Unusual Acetonitrile Adduct Formed via Photolysis of 4′-Chloro-2-Hydroxybiphenyl in Aqueous Solution

Article abstract of DOI:10.1021/acs.joc.0c01115

In this work, 2,4′-dichlorobiphenyl (1) yielded 4′-chloro-2-hydroxybiphenyl (2) after photolysis in neutral acetonitrile aqueous (ACN-H2O) solutions. Ultrafast spectroscopic measurements and density functional theory (DFT) computations were performed for 2 in ACN and ACN-H2O (v/v, 1:1). These results were compared with previously published results for 2-hydroxybiphenyl (3). The counterparts 2 and 3 went through a singlet excited state intramolecular proton transfer (ESIPT) in ACN but behaved differently in ACN-H2O with a dehydrochlorination process occurring for 2 and an ESIPT taking place for 3. Computational results indicate that the phenol O-H bond elongates after photoexcitation to induce a concerted asynchronous process with the C-Cl bond increasing first followed by HCl elimination. A biradical intermediate (IM1) is then formed with some spin located at the phenyl 4′-C radical that appears to favor a hydrogen atom transfer (HAT) process and some spin located on phenoxyl that appears to prefer a subsequent a CH2CN radical rebound. The hydrogen bond promotes HCl elimination, while this is disfavored for ESIPT, making 4′-Cl extrusion the predominant process in ACN-H2O solutions. The mechanistic investigations have fundamental and significant implications for the understanding of polychlorinated biphenyl photolysis in an aqueous environment and hence the photodegradation of these kinds of pollutants in the natural environment.

Full text of DOI:10.1021/acs.joc.0c01115

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Article
Unusual Acetonitrile Adduct Formed via Photolysis of 4′-Chloro-2-
Hydroxybiphenyl in Aqueous Solution
Xiting Zhang, Yan Guo, Erin Dallin, Jiani Ma,* Mingdong Dai, and David Lee Phillips*
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ABSTRACT: In this work, 2,4′-dichlorobiphenyl (1) yielded 4′-chloro-2-hydroxybi-
phenyl (2) after photolysis in neutral acetonitrile aqueous (ACN−H2O) solutions.
Ultrafast spectroscopic measurements and density functional theory (DFT) computations
were performed for 2 in ACN and ACN−H2O (v/v, 1:1). These results were compared
with previously published results for 2-hydroxybiphenyl (3). The counterparts 2 and 3
went through a singlet excited state intramolecular proton transfer (ESIPT) in ACN but
behaved differently in ACN−H2O with a dehydrochlorination process occurring for 2 and
an ESIPT taking place for 3. Computational results indicate that the phenol O−H bond
elongates after photoexcitation to induce a concerted asynchronous process with the C−
Cl bond increasing first followed by HCl elimination. A biradical intermediate (IM1) is
then formed with some spin located at the phenyl 4′-C radical that appears to favor a
hydrogen atom transfer (HAT) process and some spin located on phenoxyl that appears
to prefer a subsequent •CH2CN radical rebound. The hydrogen bond promotes HCl
elimination, while this is disfavored for ESIPT, making 4′-Cl extrusion the predominant process in ACN−H2O solutions. The
mechanistic investigations have fundamental and significant implications for the understanding of polychlorinated biphenyl
photolysis in an aqueous environment and hence the photodegradation of these kinds of pollutants in the natural environment.
tional theory (DFT) calculations were all conducted to study
the photolysis of 2 in ACN and ACN−H2O, respectively.
These new results were then compared with previously
published results on the related analog 2-hydroxybiphenyl
(3). The main finding is that a dehydrochlorination
intermediate promotes a HAT process followed by a radical
rebound to accomplish the ACN adduct formation after
photolysis of 2 in the presence of water.
INTRODUCTION
■
Polychlorinated biphenyls (PCBs) are prevalent in the natural
environment. Due to their tendency to bioaccumulate and act
as a carcinogen,1 much research has been done on the PCBs’
photochemical fate in the environment and in laboratory
settings.2−5 The photolyzed PCBs may dechlorinate in the
presence of water, yielding less chlorinated congeners such as
chloro-hydroxybiphenyl.6,7 The PCB photoproducts are also
environmental contaminants themselves and this indicates the
necessity for investigating their photochemical behavior so as
to gain a more complete picture of the fate of the PCB class of
chemicals in the environment.
