1-propanol 5a, 3-N-methyl-
anilino-2-butanol 5b, and 3-N-methylanilino-2-methyl-
2-butanol 5c. The pyrolysates from the pyrolytic reaction
of substrates 5a and 5b were ascertained to be dimethylani-
line PhN(Me)2, together with CH3CHO and (Me)2CO from
5a and 5b, respectively. The reaction pathway shown in
Scheme 5 is compatible with the products of pyrolysis.
Table 2. Pyrolysis products and % yield
No.
Compound
Product/% yield
CH2O/28 CH2]CH2
Z
Z
O
C
Me
G
G
4a PhNH(CH2)3OH
PhNH2/85
PhNH2/51
Me
Ph
Me
Ph
+
PhNCH2
H
CH3
G
PhNH(CH2)2CHCH3
N
O
N
O
4b
CH3CHO/46
(CH3)2CO/20
H
H
OH
PhNH(CH2)2CH(CH3)2
4c
PhNH2/74
PhN(Me)2
OH
-1
k600K (s )
PhN(CH2)3OH
Z
G
5a
PhNMe2/76 CH3CHO/42
PhNMe2/82 (CH3)2CO/25
PhNHMe/68 (CH3)2CO/32
5.22 x 10-4
1.17 x 10-3
Me
H
H
H
5a
5b
PhN(CH2)2CHCH3
Me
5b
Me
PhN(CH2)2CH(CH3)2
Me OH
OH
Scheme 5.
5c
6a
6b
Changing G from H in 5a to Me in 5b did not enhance the
reaction rate considerably, which could be justified by the
more important rate controlling factor of protophilic attack
by the nitrogen atom on the hydrogen of the hydroxyl group.
Comparable reactivity of 5a and 5b supports this suggestion,
as the basicity of the nitrogen atom involved in the reaction
is the same in both substrates 5a and 5b.
(Ph)2N(CH2)3OH
Ph2NH/88
Ph2NH/64
CH2O/8
CH2]CH2
(Ph)2N(CH2)2CHCH3
OH
CH3CHO/26
(Ph)2N(CH2)2CH(CH3)2
OH
6c
Ph2NH/85
(CH3)2CO/30
The pyrolysates from the pyrolytic reaction of the substrate
5c were identified as N-methylaniline and acetone. Forma-
tion of these products can be explained in terms of a six-
membered transition state (Scheme 6).
2.3. Reaction mechanism and molecular reactivities
2.3.1. 3-Anilino-1-propanol 4a, 3-anilino-2-butanol 4b,
and 3-anilino-2-methyl-2-butanol 4c. Each of the 3-anilino
alcohols eliminates aniline and ethylene together with a car-
bonyl compound CH2O, CH3CHO, and (CH3)2CO from 4a,
4b, and 4c, respectively. Identification of these pyrolysis
products suggest the reaction pathway shown in Scheme 4.
Me
PhN
Me
PhN
PhNHMe
+
H2C CH2
Me
Me
Me
Me
H
H
O
O
+
O
O
C
H
H
PhN
PhN
5c
Z
Z
PhNH2 H C CH2
+
+
2
H
H
G
Z
C
O
O
-1
k600K (s ) = 5.02 x 10-2
Me
Me
G
G
-1
k600K (s )
Z
G
Scheme 6.
5.95 x 10-5
1.74 x 10-3
5.06 x 10-2
H
H
H
4a
4b
4c
Me
Me
The only structural feature which distinguishes 5c from 5a
and 5b is the two electron-donating groups, Z¼G¼Me in
5c, this has not only produced rate enhancement, but also
changed the reaction pathway.
Me
Scheme 4. Reaction pathway and first-order rate constant at 600 K for the
pyrolytic reaction of 4a–c.
The pyrolysis of the 3-amino tertiary alcohol is faster
than the secondary alcohol, which in turn is faster than the
2.3.3. 3-N,N-Diphenylamino-1-propanol 6a, 3-N,N-di-
phenylamino-2-butanol 6b, and 3-N,N-diphenylamino-

4770
M. R. Ibrahim et al. / Tetrahedron 63 (2007) 4768–4772
Ph
respectively) suggesting a reaction pathway shown in
Scheme 7.
