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1.
Dr. Dorian S. N. Parker Prof. Dr. Ralf. I. Kaiser Dr. Oleg Kostko Dr. Musahid Ahmed 《Chemphyschem》2015,16(10):2091-2093
The combustion of fossil fuels forms polycyclic aromatic hydrocarbons (PAHs) composed of five‐ and six‐ membered aromatic rings, such as indene (C9H8), which are carcinogenic, mutagenic, and deleterious to the environment. Indene, the simplest PAH with single five‐ and six‐membered rings, has been predicted theoretically to be formed through the reaction of benzyl radicals with acetylene. Benzyl radicals are found in significant concentrations in combustion flames, owing to their highly stable aromatic and resonantly stabilized free‐radical character. We provide compelling experimental evidence that indene is synthesized through the reaction of the benzyl radical (C7H7) with acetylene (C2H2) under combustion‐like conditions at 600 K. The mechanism involves an initial addition step followed by cyclization and aromatization through atomic hydrogen loss. This reaction was found to form the indene isomer exclusively, which, in conjunction with the high concentrations of benzyl and acetylene in combustion environments, indicates that this pathway is the predominant route to synthesize the prototypical five‐ and six‐membered PAH. 相似文献
2.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(5):1284-1288
The hitherto elusive disilavinylidene (H2SiSi) molecule, which is in equilibrium with the mono‐bridged (Si(H)SiH) and di‐bridged (Si(H2)Si) isomers, was initially formed in the gas‐phase reaction of ground‐state atomic silicon (Si) with silane (SiH4) under single‐collision conditions in crossed molecular beam experiments. Combined with state‐of‐the‐art electronic structure and statistical calculations, the reaction was found to involve an initial formation of a van der Waals complex in the entrance channel, a submerged barrier to insertion, intersystem crossing (ISC) from the triplet to the singlet manifold, and hydrogen migrations. These studies provide a rare glimpse of silicon chemistry on the molecular level and shed light on the remarkable non‐adiabatic reaction dynamics of silicon, which are quite distinct from those of isovalent carbon systems, providing important insight that reveals an exotic silicon chemistry to form disilavinylidene. 相似文献
3.
Shokyoku Kanaoka Nobuyuki Ikeda Akira Tanaka Hitoshi Yamaoka Toshinobu Higashimura 《Journal of polymer science. Part A, Polymer chemistry》2002,40(14):2449-2457
Random copolymers with high molecular weights of indene and p‐methylstyrene (pMeSt) were synthesized by cationic polymerization with trichloroacetic acid/tin tetrachloride in CH2Cl2 at low temperatures. When indene and pMeSt (1:1 v/v), for example, were polymerized at ?40 °C, both monomers were consumed at very similar rates to give a copolymer with high molecular weight [number‐average molecular weight (Mn): 8–9 × 104]. This is indeed quite unexpected behavior for the combination of these two monomers because pMeSt polymerized over 1000 times faster than indene in the homopolymerization under the reaction conditions previously described. The product copolymer of indene and pMeSt had a random monomer sequence in it that was confirmed by NMR analyses and thermal‐property measurements. In sharp contrast with pMeSt, styrene and p‐chlorostyrene, which have no electron‐donating groups on the phenyl ring, led to low molecular weight polymers (Mn < 10,000) in the copolymerization with indene (1:1 v/v). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2449–2457, 2002 相似文献
4.
Yuki Mizukami Dr. Haijun Li Prof. Dr. Kiyohiko Nakajima Dr. Zhiyi Song Prof. Dr. Tamotsu Takahashi 《Angewandte Chemie (International ed. in English)》2014,53(34):8899-8903
Titanacyclopentadienes, prepared from [Cp2TiBu2] and either two equivalents of an alkyne or a diyne, were treated with PMe3 (3 equiv) at 50 °C for 3 h and then with azobenzene at room temperature for 12 h to give 4,5,6‐trisubstituted indene derivatives with the loss of one substituent in good yields. This reaction contrasts sharply with our previously reported reaction for the formation of 4,5,6,7‐tetrasubstituted indene derivatives without the loss of substituents by the treatment of titanacyclopentadienes with azobenzene without PMe3. 13C NMR spectroscopy of the product derived from a 13C‐enriched complex revealed that the five carbon atoms originating from a Cp ligand were arranged linearly in the trisubstituted indene derivatives, in contrast to the 4,5,6,7‐tetrasubsituted indene derivatives, in which the corresponding five carbon atoms are arranged in a ring. 相似文献
5.