In particular, previous research has indicated that o-
phenylphenol is a chemical capable of cytotoxic effects to
living organisms.8 Dulin and co-workers6 reported that 2-
chlorobiphenyl yields an acetonitrile (ACN) adduct product 2-
acetamidebiphenyl via nucleophilic addition after being
photolyzed in neutral ACN aqueous (ACN−H2O) solutions.
A mechanistic investigation on the analog 4-chorobiphenyl
thus has new importance.
For simplicity, 2,4′-dichlorobiphenyl (1) was chosen as the
starting PCB in this contribution as its ortho-substitution has
been shown to increase its photoreactivity.2,9,10 Here, we
attempt to clarify how the acetonitrile adduct product is
formed via a photolysis of 4′-chloro-2-hydroxybiphenyl (2) in
the presence of water. Gas chromatography−mass spectrom-
etry (GC/MS), femtosecond transient absorption (fs-TA),
nanosecond transient absorption (ns-TA), and density func-
RESULTS AND DISCUSSION
■
GC/MS Results. Compound 2 (yield: ∼10%) and 2-
acetamide-4′-chlorobiphenyl (4, yield: ∼90%) were produced
after photolysis of 1 in ACN−H2O as determined by GC/MS
(Scheme 1, eq 1). The ortho-Cl is, respectively, substituted by
an OH group and acetamide group, which is consistent with
the case for 2-chlorobiphenyl (5) (Scheme 1, eq 2) reported
by Dulin and co-workers.6 The 4-Cl seems less reactive than 2-
Cl so that the para dechlorinated product is not detected for 1
(Scheme 1, eq 1) and 2-methoxy-4′-chlorobiphenyl (7)
(Scheme 1, eq 3) in ACN−H2O.
Received: May 8, 2020
Published: August 26, 2020
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fs-TA and ns-TA Study of 2. fs-TA and ns-TA
experiments were first conducted for 2 in ACN and these
results were found to be similar to those for 3 in ACN.13 The
first species has a strong absorption at 415 nm with a tail from
550 to 700 nm (Figure 2a) is assigned to 12 (left superscript 1
Scheme 1. Reactions Discussed in the Present Article
On the above basis, we examined the photochemical
activities of the photolysis product of 2, another 4-Cl
compound which is expected to behave similar to 3. Previous
studies reported an excited state intramolecular proton transfer
(ESIPT) reaction (Scheme 1, eq 4) for the photolysis of 3 in
ACN as well as in ACN−H2O solutions.11,12 Steady-state
photolysis experiments were performed for 2 in ACN−H2O
(v/v, 1:1). Unexpectedly, there were two main kinds of
photoproducts, 3 and the ACN adduct product 9 (Scheme 1,
eq 5), which involves a para dechlorination, and the latter was
determined to be the primary photoproduct using the GC/MS
test (see Figure 1). For the ortho compounds 1 and 5 in
Figure 2. fs-TA and ns-TA obtained for 2 in ACN under the
excitation of 266 nm and TD-M062X/6-311g**/SMD (ACN) results
with a scale factor of 1.2 (left superscript numbers 0, 1, and 3 indicate
the ground state, lowest singlet excited state, and triplet state,
respectively).
indicates the lowest singlet excited state), which then converts
to a new species that has shoulder bands at 363 and 395 nm
(see Figure 2b) and decays from 2.4 to 200 ns (see Figure 2c).
With the help of time-dependent (TD-DFT) calculations
(Figure 2d) this new species can be attributed to a singlet
1
ESIPT product (also denoted as 8 though it has the 4′-Cl
group) formed from a phenol proton transfer to an adjacent
aromatic ortho-C atom. The similar time-resolved spectro-
scopic results for 2 in MeOH (Figures 2S−5S) suggested that
ESIPT is also the predominant process in this H-bonding
solvent.
