首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Catalytic hydrogenation of 4-nitro-1,8-bis(dimethylamino)naphthalene afforded the previously unknown 1-amino-4,5-bis(dimethylamino)naphthalene, subsequent methylation of which gave 1-methylamino and 1-dimethylamino “proton sponge” derivatives. The pK a values of 1-amino-, 1-methylamino-, and 1-dimethylamino-4,5-bis(dimethylamino)-naphthalenes estimated by1H NMR in DMSO-d6 are equal to 9.8, 10.1, and 8.0, respectively.  相似文献   

2.
The reaction of 1,8-bis(dimethylamino)naphthalene (“proton sponge”) with trifluoroacetic anhydride afforded new derivatives of naphtho[1,8-c,d]pyran,viz., trans-) (4) andcis-1,3-dihydroxy-6,7-bis(dimethylamino)-1,3-bis(trifluoromethyl)-1H,3H-naphthol[1,8-c,d]pyran (5) and symmetrical 3,4,10,11-tetrakis(dimethylamino)-7,14-bis(trifluoromethyl)-7,14-epoxydinaphtho[1,8-a,b;1′, 8′-ef]cyclooctane (3), which belongs to a new type of double “proton sponges,” along with the expected 1,8-bis(dimethylamino)-4-trifluoroacetylnaphthalene. The structures of compounds3 and4 were established by spectral studies and X-ray diffraction analysis.  相似文献   

3.
First indirect evidence for the formation of a radical cation of 1,8-bis(dimethylamino)naphthalene (“proton sponge”) in reactions with HNO3, HNO2, NO2, and I2 has been obtained. In all cases, the products of reaction of the radical cation with nucleophiles and/or its dimer, 4,5,4′,5′-tetrakis(dimethylamino)-1,1′-binaphthyl, have been isolated. 4-Chloro-1,8-bis(dimethylamino)naphthalene has been regioselectively synthesized in high yield. For Part 24, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 320–324, February, 1998.  相似文献   

4.
From deuterium labelling experiments it was concluded that metastable molecular ions of ethyl methyl sulfide lose a methyl radical with the formation of both [CH3S?CH2]+ amd [CH3CH?SH]+˙ The fragmentation reactions of metastable ions generated with these structure are losses of C2H2, H2S and CH4. These reactoins and the preceding isomerizations have also been studied by means of deuterium labelling. From the results it is concluded that the three fragmentation reactions most probably occur from ions with a C? C? S skeleton. Appearance energy measurements for ions generated with the two structures above and all give rise to the same ΔHf value for these three isomeric forms. Ab initio molecular orbitals calculations confirm that these three ions fortuitously have very similar heats of formation. A potential energy diagram rationalizing the isomerizations and the principal fragmentation reaction is presented.  相似文献   

5.
The electron impact (EI) ionization-induced fragmentation pathways of the new 1,9-bis(dimethylamino) phenalenium cation [1]+ were investigated. The peri-dimethylamino substituents of [1]+ are incorporated in a trimethine cyanine substructure and show strong steric interactions. A mechanism is proposed for the unusual elimination of CH3N?CH2, HN(CH3)2 and (CH3)3N from [1]+ and for the accompanying cyclizations to heterocyclic ions: prior to fragmentation, the intact cation [1]+ rearranges, by reciprocal CH3 and H transfers, to new isomeric cations which decompose subsequently in a characteristic way. A wealth of consistent information on dissociation pathways and fragment structures is provided by collision-induced dissociation tandem mass spectra, collision-induced dissociation mass-analysed ion kinetic energy spectra and exact mass measurements of the salt cation and of its primary fragment ions. The liquid secondary ion mass spectrum of [1]+ is very similar to its EI mass spectrum.  相似文献   

6.
The behaviour under electron impact (70 eV) which includes some rearrangement processes of some tetraorganodiphosphanedisulfides R2P(S)-P(S)R2 (R ? CH3, C2H5, n-C3H7, n-C4H9, C3H5, C6H5) and CH3RP(S)–P(S)CH3R (R ? C2H5, n-C3H7, n-C4H9, C6H5, C6H5, C6H5,CH2) is reported and discussed. Fragmentation patterns which are consistent with direct analysis of daughter ions and defocusing metastable spectra are given. The atomic composition of many of the fragment ions was determined by precise mass measurements. In contrast to compounds R3P(S) loss of sulphur is not a common process here. The first step in the fragmentation of these compounds is cleavage of one P–C bond and loss of a substituent R?. The second step is elimination of RPS leading to [R2PS]+ from which the base peaks in nearly all the spectra arise. The phenyl substituted compounds give spectra with very abundant [(C6H5)3P]+. and [(C6H5)2CH3P]+. ions respectively, resulting from [M]+. by migration of C6H5. Rearrangement of [M]+. to a 4-membered P-S ring system prior to fragmentation is suggested.  相似文献   