Dr. Yunxi Yao Prof. Konstantinos P. Giapis 《Angewandte Chemie (International ed. in English)》2016,55(38):11595-11599
Most Eley–Rideal abstraction reactions involve an energetic gas‐phase atom reacting directly with a surface adsorbate to form a molecular product. Molecular projectiles are generally less reactive, may dissociate upon collision with the surface, and thus more difficult to prove that they can participate intact in abstraction reactions. Here we provide experimental evidence for direct reactions occurring between molecular N2+ and O2+ projectiles and surface‐adsorbed D atoms in two steps: first, the two atoms of the diatomic molecule undergo consecutive collisions with a metal surface atom without bond rupture; and second, the rebounding molecule abstracts a surface D atom to form N2D and O2D intermediates, respectively, detected as ions. The kinematics of the collisional interaction confirms product formation by an Eley–Rideal reaction mechanism and accounts for inelastic energy losses commensurate with surface re‐ionization. Such energetic hydrogenation of dinitrogen may provide facile activation of its triple bond as a first step towards bond cleavage. 相似文献
6.
On Rearrangements by Cyclialkylations of Arylpentanols to 2,3‐Dihydro‐1 H ‐indene Derivatives. Part 3. The Acid‐Catalyzed Cyclialkylation of 3,4‐Dimethyl‐ and 3‐([ 2 H 3 ]Methyl)‐4‐methyl‐3‐phenylpentan‐2‐ol The cyclialkylation of 2‐([2H3]methyl)‐4‐methyl‐4‐phenyl[1,1,1‐2H3]pentan‐3‐ol ( 4 ) yielded a 1 : 1 mixture of 1,1‐di([2H3]methyl)‐2,3‐dimethyl‐1H‐indene ( 5 ) and of 2,3‐dihydro‐2,3‐di([2H3]methyl)‐1,1‐dimethyl‐1H‐indene ( 6 ) (Scheme 1) [1]. However, it was not clear whether the transposition takes place through the successive migration of a Ph, a Me and again the Ph group (Scheme 2, Path A: shift IV → VII → VIIa ) or through Ph‐, Me‐, and then i‐Pr‐group (Scheme 2, Path B: IV → VII → VIIb ). The cyclialkylation of 3‐([2H3]methyl)‐4‐methyl‐3‐phenylpentan‐2‐ol ( 7 ) yielded only one product, the 2,3‐dihydro‐2‐([2H3]methyl)‐1,1,3‐trimethyl‐1H‐indene ( 8 ), in accordance with the migrations according to Path A. This result is also a support for the total mechanism proposed for the cyclialkylation of 4 (Scheme 2). The transition of a tertiary to a secondary carbenium ion is not definitely ensured (see [1]). 相似文献
7.
Matthias Zeller Virginia B. Pett LeRoy W. Haynes 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(6):o343-o346
The reaction of 2‐chloro‐5‐nitropyridine with two equivalents of base produces the title carbanion as an intermediate in a ring‐opening/ring‐closing reaction. The crystal structures of the tetra‐n‐butylammonium salts of the intermediates, C16H36N+·C5H3N2O3−, revealed that pseudo‐cis and pseudo‐trans isomers are possible. One crystal structure displayed a mixture of the two isomers with approximately 90% pseudo‐cis geometry and confirms the structure predicted by the SN(ANRORC) mechanism. The pseudo‐cis intermediate undergoes a slow isomerization over a period of months to the pseudo‐trans isomer, which does not have the appropriate geometry for the subsequent ring‐closing reaction. The structure of the pure pseudo‐trans isomer is also reported. In both isomers, the negative charge is highly delocalized, but relatively small differences in C—C bond distances indicate a system of conjugated double bonds with the nitro group bearing the negative charge. The packing of the two unit cells is very similar and largely determined by the interactions between the planar carbanion and the bulky tetrahedral cation. 相似文献
8.