The fs-TA and ns-TA data for 2 in neutral ACN−H2O (v/v,
1:1) solutions (Figure 3) are significantly different from those
observed in ACN for 2 and that in ACN−H2O (v/v, 1:1) for 3
(see published results11−13). Accompanying the generation of
12 (at 415 nm), a new species with a broad absorption in the
region of 450−700 nm was observed (Figure 3a). This new
Figure 1. (A) Decomposition of 2 and growth of (B) 9 and (C) 3
after the photolysis of 2 in ACN−H2O (v/v, 1:1) as measured by
GC/MS.
ACN−H2O solutions, ACN adducts were also the primary
photoproducts. These unexpected results indicate that even
though H2O is a better nucleophile, ACN is added
preferentially in these systems.
It should be noted that the dechlorination and ACN adduct
processes display significant differences between 2-Cl and 4-Cl,
in which the 2-Cl system is substituted by OH or the
acetamide group, while in the 4-Cl system the Cl is replaced by
either a H atom or ACN is not added on the para-C atom.
Nucleophilic addition is proposed as the dechlorination
process for the ortho-substitution.6 However, the above
experimental observations suggest that there might be some
other reaction pathway responsible for the ACN adduct after
photolysis of 2.
Figure 3. fs-TA and ns-TA spectra of 2 in ACN−H2O (v/v, 1:1)
under the excitation of 266 nm and TD-M062X/6-311g**/SMD
(ACN) results with a scale factor of 1.2 (left superscript numbers 1
and 2, respectively, mean an open-shell singlet state and radical).
B
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Figure 4. Potential energy surface profiles of 2 in ACN and ACN−H2O solution were mapped employing (TD)M062X/6-311G**/SMD(ACN)
calculations. Paths x, y, z, m, and n on the right superscript represent ESIPT, HCl elimination, ESPT, HAT, and ACN adducts, respectively.
1
signal is tentatively assigned to be the solvated electrons based
8.9 kcal/mol higher in energy than TSx (Figure 4iia). TD-
DFT calculations were performed for 2 with 1H2O and 2H2O
added explicitly to the reaction system, respectively (Figure
4iib,c) and ESIPT is still more favored than the dechlorination
with energy gap differences of 3.9 and 3.1 kcal/mol for 1H2O
and 2H2O cases, respectively. However, when 6H2O was
added explicitly in the reaction system, dechlorination
becomes the preferential process with a 3.7 kcal/mol lower
in energy barrier than ESIPT (see Figure 4iid).
on similarity to some literature results.14 Both 2 and the
1
solvated electrons decayed after 1.0 ps and a new transient
intermediate (denoted as IM1) appeared at 370 and 555 nm,
which was observable during the time region of 18.2 ps to 2.5
ns (Figure 3b). The ns-TA for 2 detected IM1 (370 and 555
nm) mixed with a new transient intermediate species (denoted
as IM2) with absorption features at 360 and 610 nm (Figure
3c). The absorption bands for IM1 were quenched from 18.2
ps to 50 ns. IM2 is a relatively long-lived species (at least 200
ns). Since PCBs tend to dechlorinate IM1 after photo-
excitation, the experimental spectra of IM1 and IM2 were,
respectively, compared with the simulated electronic absorp-
tion spectra of several probable intermediates related with the
dechlorination process. It was found that IM1 exhibited a
reasonable similarity with the calculated ultraviolet−visible
(UV−vis) spectrum of 1IM1 or 3IM1 (left superscript 3
indicates the triplet state, Figures 3d and 8S). 1IM1 was
located using a broken symmetry methodology but not via the
The potential energy surface profile for 2 with 6H2O (see
1
Figure 4iii) shows that an S1 surface starting from 2 goes
through 1TSy with an activation energy of 9.6 kcal/mol.
Photoexcitation occurs mainly on the aromatic π electrons of
12 (see Figure 5), which should have little effect on the in-
1
3
TD-DFT method. IM1 and IM1 have a biradical character
formed via a HCl elimination process. This attribution is in
agreement with the fact that the absorption bands at 370 and
555 ns were quenched when oxygen is present in the solution.