Ph
PhN
PhNHPh
+
H2C CH2
Ph
N
H
Z
Z
H
O
O
The two phenyl groups at the nitrogen in the substrates 6a–c
will reduce the basicity of the nitrogen atom by effective de-
localization of nitrogen lone pair, this will increase the polar-
ization of the N–C bond and hence increase the rate of its
cleavage. The extent of this polarization of the N–C bond
should be similar in each substrate 6a–c. The reactivity order
of 90 and 45 of 6c over 6a and 6b, respectively, could be
explained in terms of the stabilization caused by the two
methyl groups in 6c on the six-membered transition state
proposed in the mechanistic pathway for these substrates.
Kinetic results and Arrhenius parameters are shown in
Table 3.
+
O
G
G
C
-1
k600 (s )
Z
G
Z
G
9.97 x 10-5
1.98 x 10-4
8.97 x 10-3
H
H
6a
6b
6c
H
Me
Me
Me
Scheme 7.
2-methyl-2-butanol 6c. Each of the 3-N,N-diphenylamino
alcohols 6a–c eliminates diphenylamine (Ph2NH together
with CH2O, CH3CHO, and acetone from 6a, 6b, and 6c,
Table 3. Rate coefficient (k, sꢀ1) and Arrhenius parameters of compounds (4–6)
Compound
T (K)
104 k (sꢀ1
)
log A (sꢀ1
)
Ea (kJ molꢀ1
)
K600K (sꢀ1
5.95ꢂ10ꢀ5
)
4a
615.05
634.05
653.05
671.65
691.45
749.55
0.960
1.956
3.681
4.534
8.900
35.71
4.690ꢁ0.18
102.45ꢁ2.37
4b
528.65
543.95
558.15
586.75
615.35
629.55
2.270
3.838
5.714
10.63
25.50
38.30
3.818ꢁ0.25
75.556ꢁ2.74
1.74ꢂ10ꢀ3
4c
5a
5b
456.55
473.45
482.05
409.55
507.85
0.853
2.650
3.801
4.969
13.33
7.552ꢁ0.43
3.884ꢁ0.13
1.267ꢁ0.071
101.65ꢁ3.93
82.333ꢁ1.63
48.232ꢁ0.80
5.06ꢂ10ꢀ2
5.22ꢂ10ꢀ4
1.17ꢂ10ꢀ3
609.25
637.75
652.05
666.35
680.75
6.560
14.19
19.96
26.78
36.53
519.65
544.25
570.15
595.95
621.65
647.35
2.710
4.335
6.814
10.76
16.28
24.58
5c
6a
456.55
473.45
482.05
499.05
507.85
0.787
2.065
3.801
4.906
12.44
7.589ꢁ0.44
7.797ꢁ0.34
102.11ꢁ0.98
135.55ꢁ4.25
5.02ꢂ10ꢀ2
9.97ꢂ10ꢀ5
611.95
624.75
650.55
663.45
676.35
689.15
1.572
3.183
7.945
14.81
20.78
32.20
6b
6c
608.25
622.65
651.65
680.05
708.75
2.465
4.531
9.930
20.87
46.54
5.167ꢁ0.23
2.830ꢁ0.34
101.91ꢁ2.92
56.035ꢁ0.32
1.98ꢂ10ꢀ4
8.97ꢂ10ꢀ3
472.05
484.75
489.15
510.15
522.45
4.555
5.853
8.570
12.56
17.54

M. R. Ibrahim et al. / Tetrahedron 63 (2007) 4768–4772
4771
3. Experimental
room temperature portionwise with stirring (0.5 g,
15 mmol). The reaction mixture was then stirred at room
temperature for 1 h and the solvent was removed in vacuo.
The product was extracted with ether (3ꢂ50 mL), washed
with water, and dried over anhydrous sodium sulfate. The
solvent was then removed in vacuo and the remaining prod-
uct was purified by silica gel column chromatography.
3.1. General
All melting points are uncorrected. 1H and 13C NMR spectra
were recorded on a Bruker DPX 400 MHz super-conducting
NMR spectrometer. Mass spectra were measured on VG
Autospec-Q (high resolution, high performance, tri-sector
GC/MS/MS) and with LCMS using Agilent 1100 series
LC/MSD with an API-ES/APCI ionization mode. Micro-
analysis was performed on a LECO CHNS-932 Elemental
Analyzer. The starting compounds 4a–c, 5a,b, and 6a were
prepared by modifications of reported procedures.