G. Raju V. Ramesh R. Srinivas G. V. M. Sharma B. Shoban Babu 《Journal of mass spectrometry : JMS》2010,45(6):651-663
Two new series of Boc‐N‐α,δ‐/δ,α‐ and β,δ‐/δ,β‐hybrid peptides containing repeats of L ‐Ala‐δ5‐Caa/δ5‐Caa‐L ‐Ala and β3‐Caa‐δ5‐Caa/δ5‐Caa‐β3‐Caa (L ‐Ala = L ‐alanine, Caa = C‐linked carbo amino acid derived from D ‐xylose) have been differentiated by both positive and negative ion electrospray ionization (ESI) ion trap tandem mass spectrometry (MS/MS). MSn spectra of protonated isomeric peptides produce characteristic fragmentation involving the peptide backbone, the Boc‐group, and the side chain. The dipeptide positional isomers are differentiated by the collision‐induced dissociation (CID) of the protonated peptides. The loss of 2‐methylprop‐1‐ene is more pronounced for Boc‐NH‐L ‐Ala‐δ‐Caa‐OCH3 (1), whereas it is totally absent for its positional isomer Boc‐NH‐δ‐Caa‐L ‐Ala‐OCH3 (7), instead it shows significant loss of t‐butanol. On the other hand, second isomeric pair shows significant loss of t‐butanol and loss of acetone for Boc‐NH‐δ‐Caa‐β‐Caa‐OCH3 (18), whereas these are insignificant for its positional isomer Boc‐NH‐β‐Caa‐δ‐Caa‐OCH3 (13). The tetra‐ and hexapeptide positional isomers also show significant differences in MS2 and MS3 CID spectra. It is observed that ‘b’ ions are abundant when oxazolone structures are formed through five‐membered cyclic transition state and cyclization process for larger ‘b’ ions led to its insignificant abundance. However, b1+ ion is formed in case of δ,α‐dipeptide that may have a six‐membered substituted piperidone ion structure. Furthermore, ESI negative ion MS/MS has also been found to be useful for differentiating these isomeric peptide acids. Thus, the results of MS/MS of pairs of di‐, tetra‐, and hexapeptide positional isomers provide peptide sequencing information and distinguish the positional isomers. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
9.
A number of researchers have indicated that a direct reaction of acetylene with oxygen needs to be included in detailed reaction mechanisms in order to model observed flame speeds and induction times. Four pathways for the initiation of acetylene oxidation to chain propagation are considered and the rate constants are compared with values used in the mechanisms:
- 1 3O2 + HCCH to triplet adduct and reaction on the triplet surface
- 2 3O2 + HCCH to triplet adduct, conversion of triplet adduct to singlet adduct via collision in the reaction environment, with further reaction of the singlet adduct
- 3 1O2 + HCCH to singlet adduct
- 4 Isomerization of HCCH to vinylidene and then vinylidene insertion reaction with 3O2
10.
Vladislav S. Krasnoukhov Prof. Dr. Valeriy N. Azyazov Prof. Dr. Alexander M. Mebel Dr. Srinivas Doddipatla Dr. Zhenghai Yang Shane Goettl Prof. Dr. Ralf I. Kaiser 《Chemphyschem》2021,22(14):1497-1504
The chemical dynamics of the elementary reaction of ground state atomic silicon (Si; 3P) with germane (GeH4; X1A1) were unraveled in the gas phase under single collision condition at a collision energy of 11.8±0.3 kJ mol−1 exploiting the crossed molecular beams technique contemplated with electronic structure calculations. The reaction follows indirect scattering dynamics and is initiated through an initial barrierless insertion of the silicon atom into one of the four chemically equivalent germanium-hydrogen bonds forming a triplet collision complex (HSiGeH3; 3 i1 ). This intermediate underwent facile intersystem crossing (ISC) to the singlet surface (HSiGeH3; 1 i1 ). The latter isomerized via at least three hydrogen atom migrations involving exotic, hydrogen bridged reaction intermediates eventually leading to the H3SiGeH isomer i5 . This intermediate could undergo unimolecular decomposition yielding the dibridged butterfly-structured isomer 1 p1 (Si(μ-H2)Ge) plus molecular hydrogen through a tight exit transition state. Alternatively, up to two subsequent hydrogen shifts to i6 and i7 , followed by fragmentation of each of these intermediates, could also form 1 p1 (Si(μ-H2)Ge) along with molecular hydrogen. The overall non-adiabatic reaction dynamics provide evidence on the existence of exotic dinuclear hydrides of main group XIV elements, whose carbon analog structures do not exist. 相似文献
11.