The IM2 signal at 50 ns is similar to that in the calculated
Figure 5. Angle between the C−Cl bond and the adjacent phenyl ring
and the spin distribution for 2 and TSy with 6H2O. (Unit: °).
1
1
2
UV−vis spectrum (see Figure 3d) for IM2 (left superscript 2
plane C−Cl σ bond. However, the angle between the C−Cl
bond and the adjacent phenyl ring decreased from 180° in 2
1
indicates radical species), which has a phenoxy radical
1
to 146° in 1TSy (see Figure 5), and the excited π electrons can
gain a conjugation interaction with the C−Cl σ bond to
facilitate the Cl anion extrusion. The charge is transferred from
the electron-donor phenol to the electron-acceptor chlor-
ophenyl, which is favored for the deprotonation and the system
then dechlorinates,15−17 and this can be further promoted by
the intermolecular H-bonding between the phenol O−H bond
and the H2O molecules. The triplet species 32 is not
considered because of the big energy gap (20.0 kcal/mol)
with 12 makes the intersystem crossing (ISC) less efficient than
the singlet excited state dechlorination process. The IRC
calculation reveals that 1TSy will go forward to a conical point
(denoted as CP) between the S1 and S0 surfaces before it
character and can be produced by a HAT to IM1. This
assignment is consistent with the experimental result that IM2
is not affected by the presence or absence of oxygen in the
solution.
DFT Study of 2. To investigate the mechanism in detail,
the potential energy surface profiles of 2 in ACN (Figure 4i)
were studied. The electronic transition from 02 (left superscript
0 means the ground state S0) to 12 was induced upon
1
irradiation (Figure 4a). 2 overcomes an energy barrier of 2.4
kcal/mol and then the transition state 1TSx (right superscript x
1
means ESIPT) goes downhill to 8 by an exothermic process
(12.6 kcal/mol). 18 is a long-lived species (at least 200 ns) and
decays by the internal conversion (IC) to a highly vibrational
state of 08, which is unstable and soon goes through 0TSx via a
barrierless pathway to the starting material 02 (Figure 6S).The
1
reaches the dehydrochlorination intermediate IM1. This CP
can be located using the broken symmetry methodology, which
3
0
photochemical process induced by 2 seems difficult because
is an open-shell singlet TS. This CP can go backward to 2
(⟨S2⟩ = 0 as seen in the IRC calculation results), while it will
go forward to the dehydrochlorination intermediate 1IM1
(⟨S2⟩ = 1.0387 as seen in the IRC calculation results). This can
of the fast singlet ESIPT process.
The dechlorination process on the S1 surface in ACN can be
ruled out as 1TSy (right superscript y means dechlorination) is
C
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be supported by the fact as shown in Figure 3b and 4iii that 12
radical rebound. The •CH2CN radical combined with the 5-C
atom produces the ground state intermediate 0IM3, which then
will go through a TS with an activation energy of 14.0 kcal/mol
and an exothermic process of 22.8 kcal/mol to form the ACN
adduct 9 (Figure 4v). That is, it is not a nucleophilic addition
but is a dehydrochlorination intermediate promoted HAT
followed by a radical rebound for the inert ACN to be added
onto 2 (Scheme 2).
1
1
decays much faster than IM1 formation, intimating that 2
went through the CP and then mainly went back to the
0
1
starting material 2, while only a little amount produces IM1.
After 3TSy, the triplet surface also goes close to the CP so that
3IM1 is mixed with IM1 (Figures 7S and 8S) and IM1 is
1
1
employed to do the DFT calculations in consideration of the
1
subsequent radical rebound. IM1 has a biradical character
1
1
The O−H and C−Cl bond distances for 2 and TSy with
ACN, 1H2O, 2H2O, and 6H2O are listed in Figure 6. The O−
H bond is elongated from 0.97 to 1.06 Å, while the C−Cl bond
with one phenoxyl α spin and one phenyl β radical (see
Scheme 2).