3.2.1. 4-Anilino-2-butanol 4b. Prepared from 4-anilino-2-
butanone,8 colorless oil, yield 1.4 g (85%), purified using
ethyl acetate–hexane as an eluent [Rf¼0.4, EtOAc–hexane
(1:4)] and recrystallized from hexane as colorless crystals,
mp 62–63 ꢃC (lit.9a 60–62 ꢃC). MS: m/z¼165 (M+, 90%),
1
93 (30%); H NMR (CDCl3): d 1.26 (d, 3H, J 6.2, CH3),
3.1.1. 3-Anilino-1-propanol 4a.6,7 A mixture of aniline
(5.4 mL, 5.5 mmol) and 3-chloro-1-propanol (1.74 mL,
1.8 mmol) was heated at 95–105 ꢃC for 5 h. After cooling,
the product was extracted with ether (50 mL), washed with
aqueous sodium hydroxide (20 mL, 1 N), and dried over an-
hydrous sodium sulfate. After removal of the solvent, the
product was obtained by vacuum distillation under reduced
pressure, bp 128–132 ꢃC, 0.5 mm (lit.7 bp 140 ꢃC, 0.5 mm)
as greenish yellow oil, yield 1.9 g (72%). MS: m/z¼151
1.78 (m, 2H, CH2COH), 2.19 (br, 2H, NH, OH), 3.29 (m,
2H, N–CH2), 4.00 (m, 1H, CH–O), 6.70 (d, 2H, J 7.9),
6.79 (t, 1H, J 7.8), 7.24 (t, 2H, J 7.8). 13C NMR (CDCl3):
d 24.0 (CH3), 38.1 (CH2), 39.9 (CH2), 67.3 (CH–OH),
113.5 (2CH), 119.8 (CH), 129.4 (2CH), 148.5 (C).
3.2.2. 4-N-Methylanilino-2-butanol 5b.9b,12 Prepared from
4-N-methylanilino-2-butanone,12 colorless oil, yield 1.4 g
(77%), purified using CHCl3–pet. ether 60–80 as an eluent
[Rf¼0.74, CHCl3–pet. ether 60–80 (1:2)]. 1H NMR
(CDCl3): d 1.27 (d, 3H, J 6.2, CH3), 1.73 (m, 2H, CH2),
2.36 (br, 1H, OH), 2.95 (s, 3H, NCH3), 3.47 (m, 2H, CH2),
3.94 (m, 1H), 6.78 (t, 1H, J 7.2), 6.83 (d, 2H, J 8.0), 7.28
(t, 2H, J 8.0). 13C NMR (CDCl3): d 24.3 (CH3), 35.9
(CH3), 38.9 (CH2), 51.1 (CH2), 67.2 (COH), 113.6 (2CH),
117.4 (CH), 129.5 (2CH), 150.1 (C).
1
(M+, 80%). H NMR (CDCl3): d 1.86 (quint, 2H, J 6.1,
CH2), 3.26 (t, 2H, J 6.1, CH2N), 3.53 (br, 2H, NH, OH),
3.76 (t, 2H, J 6.1, CH2O), 6.69 (d, 2H, J 8.0), 6.75 (t, 1H, J
8.1), 7.24 (t, 2H, J 7.6). Anal. Calcd for C9H13NO (151.2):
C 71.49; H 8.67; N 9.26. Found: C 71.24; H 8.72; N 9.44.
3.1.2. 3-N-Methylanilino-1-propanol 5a.
A mixture
of 3-chloro-1-propanol (6.8 g, 77 mmol), freshly distilled
N-methylaniline (7.7 g, 77 mmol), KI (0.35 g, 2.15 mmol),
K2CO3 (10 g, 77 mmol), and butanol (40 mL) was heated un-
der reflux for 4 days under nitrogen. After cooling and filtra-
tion of the suspended salts, the solvent was removed invacuo.
