- Email: [email protected]
The reaction of 3,3-dimethyl-1,2-dioxetane with sodium azide
Tetrahedron Letters N0.10, Pp. 749-751,1971. Pergamon Press.
Printed in Great Britain.
TRE REACTION OF 3,3-DIMEYHYL-1,2-DIOEEIAEE WITB SODIUM ASIDE' W. H. Richardson and V. F. Iiodge Department of Chemistry, San Mego State College San Mego, California 92115 (Received in USA 26 January 1971; received in UK for publication 16 February 1971)
Previously we had demonstrated the presence of 3,3-dimethyl-1,2-dioxetene
(la, Rl = Rp =
CR39 R3 = Rq = A) as an intermediate in the basic decomposition of chloro-t_butyl hydroperoxide (cBIIp)2 and reported the reactions of a few nucleophiles with &.2c include the more nucleophilic
azide ion, which is of particular interest, since sn intermediate
produced in the reaction of olefins with photochemically be trapped by azide ion.3 (1) or a perepoxide
This study is extended to
generated singlet oxygen is reported to
It wss suggested3y4 that the intermediate wes either a 1,2-dioxetene
end that reaction with azide ion gave a g-szido hydroperoxide
(9
(3).
CI
Q-9 I
1
A\
R1R2C - CR~RI,
RlRzC -
CR~RI,
F”” RlR2C - F3R4 R3
1
-2
3
Additional evidence has been presented for 'hc Teneration of 1,24ioxetanes singlet oxygen with olefins.5
from the reaction of
Our results with -la indicate that azide ion attacks the 1,2-diOXe-
tane to give acetone end nitrogen, but that the B-azido hydroperotide
(s,
R1 = Rp = CH3, R3 =
R4 = H) is either not produced or if formed, it is a transient intermediate. During the decomposition of CBRP (initial concentration, 0.013
749
E) with base (0.200 Msodium
750
No.10
hydroxide)in 60% aqueousmethanol at 30.0', the iodometrictiter decreasedat approximatelythe ssme rate in the absence (1.36 x 10q3 set-I, u = 1.58 l$ or the presence of 1.00 g sodium aside (1.2 x 10-3 set-1, IJ= 1.2 M). Similarly,the rate coefficientfor decay of light emission, which wss shown to equal the iodometricrate coefficient,2b was approximatelyequal in the absence (2.19 x 10m3 set-1, lJ= 1.58 I$ or presence (1.99 x 10s3 see-I.,u = 1.58 @
of 0.182 g
sodium aside at 30' with en initial CBHP concentrationof 1.00 x 10e2 E and a base concentration of 1.58 &
Product studies,with reactant concentrations the same ss in the former reaction,
indicatea 6s yield of acetone (by glc) and 35% yield (by vacuum line, mess spectralanalysis) of nitrogenbased on the hydroperoxide. Controlexperimentswith t_butyl hydroperoxide,bese and aside ion give no reaction. This indicatesthat the potentialintermediateB-szidohydroperoxide (3a) &es not build up in concentrationunder the basic reaction conditions. Furthermore, significantconcentrationsof_?_aare not formed in the absence of strong base. When an isolatedsample of -la2c (0.2 M) is treated with sodium aside (0.5 @
in aqueous solution,an
immediateevolutionof nitrogen results and acetone is the only observableproduct in the nmr spectrumafter nitrogen evolutionis complete. A potassiumiodide-starchtest at this time indicatesthe absence of peroxides. 2bsC it is found that aside ion does increasethe By a previouslyreportedkinetic analysis, rate disappearanceof the 1,2-dioxetane &. _&in
The rate coefficient(kfobs)for disappearanceof
the absence of sodium aside is 9.00 x low3 set-l at 30' in 60% aqueousmethanol ([CBHp],=
1.00 x 10m2 M, [Base]= 1.58 g), while in the presence of 0.182 Msodium aside kfobs increases to 23.6 x lo-3 set-l. It wes shown2c that kfobs = kf + kfB[OH-] + kfd[X]; where kf. kfB and kfd are the unimolecular,base catalyeedand added reactantrate coefficientsfor the decomposition of -la. In this instance,kfd I kfB _ end it is calculatedto be 80.3 x 10m3 Ilmol-'set-'. 3
Mechanismscan be written where azide ion attacks either oxygen or carbon of -la to eventually give acetone and nitrogen. The claim that B-asidohydroperoxidesare isolable,3would suggest that attack by aside ion on&occurs
at oxygen, since attack at carbon would give -3a. However,
analysisof the above kinetic data with the aid of the Edwards Equation6suggeststhat attack at carbon is most likely and that -3a is a transientintermediate. It was demonstratedpreviously2= that attack by bromide ion on.& occurredat wgen, at 30° in 60% aqueousmethanol ([=I0 ad*
iOn
ah0
attacksaat
where kfd : kfBr- = 18.7 X 10m3 kmOl_' see-l
= 1.00 x 10m2 M, [Base]= 1.58 M, [Br-1 = 1.00 &I.
owgen, one calculates7the ratio kf _/kfBr- to be 3.4 x N3
10-5.