1
changed little at 1.74−1.75 Å for 2 as the number of H2O
Scheme 2. Proposed ACN Adduct Formation Mechanism of
a
increased, corresponding to the H-bonding between the
phenol O−H bond and H2O increasing with the number of
water molecules in the system and ESIPT requires extra energy
to break the strong H-bonding in ACN−H2O so that the
ESIPT energy barrier for 2 in 6H2O (14.2 kcal/mol) is much
higher than that in ACN (2.4 kcal/mol, Figure 4ii); and
therefore opens a door for the dehydrochlorination in ACN−
H2O. Furthermore, the elongated phenol O−H bond
promotes charge transfer and earns power to favor the
2 in ACN−H2O Solution
1
following Cl extrusion via the π−σ conjugation in TSy with
6H2O (see Figure 5), decreasing the dehydrochlorination
energy barrier for 2 (9.5 kcal/mol) (Figure 4ii). This is
1
supported by the fact that TSy just has the Cl extrusion
character since the phenol O−H bond changed little compared
1
to that on 2 (see Figure 6). Intrinsic reaction coordinate
(IRC) calculations revealed that both O−H and C−Cl bonds
1
are elongated after TSy in the 6H2O case. Therefore, the
phenol O−H bond elongated by H-bonding after photo-
excitation induces a concerted asynchronous HCl elimination.
ESIPT is not considered for methoxy-substituted biphenyl
(7). The dechlorination energy barrier for 7 in ACN−H2O
should be similar to that (∼11.3 kcal/mol) for 2 in ACN (see
Figure 4iia). However, 7 is found to be photostable (Scheme 1,
eq 5), intimating that HCl elimination is decisive for 4′-Cl
extrusion, which is significantly different from the 2-Cl cleavage
(Scheme 1, eqs 1 and 2). The dehydrochlorination linked
together by a water bridge occurs by a proton transfer from the
proton-donating phenol OH group to water. Methanol can
also serve as the solvent bridge for the proton transfer, while
no MeOH adducts were detected in neat MeOH even in
MeOH−H2O (v/v, 4:1) (Figure 1S-4S). Agmon et al.18
pointed out that the number of hydrogen bonds, both made
and broken, facilitate the proton transfer as well as dielectric
stabilization of the anion. The fact that water can donate two
hydrogen bonds and methanol only one is critical, in that
methanol must break its lone hydrogen bond in order to form
a
The spin population for key intermediates 1IM1 and 2IM2 are
indicated (isovalue: 0.014).
1IM1 performs as the precursor for the following reaction.
The phenyl 4′-C radical is reactive for HAT from ACN, a
better H-donor with a lower energy barrier of 9.6 kcal/mol
leading to a larger exothermic process of 23.0 kcal/mol than
the case for H2O (Figure 4iv). Then, 2IM2 is formed with one
spin mainly delocalized to the phenoxy O and 5-C atoms (see
Scheme 2). It should be noted that 2IM2 also might be
produced by an excited state proton transfer (ESPT) from a
phenol proton to the 4′-C atom accompanied with the Cl atom
extrusion, while this possibility is ruled out because it has a
higher energy barrier of 18.8 kcal/mol compared to that of the
HAT pathway (Figure 4iid, TSz). The phenoxy O and 5-C
atoms are two possible active sites for the following •CH2CN
1
1
1
Figure 6. Phenol O−H and C−Cl bond distances of 2 and TSy with ACN, 1H2O, 2H2O, and 6H2O (unit: Å).
D
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The ACN adduct 9, a pale yellow oil, was isolated from the
photolysis mixture of 2 by PTLC (silica gel, 1:2 ethyl acetate/hexane)
a new one. This distinction is subtle but has an important
impact on the kinetics, which was further supported by the
high-level calculations by Hynes et al. to predict the trajectory
of proton transfer and the role of solvent reorganization in the
reaction coordinate.19 Therefore, the proton transfer occurs
with a bigger methanol cluster and increases the entropic
requirements (not the enthalpic effect) for the proton transfer
compared to the water solvent.20 Then, less energy is required
to break the H-bonding between MeOH and phenol OH and
the ESIPT energy barrier is still lower than the dehydro-
chlorination for 2. ESIPT then is still favored over the
dehydrochlorination and no HCl elimination occurred and no
MeOH adducts were observed though MeOH is a better H-
donor than ACN.