The remaining yellow oil was purified by vacuum distilla-
tion, bp 170–175 ꢃC, 0.5 mm (lit.7 160 ꢃC, 0.5 mm), yield
3.2.3. 4-N,N-Diphenylamino-2-butanol 6b. Prepared from
4-N,N-diphenylamino-2-butanone,15 dark yellow oil, yield
1.0 g (71%), purified using ethyl acetate–hexane as an eluent
[Rf¼0.44, EtOAc–hexane (1:4)]. MS: m/z¼241 (M+, 30%),
1
182 (100%), 168 (15%). H NMR (CDCl3): d 1.25 (d, 3H,
J 6.2, CH3), 1.79 (m, 3H, CH2–, OH), 3.89 (m, 3H, NCH2,
CHO), 6.99 (t, 2H, J 7.6), 7.06 (d, 4H, J 7.6), 7.31 (t, 4H,
J 7.6). 13C NMR (CDCl3): d 24.3 (CH3), 36.6 (CH2), 49.4
(CH2), 66.5 (C), 121.2 (4CH), 121.5 (2CH), 129.5 (4CH),
148.2 (2C). Anal. Calcd for C16H19NO (241.3): C 79.63;
H 7.94; N 5.80. Found: C 79.54; H 7.72; N 5.64.
1
7 g (53%). MS: m/z¼165 (M+, 80%). H NMR (CDCl3):
d 1.86 (quint, 2H, J 6.2), 1.90 (br, 1H, OH), 2.96 (s, 3H,
NCH3), 3.49 (t, 2H, J 6.2), 3.77 (t, 2H, J 6.2), 6.76 (t, 1H, J
7.2), 6.81 (d, 2H, J 7.9), 7.27 (t, 2H, J 6.9).10,11 13C NMR
(CDCl3): d 29.6 (CH3), 38.5 (CH2), 50.0 (CH2), 60.7
(CH2), 112.9 (2CH), 116.9 (CH), 129.3 (2CH), 149.7 (C).
3.3. Synthesis of 4-anilino-2-butanols 4c, 5c, and 6c:
general procedure
3.1.3. 3-N,N-Diphenylamino-1-propanol 6a. A mixture of
diphenylamine (1.69 g, 1.0 mmol), 3-iodo-1-propanol
(1.86 g, 1.0 mmol), anhydrous K2CO3 (0.2 gm), and tetra-
butylammonium bromide (0.2 g) was placed in the micro-
wave oven (Panasonic, Model Dimension, 4, NN-C 200S),
and irradiated with power at high temperature for 3 min.
The product was then extracted with ethyl acetate (10 mL)
and purified with silica gel column chromatography using
ethyl acetate–hexane solvent mixture, Rf¼0.73 (EtOAc–
hexane, 1:9), dark yellow oil, yield 0.6 g (26%).13,14 MS:
m/z¼227 (M+, 20%). 1H NMR (CDCl3): d 1.5 (br, 1H, OH),
1.94 (quint, 2H, J 6.3), 3.46 (t, 2H, J 6.3), 3.86 (t, 2H, J 6.2),
6.95 (t, 2H, J 7.8), 7.04 (d, 4H, J 8.0), 7.27 (t, 4H, J 8.0).
To a solution of MeMgI (freshly prepared from 1.0 g Mg and
2.5 mL MeI in 40 mL dry ether) was added the appropriate
4-anilino-2-butanone (10 mmol) at room temperature por-
tionwise with stirring under a nitrogen atmosphere. The re-
action mixture was heated under reflux for 24 h. After
cooling to room temperature, the mixture was quenched
with saturated aqueous ammonium chloride solution, the
ethereal layer was separated, and the aqueous layer was fur-
ther extracted with ether (3ꢂ50 mL). The combined ethereal
extract was dried over anhydrous sodium sulfate. The sol-
vent was then removed in vacuo and the remaining product
was purified by silica gel column chromatography.
3.2. Synthesis of 4-anilino-2-butanols 4b, 5b, and 6b:
general procedure
3.3.1. 4-Anilino-2-methyl-2-butanol 4c. Prepared from 4-
anilino-2-butanone,8 colorless oil, yield 1.0 g (60%), purified
using ethyl acetate–pet. ether 60–80 as an eluent [Rf ¼0.4,
EtOAc–pet.ether60–80(1:9)]andrecrystallizedfromhexane
To a solution of the appropriate 4-anilino-2-butanone
(10 mmol) in methanol (50 mL) was added NaBH4 at

4772
M. R. Ibrahim et al. / Tetrahedron 63 (2007) 4768–4772
to give colorless crystals, mp 58–60 ꢃC (lit.10 58–60 ꢃC).