If
751
No.10
Instead,the observedratio is 4.29 (= 80.2 x 10-3/x3.7x 10-3), which differs significantlyin magnitude as well as being reversed in or&r comparedto the calculatedvalue and suggests displacementat carbon. A reasonablemechanism for the &composition of -la in the presence of azide ion, which explainsthe products and is initiatedby attack at carbon is given below.
o-o I
I
(m3)*c - cH2 -
kf
CH3coCR3+ CH20 + hv
-la
oo-
kfar -la + N3- 3.
(CH3)&N3
(a3)2c
A-
/ \
I
CR2-N 'N25
(CH3)2C CO-7 CH2-N- + N2.
5-
I120 A_-
CH3COCH3
+
CIi2
=
BOH + OH-
References 1.
This work was supportedby the PetroleumResearchFund, administeredby the American Chemical society.
2.
5531 (1966) ; (a) W. H. Richardson,J. W. Peters, and W. P. Konopka, Tetrahedronw., (b) W. H. Richardsonand V. F. Hodge, ibid., 2271 (1970); (c) W. H. Richardsonand V. F. Hodge, J. Amer. Chem. &.,93, xxxx (1971).
3. W. Fenical,D. R. Kearns, and P. Radlick,4. Amer. Chem. *,l, 4. See also: A. G. Schultz and R. H. Schlessinger,Tetrahedronw.,
7771 (1969). 2731 (1970).
5.
(a) W. H. Richardsonand V. F. Hodge, e. a. Chem.,s 1216 (1970); (b) P. D. Bartlett and (c) S. Mazur and C. S. Foote, ibid.,% A. P. Schaap, E. Amer. Chem. &.,, 92, 3223 (lm; 3275 (1970).
6.
J. 0. Edwards,s.,
7.
with a = 6.31, -/kfBr_ = a’% _- EnBr_) + e(HN3--HBIsi,, B3 3 E,Br- = 1.51, HN3- = 6.46 and %r- = -6.00.6~8
*,
1540 (1954).
Loaf
6 = -.394,
GN_=
1.58,
3
8. The values of a and B correspondto the reactionof nucleophileswith hydrogen peroxide ("Rate Law I").9 9.
J. 0. Edwards,J. Phys. Chem.,, 56 279 (1952). 3
Printed in Great Britain.
TRE REACTION OF 3,3-DIMEYHYL-1,2-DIOEEIAEE WITB SODIUM ASIDE' W. H. Richardson and V. F. Iiodge Department of Chemistry, San Mego State College San Mego, California 92115 (Received in USA 26 January 1971; received in UK for publication 16 February 1971)
Previously we had demonstrated the presence of 3,3-dimethyl-1,2-dioxetene
(la, Rl = Rp =
CR39 R3 = Rq = A) as an intermediate in the basic decomposition of chloro-t_butyl hydroperoxide (cBIIp)2 and reported the reactions of a few nucleophiles with &.2c include the more nucleophilic
azide ion, which is of particular interest, since sn intermediate
produced in the reaction of olefins with photochemically be trapped by azide ion.3 (1) or a perepoxide
This study is extended to
generated singlet oxygen is reported to
It wss suggested3y4 that the intermediate wes either a 1,2-dioxetene
end that reaction with azide ion gave a g-szido hydroperoxide
(9
(3).