1
and characterized by MS, HRMS, H NMR, 13C{1H} NMR, long-
1
range heteronuclear correlation (HETCOR), and COSY. H NMR
(400 MHz, CDCl3/TMS) δ (ppm): 3.71 (s, 2H), 5.42 (s, 1H), 6.95−
7.02 (m, 1H), 7.17−7.23 (m, 2H), 7.41−7.53 (m, 5H). 13C{1H}
NMR (CDCl3) δ (ppm): 152.5 (C−OH), 118.0, 136.4 (11C), 116.8
(1C, ortho to CH2CN and the adjacent phenyl ring), 23.09
(−CH2−). Long-range HETCOR confirmed that the hydroxyl
group is para to the CH2CN group, with 1H COSY further confirming
that these substituents are on the same ring. MS 209 m/z (M+).
HRMS calcd for C14H11NO 209.0790, found 209.0796. HRMS calcd
for C14H10NO (M−H) 208.0757, found 208.0770. Other minor ACN
adducts were formed only in trace yields and could not be identified
with confidence.
The fs-TA experiments were done employing a commercial
regenerative amplified Ti/sapphire laser system and similarly, the
ns-TA experiments were done using a commercial laser flash
photolysis apparatus. The fs-TA experiments used 267 nm photolysis
and a white light continuum (330−800 nm) probe laser pulse while
the ns-TA experiments utilized 266 nm laser photoexcitation and a
xenon lamp for the probe light. An absorbance of unity at 266 nm was
used for the sample solutions in the fs-TA and ns-TA experiments.
More details of the fs-TA and ns-TA tests are described elsewhere.23
The DFT computations employed the (U)M062X/6-311G**/
SMD(ACN) level of theory to find the optimized geometries and
vibrational wavenumbers for the transients considered to be possible
intermediates for the reactions of interest in this study. All of the
calculations used the Gaussian 16 program suite.24 Further details of
the calculations are given in the Supporting Information.
CONCLUSIONS
■
In summary, the dehydrochlorination is decisive for para-Cl
dechlorination and the formation of subsequent ACN adducts
that is an interesting incorporation of the cosolvent ACN (this
is remarkably different from the reactions observed for ortho-Cl
biphenyls when H2O is present). This finding is important as it
increases the overall understanding of PCB photochemistry, as
the chloro-hyroxybiphenyls are an important photochemical
product of these PCBs, which also have associated environ-
mental concerns. By changing the substitution pattern of the
biphenyls, different patterns of reactivity are envisaged. These
results may open up another series of compounds that react via
dechlorination intermediates that are relevant in environmental
photochemistry and also promising in synthetic chemistry.
This preference for incorporation of the solvent (in this case
ACN) is due to the H-donor ability of these compounds.
Perhaps they will also react with other better H-donor organic
compounds in the aqueous environment and find a wider use
in chemistry.
ASSOCIATED CONTENT
■
sı
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.joc.0c01115.
fs-TA spectra of the reported species, optimized
geometries of the RC, TS, and PC, the reaction energy
profile obtained from the M062X/6-311G** calcula-
tions, and the excited state energies and oscillator
strengths from the TD-DFT (M062X/6-311G**)
calculations for the transient species along with the
Cartesian coordinates, Gibbs free energies, and the
thermal correction to the Gibbs free energy for the
optimized geometry from the M062X/6-311G** calcu-
lations for the compounds and intermediates (PDF)/.
EXPERIMENTAL AND COMPUTATIONAL
METHODS
■
Compounds 1 and 2 were synthesized by utilizing previously reported
methods detailed in the literature21,22 and the synthesis routes are
shown in Schemes 1S and 2S, respectively. For characterization of the
samples prepared, please see the NMR (1H, 13C) spectra displayed in
the Supporting Information.
All photolysis experiments were conducted in a Rayonet RPR 100
containing 16 lamps (350 nm). Cooling was achieved with an internal
cold finger. The sample solutions (3 × 10−3 M) were prepared in
ACN−H2O and purged with argon 15 min prior to irradiation.