MS: m/z¼179 (M+, 20%), 106 (100%), 77 (20%). 1H
NMR (CDCl3): d 1.33 (s, 6H, 2CH3), 1.84 (t, 2H, J 6.8),
2.68–2.92 (br, 2H, NH, OH), 3.32 (t, 2H, J 6.8), 6.68 (d,
2H, J 8.0), 6.76 (t, 1H, J 7.2), 7.21 (t, 2H, J 7.2).9a,10
13C NMR (CDCl3): d 30.0 (2CH3), 39.9 (CH2), 42.2
(CH2), 71.3 (COH), 113.6 (2CH), 118.2 (CH), 129.6 (2CH),
148.5 (C).
collected in a U-shaped trap cooled in liquid nitrogen. The
whole system was maintained at a pressure of 10ꢀ2 Torr
by an Edwards Model E2M5 high capacity rotary oil pump,
the pressure being measured by a Pirani gauge situated be-
tween the cold trap and the pump. Under these conditions
the contact time in the hot zone was estimated to be
y10 ms. The different zones of the products collected in
1
the U-shaped trap were analyzed by H NMR, LCMS, and
GC–MS. Relative and percent yields were determined
3.3.2. 4-N-Methylanilino-2-methyl-2-butanol 5c. Pre-
pared from 4-N-methylanilino-2-butanone,12 brown oil,
yield 1.5 g (77%),13 purified using CHCl3–pet. ether 60–80
as an eluent [Rf¼0.44, CHCl3–pet. ether 60–80 (3:7)]. MS:
from 1H NMR.4,5
References and notes
1
m/z¼193 (M+, 90%). H NMR (CDCl3): d 1.31 (s, 6H,
2CH3), 1.77 (t, 2H, J 7.7, CH2), 2.16 (br, 1H, OH), 2.94 (s,
3H, NCH3), 3.49 (t, 2H, J 7.7, CH2), 6.77 (t, 1H, J 7.2),
6.82 (d, 2H, J 8.0), 7.28 (t, 2H, J 8.0). 13C NMR (CDCl3):
d 29.9 (2CH3), 38.8 (CH2), 38.9 (CH2), 49.3 (NCH3), 70.8
(C–OH), 113.7 (2CH), 117.4 (CH), 129.5 (2CH), 149.9
(C). Anal. Calcd for C12H19NO (193.3): C 74.57; H 9.91;
N 7.25. Found: C 74.44; H 9.72; N 7.14.
1. Al-Awadi, S. A.; Abdallah, M. R.; Hassan, M. A.; Al-Awadi,
N. A. Tetrahedron 2004, 60, 3045–3049.
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3.3.3. 4-N,N-Diphenylamino-2-methyl-2-butanol 6c. Pre-
pared from 4-N,N-diphenylamino-2-butanone,15 brown oil,
yield 1.5 g (58%), purified using ethyl acetate–pet. ether
60–80 as an eluent [Rf¼0.4, EtOAc–pet. ether 60–80
(1:4)]. MS: m/z¼255 (M+, 60%), 182 (100%), 168 (20%).
1H NMR (CDCl3): d 1.31 (s, 6H, 2CH3), 1.56 (br, 1H,
OH), 1.89 (t, 2H, J 7.2, CH2), 3.91 (t, 2H, J 7.2, CH2),
6.98 (t, 2H, J 7.2), 7.05 (d, 4H, J 7.2), 7.30 (t, 4H, J 7.2).
13C NMR (CDCl3): d 29.7 (2CH3), 40.1 (CH2), 48.1 (CH2),
70.5 (C–OH), 121.1 (4CH), 121.4 (2CH), 129.5 (4CH),
148.0 (2C). Anal. Calcd for C17H21NO (255.3): C 79.96;
H 8.29; N 5.49. Found: C 79.84; H 8.12; N 5.44.
3.4. Kinetic runs and data analysis
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Procedures for the kinetic measurements have been detailed
in our earlier paper.1–4
3.5. General procedure for product analysis
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€
The sample was volatilized from a tube in a Buchi Kugelrohr
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oven through a 30ꢂ2.5 cm horizontal fused quartz tube.
This was heated externally by a Carbolite Eurotherm tube
furnace MTF-12/38A to a temperature of 600 ꢃC, the tem-
perature being monitored by a Pt/Pt-13%Rh thermocouple
situated at the center of the furnace. The products were