Daisuke Hashizume Naoki Takashima Takashi Oikawa Hideki Ishii Haruki Niwa Fujiko Iwasaki 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):827-829
The title compounds, 3a,9a‐trans‐9,9a‐trans‐4,4‐dimethyl‐9‐phenyl‐2,3,3a,4,9,9a‐hexahydrobenzo[f]indene, C21H24, (I), and 3a,4‐trans‐3a,9a‐cis‐9,9a‐trans‐4‐methoxy‐9‐phenyl‐2,3,3a,4,9,9a‐hexahydrobenzo[f]indene, C20H22O, (II), are products of the photoinduced electron‐transfer reaction of 1,1‐diphenyl‐1,n‐alkadienes. The molecular structures are in good agreement with those proposed from the reaction mechanisms. The central rings of the fused systems of both compounds take chair and boat conformations in (I) and (II), respectively. There are no remarkable short contacts shorter than the sum of the van der Waals radii in the crystals, but some weak C—H?π interactions are found. 相似文献
12.
Timothy G. Heath John Allison J Throck Watson 《Journal of the American Society for Mass Spectrometry》1991,2(4):270-277
The ion/molecule reaction of the tolyl cation with dimethyl ether has been investigated using triple quadrupole mass spectrometry. Three isomers with [C7H7]+ composition, the 3-tolyl, benzyl, and tropylium cations, were individually selected and reacted with dimethyl ether at a pressure of 1 mtorr in the second quadrupole (Q2) collision cell. Only the tolyl ion reacted to yield a methoxylated product ion peak at m/z 122. This reaction product having m/z 122 is postulated to be identical in structure with the molecular ion of 3-methyl anisole, as supported by thermochemical data and the similarity of the collision induced dissociation (CID) daughter ion mass spectra of the product ion and the molecular ion of authentic 3-methyl anisole. The daughter ion mass spectra of the three [C7H7]+ isomers during CID, by using a triple quadrupole mass spectrometer, are nearly identical; on the other hand, the analytical approach based on the ion/molecule reaction with dimethyl ether clearly exhibits distinct gas-phase chemistry reflecting structural differences among the isomers. Sot 相似文献
13.
Adrian K. Y. Lam Richard A. J. O'Hair 《Rapid communications in mass spectrometry : RCM》2010,24(12):1779-1790
A combination of electrospray ionisation (ESI), multistage and high‐resolution mass spectrometry experiments is used to examine the gas‐phase fragmentation reactions of the three isomeric phenylalanine derivatives, α‐phenylalanine, β2‐phenylalanine and β3‐phenylalanine. Under collision‐induced dissociation (CID) conditions, each of the protonated phenylalanine isomers fragmented differently, allowing for differentiation. For example, protonated β3‐phenylalanine fragments almost exclusively via the loss of NH3, only β2‐phenylalanine via the loss of H2O, while α‐ and β2‐phenylalanine fragment mainly via the combined losses of H2O + CO. Density functional theory (DFT) calculations were performed to examine the competition between NH3 loss and the combined losses of H2O and CO for each of the protonated phenylalanine isomers. Three potential NH3 loss pathways were studied: (i) an aryl‐assisted neighbouring group; (ii) 1,2 hydride migration; and (iii) neighbouring group participation by the carboxyl group. Finally, we have shown that isomer differentiation is also possible when CID is performed on the protonated methyl ester and methyl amide derivatives of α‐, β2‐ and β3‐phenylalanines. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
14.
The three‐component reaction of thiazole (benzothiazole), dialkyl but‐2‐ynedioate, and isatinylidene malononitriles in toluene at 110–120°C in a sealed tube afforded a mixture of cis/trans‐isomers of functionalized diastereoisomeric spiro[indoline‐3,7′‐thiazolo[3,2‐a]pyridines] and spiro[benzo[4,5]thiazolo[3,2‐a]pyridine‐3,3′‐indolines] in good yields. Both cis‐isomers and trans‐isomers were successfully separated out and fully characterized with spectroscopy and single crystal determination. Under similar conditions, the three‐component reaction containing 2‐(1,3‐dioxo‐1H‐inden‐2(3H)‐ylidene)malononitrile resulted in spiro[indene‐2,7′‐thiazolo[3,2‐a]pyridine] derivatives. 相似文献
15.