CI
Q-9 I
1
A\
R1R2C - CR~RI,
RlRzC -
CR~RI,
F”” RlR2C - F3R4 R3
1
-2
3
Additional evidence has been presented for 'hc Teneration of 1,24ioxetanes singlet oxygen with olefins.5
from the reaction of
Our results with -la indicate that azide ion attacks the 1,2-diOXe-
tane to give acetone end nitrogen, but that the B-azido hydroperotide
(s,
R1 = Rp = CH3, R3 =
R4 = H) is either not produced or if formed, it is a transient intermediate. During the decomposition of CBRP (initial concentration, 0.013
749
E) with base (0.200 Msodium
750
No.10
hydroxide)in 60% aqueousmethanol at 30.0', the iodometrictiter decreasedat approximatelythe ssme rate in the absence (1.36 x 10q3 set-I, u = 1.58 l$ or the presence of 1.00 g sodium aside (1.2 x 10-3 set-1, IJ= 1.2 M). Similarly,the rate coefficientfor decay of light emission, which wss shown to equal the iodometricrate coefficient,2b was approximatelyequal in the absence (2.19 x 10m3 set-1, lJ= 1.58 I$ or presence (1.99 x 10s3 see-I.,u = 1.58 @
of 0.182 g
sodium aside at 30' with en initial CBHP concentrationof 1.00 x 10e2 E and a base concentration of 1.58 &
Product studies,with reactant concentrations the same ss in the former reaction,
indicatea 6s yield of acetone (by glc) and 35% yield (by vacuum line, mess spectralanalysis) of nitrogenbased on the hydroperoxide. Controlexperimentswith t_butyl hydroperoxide,bese and aside ion give no reaction. This indicatesthat the potentialintermediateB-szidohydroperoxide (3a) &es not build up in concentrationunder the basic reaction conditions. Furthermore, significantconcentrationsof_?_aare not formed in the absence of strong base. When an isolatedsample of -la2c (0.2 M) is treated with sodium aside (0.5 @
in aqueous solution,an
immediateevolutionof nitrogen results and acetone is the only observableproduct in the nmr spectrumafter nitrogen evolutionis complete. A potassiumiodide-starchtest at this time indicatesthe absence of peroxides. 2bsC it is found that aside ion does increasethe By a previouslyreportedkinetic analysis, rate disappearanceof the 1,2-dioxetane &. _&in
The rate coefficient(kfobs)for disappearanceof
the absence of sodium aside is 9.00 x low3 set-l at 30' in 60% aqueousmethanol ([CBHp],=
1.00 x 10m2 M, [Base]= 1.58 g), while in the presence of 0.182 Msodium aside kfobs increases to 23.6 x lo-3 set-l. It wes shown2c that kfobs = kf + kfB[OH-] + kfd[X]; where kf. kfB and kfd are the unimolecular,base catalyeedand added reactantrate coefficientsfor the decomposition of -la. In this instance,kfd I kfB _ end it is calculatedto be 80.3 x 10m3 Ilmol-'set-'. 3
Mechanismscan be written where azide ion attacks either oxygen or carbon of -la to eventually give acetone and nitrogen. The claim that B-asidohydroperoxidesare isolable,3would suggest that attack by aside ion on&occurs
at oxygen, since attack at carbon would give -3a. However,
analysisof the above kinetic data with the aid of the Edwards Equation6suggeststhat attack at carbon is most likely and that -3a is a transientintermediate. It was demonstratedpreviously2= that attack by bromide ion on.& occurredat wgen, at 30° in 60% aqueousmethanol ([=I0 ad*
iOn
ah0
attacksaat
where kfd : kfBr- = 18.7 X 10m3 kmOl_' see-l
= 1.00 x 10m2 M, [Base]= 1.58 M, [Br-1 = 1.00 &I.
owgen, one calculates7the ratio kf _/kfBr- to be 3.4 x N3
10-5.
If
751
No.10
Instead,the observedratio is 4.29 (= 80.2 x 10-3/x3.7x 10-3), which differs significantlyin magnitude as well as being reversed in or&r comparedto the calculatedvalue and suggests displacementat carbon. A reasonablemechanism for the &composition of -la in the presence of azide ion, which explainsthe products and is initiatedby attack at carbon is given below.
o-o I
I
(m3)*c - cH2 -
kf
CH3coCR3+ CH20 + hv
-la
oo-
kfar -la + N3- 3.
(CH3)&N3
(a3)2c
A-
/ \
I
CR2-N 'N25
(CH3)2C CO-7 CH2-N- + N2.
5-
I120 A_-
CH3COCH3
+
CIi2
=
BOH + OH-
References 1.
This work was supportedby the PetroleumResearchFund, administeredby the American Chemical society.
2.
5531 (1966) ; (a) W. H. Richardson,J. W. Peters, and W. P. Konopka, Tetrahedronw., (b) W. H. Richardsonand V. F. Hodge, ibid., 2271 (1970); (c) W. H. Richardsonand V. F. Hodge, J. Amer. Chem. &.,93, xxxx (1971).
3. W. Fenical,D. R. Kearns, and P. Radlick,4. Amer. Chem. *,l, 4. See also: A. G. Schultz and R. H. Schlessinger,Tetrahedronw.,
7771 (1969). 2731 (1970).
5.
(a) W. H. Richardsonand V. F. Hodge, e. a. Chem.,s 1216 (1970); (b) P. D. Bartlett and (c) S. Mazur and C. S. Foote, ibid.,% A. P. Schaap, E. Amer. Chem. &.,, 92, 3223 (lm; 3275 (1970).
6.
J. 0. Edwards,s.,
7.
with a = 6.31, -/kfBr_ = a’% _- EnBr_) + e(HN3--HBIsi,, B3 3 E,Br- = 1.51, HN3- = 6.46 and %r- = -6.00.6~8
*,
1540 (1954).
Loaf
6 = -.394,
GN_=
1.58,
3
8. The values of a and B correspondto the reactionof nucleophileswith hydrogen peroxide ("Rate Law I").9 9.
J. 0. Edwards,J. Phys. Chem.,, 56 279 (1952). 3