Following photolysis, the solutions were extracted with CH2Cl2 and
dried over MgSO4. All photoproducts were isolated by preparative
thin-layer chromatography (PTLC) in ethyl acetate/hexane and
identified by NMR (1H, 13C) and MS.
Photoproduct 4′-chloro-2-hydroxybiphenyl (2), a pale yellow oil,
was isolated from the photolysis mixture of 1 in 1:1 ACN−H2O by
PTLC (silica gel, 1:5 ethyl acetate/hexane) and confirmed by MS
with M+ at 204, 1H NMR (400 MHz, CDCl3/TMS) δ (ppm): 5.27 (s,
1H), 6.97 (dd, J = 8.1, 1.0 Hz, 1H), 7.03 (td, J = 7.5, 1.1 Hz, 1H),
7.24−7.31 (m, 2H), 7.42−7.49 (m, 4H) and 13C{1H} NMR (100
MHz, CDCl3/TMS) δ (ppm): 116.2, 121.2, 127.2, 129.3, 129.5,
130.4, 130.6, 133.8, 135.8, 52.4.
AUTHOR INFORMATION
■
Corresponding Authors
Jiani Ma − Key Laboratory of Synthetic and Natural Functional
Molecule Chemistry of Ministry of Education, College of
Chemistry and Materials Science, Northwest University, Xi’an
710172, P. R. China; orcid.org/0000-0003-3325-0762;
Email: majiani@nwu.edu.cn
David Lee Phillips − Department of Chemistry, The University
of Hong Kong, Hong Kong 999077, P. R. China; orcid.org/
0000-0002-8606-8780; Email: phillips@hku.hk
Authors
Photoproduct 2-acetamide-4′chlorobiphenyl (4), a pale yellow
solid, was isolated from the photolysis mixture of 1 in 1:1 ACN−H2O
by PTLC (silica gel, 1:5 ethyl acetate/hexane) and confirmed by MS
Xiting Zhang − Key Laboratory of Synthetic and Natural
Functional Molecule Chemistry of Ministry of Education,
College of Chemistry and Materials Science, Northwest
University, Xi’an 710172, P. R. China; Department of
Chemistry, The University of Hong Kong, Hong Kong 999077,
P. R. China; orcid.org/0000-0001-7602-1965
1
with M+ at 245 and H NMR (400 MHz, CDCl3/TMS) δ (ppm):
2.03 (s, 3H), 7.05 (s, 1H), 7.20 (t, J = 7.2 Hz, 2H), 7.27−7.33 (m,
2H), 7.34−7.40 (m, 1H), 7.45 (d, J = 8.4 Hz, 2H), 8.16 (d, J = 8.2
Hz, 1H).
E
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to a Carbon Atom of an Aromatic Ring Observed for 2-Phenylphenol.
Yan Guo − Key Laboratory of Synthetic and Natural Functional
Molecule Chemistry of Ministry of Education, College of
Chemistry and Materials Science, Northwest University, Xi’an
710172, P. R. China
Erin Dallin − Department of Chemistry, University of Victoria,
Victoria, British Columbia V8W 2Y2, Canada
Mingdong Dai − Key Laboratory of Synthetic and Natural
Functional Molecule Chemistry of Ministry of Education,
College of Chemistry and Materials Science, Northwest
University, Xi’an 710172, P. R. China
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́
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Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.joc.0c01115
Author Contributions
X.Z. and Y.G. contributed equally. The manuscript was written
through contributions of all authors and all have given approval
to the final version of the manuscript.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
The research was sponsored in part by grants from the
National Natural Science Foundation of China (21973075) to
J.M. and the Research Grants Council of Hong Kong
(HKU17301815) to D.L.P. and partial support from the
Areas of Excellence Scheme (Grant AoE/P-03/08), the UGC
Special Equipment Grant (SEG-HKU-7), and the University of
Hong Kong Development Fund 2013-2014 project “New
Ultrafast Spectroscopy Experiments for Shared Facilities”. We
would like to thank Peter Wan for useful discussion of this
work.
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