Structural Isomerization of the Gas‐Phase 2‐Norbornyl Cation Revealed with Infrared Spectroscopy and Computational Chemistry 下载免费PDF全文
Jonathan D. Mosley Dr. Justin W. Young Dr. Jay Agarwal Prof. Henry F. Schaefer III Prof. Paul v. R. Schleyer Prof. Michael A. Duncan 《Angewandte Chemie (International ed. in English)》2014,53(23):5888-5891
In an attempt to produce the 2‐norbornyl cation (2NB+) in the gas phase, protonation of norbornene was accomplished in a pulsed discharge ion source coupled with a supersonic molecular beam. The C7H11+ cation was size‐selected in a time‐of‐flight mass spectrometer and investigated with infrared laser photodissociation spectroscopy using the method of “tagging” with argon. The resulting vibrational spectrum, containing sharp bands in the C? H stretching and fingerprint regions, was compared to that predicted by computational chemistry. However, the measured spectrum did not match that of 2NB+, prompting a detailed computational study of other possible isomers of C7H11+. This study finds five isomers more stable than 2NB+. The spectrum obtained corresponds to the 1,3‐dimethylcyclopentenyl cation, the global minimum‐energy structure for C7H11+, which is produced through an unanticipated ring‐opening rearrangement path. 相似文献
16.
We have used model tripeptides GXW (with X being one of the amino acid residues glycine (G), alanine (A), leucine (L), phenylalanine (F), glutamic acid (E), histidine (H), lysine (K), or arginine (R)) to study the effects of the basicity of the amino acid residue on the radical migrations and dissociations of odd‐electron molecular peptide radical cations M.+ in the gas phase. Low‐energy collision‐induced dissociation (CID) experiments revealed that the interconvertibility of the isomers [G.XW]+ (radical centered on the N‐terminal α‐carbon atom) and [GXW].+ (radical centered on the π system of the indolyl ring) generally increased upon increasing the proton affinity of residue X. When X was arginine, the most basic amino acid, the two isomers were fully interconvertible and produced almost identical CID spectra despite the different locations of their initial radical sites. The presence of the very basic arginine residue allowed radical migrations to proceed readily among the [G.RW]+ and [GRW].+ isomers prior to their dissociations. Density functional theory calculations revealed that the energy barriers for isomerizations among the α‐carbon‐centered radical [G.RW]+, the π‐centered radical [GRW].+, and the β‐carbon‐centered radical [GRWβ.]+ (ca. 32–36 kcal mol−1) were comparable with those for their dissociations (ca. 32–34 kcal mol−1). The arginine residue in these GRW radical cations tightly sequesters the proton, thereby resulting in minimal changes in the chemical environment during the radical migrations, in contrast to the situation for the analogous GGW system, in which the proton is inefficiently stabilized during the course of radical migration. 相似文献
17.
Andrey I. Poddel'sky Yury A. Kurskii Alexandr V. Piskunov Nikolay V. Somov Vladimir K. Cherkasov Gleb A. Abakumov 《应用有机金属化学》2011,25(3):180-189
New triphenylantimony(V) o‐amidophenolates (AP‐Me,Et)SbPh3 (1) and (AP‐Me,iPr)SbPh3 (2) with unsymmetrically substituted N‐aryl groups and (AP‐Et,Et)SbPh3 (3) with symmetrical N‐aryl group {AP‐R1,R2 is 4,6‐di‐tert‐butyl‐N‐[2‐alkyl(R1),6‐alkyl(R2)‐phenyl]‐o‐amidophenolate dianion} were synthesized and characterized in detail. Complexes were examined for dioxygen activity. The unsymmetrical complexes 1 and 2 were found to form different geometrical isomers (A and B) of spiroendoperoxides [L‐R1,R2(O2)]SbPh3 (4 and 5, respectively) with different dispositions of peroxide group and N‐aryl fragment (methyl and peroxide group are on the same side of the molecule in the less shielded isomer A, and on different sides in the more hindered isomer B). The isomer A prevails over isomer B, reflecting the possibility of steric control on the dioxygen‐binding reaction. Complex 3, where R1 = R2 = Et, formed the isomers 6A and 6B as 50:50. The ratio 4A:4B was 60:40 (for methyl‐ethyl containing complex 4) and it increased up to 80:20 for methyl‐isopropyl‐containing 5. The molecular structure of isomers 4A and 4B was confirmed by X‐ray analysis. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
18.
Weizhi Geng Dr. Chao Wang Jie Guang Wei Hao Dr. Wen‐Xiong Zhang Prof. Dr. Zhenfeng Xi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(26):8657-8664
1,2,3,4‐Tetrasubstituted cyclopentadienes and indene derivatives with identical or different substituents were obtained in good to excellent isolated yields through a zirconocene‐ and CuCl‐mediated intermolecular coupling process. This synthetic procedure involved three organic partners, including one CH2I2, and two different or identical alkynes. Two alkynes or one diyne undergo Cp2ZrII‐mediated (Cp=η5‐C5H5) pair‐selective reductive coupling to afford the corresponding zirconacyclopentadiene derivatives, which react, in the presence of CuCl and 1,3‐dimethyl‐3,4,5,6‐tetrahydro‐2(1 H)‐pyrimidinone (DMPU), with CH2I2 through intermolecular followed by intramolecular coupling to afford the cyclopentadiene derivatives. An application of the prepared tetrasubstituted cyclopentadiene derivatives was demonstrated by the facile synthesis of the corresponding zirconocene complexes [(4RCp)2ZrCl2] and [(4RCp)2ZrR′2] (R′=Me, Et, or nBu). The unique 1,2,3,4‐tetrasubstituted cyclopentadiene ligands and the corresponding metallocenes are expected to have further applications in organometallic chemistry and organic synthesis. 相似文献
19.
Bernd Wrackmeyer Khadija Shahid Rhett Kempe Christian Döring Wolfgang Milius 《应用有机金属化学》2010,24(5):398-401
The reaction of 1‐trimethylsilyl‐indazole with boranes affords indazaboles accompanied by elimination of trimethysilane. Thus, the two isomers of parent indazabole are formed in a 1:1 ratio using borane in THF (BH3/THF), characterized by NMR spectroscopy in solution (1H, 11B and 13C NMR). In contrast, the analogous reaction with 1,2‐bis(tetramethylene)diborane(6) proceeds to give a single isomer of the B‐alkylated indazabole via symmetric ring cleavage of the diborane(6), as shown by NMR in solution and X‐ray structural analysis in the solid state. The molecular structure is fluxional in solution. In the solid state, the central B2N4 ring adopts a distorted boat conformation. Calculated gas phase geometries of the parent indazaboles and of the B‐alkylated indazabole were optimized by DFT methods at the B3LYP/6‐311 + G(d,p) level of theory. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
20.
Ying Liu Jiuming He Ruiping Zhang Jiangong Shi Zeper Abliz 《Journal of mass spectrometry : JMS》2009,44(8):1182-1187
The fragmentation behavior of hydroquinone glycosides involving one or two sugar groups from Fraxinus sieboldiana and their analogue arbutin was investigated systematically by electrospray ionization tandem mass spectrometry in negative ion mode. The characteristic fragmentation reaction of these compounds was through the homolytic and heterolytic cleavage of the O‐glycosidic bond to produce radical aglycone ion ([Y0 ? H]??) and aglycone ion (Y0?), respectively. Unambiguous differentiation between the mono‐O‐glycoside isomers which differ in glycosylation position was achieved by comparing the relative abundance of [Y0 ? H]?? and Y0? ions with the optimized collision energy. In the fragmentation of 1, 4‐di‐O‐glycosides, only the Y0? ion was produced when the first glucosyl residue was expelled. However, both the [Y0 ? H]?? and Y0? ions were present when the second glucosyl residue was eliminated. In addition, an interesting [Y0‐2H]? ion was present in the product ion spectra of hydroquinone glycosides with methoxy group(s) substituted at C‐3 or/and C‐5 positions of the benzene ring. The results of this study can facilitate the rapid determination of hydroquinone glycosides in crude plant extracts and also reveal that the systematic investigation and optimization of collision energy play an important role in the differentiation of isomers which have subtle differences in structures. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献