7.
The 75 eV electron impact mass spectra of 1,1-bis(dimethoxyphenyl)methanes bearing o-methoxy groups are dominated by intense peaks corresponding, at least formally, to benzyl ions [(CH3O)2C6H3CH2]+ (b). They arise from ions [((CH3O)2C6H3)2CH]+ (a), which are in turn formed from molecular ions by loss of an alkyl radical through benzylic cleavage. The analysis of compounds labelled with 2H or 13C at methoxy groups led to the determination of the mechanism. Hydrogen migration, as hydride, followed by electrophilic substitution by the methylene carbon of the phenyl methylene ether cation through a six-centred transition state is responsible for the formation of benzylic ions b.  相似文献   

8.
Aminomethylation of 1,8-bis(dimethylamino)naphthalene (proton sponge) afforded a series of its 4-dialkylaminomethyl-substituted derivatives. An attempt to introduce the second peri-dialkylaminomethyl group unexpectedly led to the formation of salts with the 2,2-dialkyl-6,7-bis(dimethylamino)-2-azonia-2,3-dihydrophenalene cation. The structure of one of these salts was established by X-ray diffraction analysis. Treatment of 1,8-bis(dimethylamino)-4-piperidinomethylnaphthalene with iodomethane gave a spiro compound rather than the expected N-[4,5-bis(dimethylamino)-1-naphthylmethyl]-N-methylpiperidinium iodide. This spiro compound was generated through cyclodimerization of the 1-naphthylmethyl carbocations. These transformations provide evidence that proton sponge-derived Mannich bases quaternized at the dialkylaminomethyl group are unstable and undergo the spontaneous transformation into the resonance-stabilized 4,5-bis(dimethylamino)-1-naphthylmethyl carbocation. By contrast, 4-dialkylamino-1-dimethylaminomethylnaphthalenes gave methoiodides, which are stable under standard conditions. The latter compounds undergo the nucleophilic substitution of the NR3 group typical of such salts.  相似文献   

9.
The new compound C10H6P(S)[NSi(CH3)3]2P(S) ( 3 ) which contains a P2N2 heterocycle has been prepared in low yield by partial thermal decomposition of 1-{[N,N′-bis(trimethylsilyl)acetamidinium]sulfido}-3-(trimethylsilylamino)-1 H,3 H,1 λ5,3 λ5-naphtho[1,8 a,8-cd][1,2,6]thiadiphosphinine-1,3-dithione [CH3C{NHSi(CH3)3}2]+[C10H6P(S)(NHSiMe3)SP(S)2] ( 2 ). Reaction of 2 with potassium hydroxide in acetonitrile gives the completely desilylated product [CH3C(NH2)2]+[C10H6P(S)(NH2)SP(S)2] ( 4 ). The structures of the new compounds 3 and 4 were elucidated by FTIR and NMR spectroscopy methods and by X-ray structure analyses.  相似文献   

10.
The fragmentation of 2-azafluorene and its methyl and phenyl-substituted derivatives was studied. It is shown that ejection of an RCN fragment (R=CH3, C6H5) by the molecular ions leads to a more intense peak if R is in the 3 position of the azafluorene ring. It was established that, in contrast to the dissociative ionization of fluorene, all of the ions of which are formed from the (M-H)+ fragment, the fragmentation of 2-azafluorene and its derivative also takes place from the molecular ion. Randomization of the deuterium atoms attached to C9 with the remaining hydrogen atoms was observed.Translated from Khimiya Geterotisiklicheskikh Soedinenii, No. 1, pp. 101–105, January, 1977.  相似文献   

11.
The electron ionization fragmentation patterns of 5-methyl-3-(o-, m- and p-tolyl)-1,2,4-oxadiazoles (1a—c) have been examined by metastable ion and high resolution mass spectrometry. The o-tolyl isomer loses CO and C2H2O from the metastable molecular ion whereas the m- and p-tolyl isomers lose only CH3CN thus indicating a strong ortho effect in directing the fragmentation in 1a. Slight differences between o-, m- and p-tolyl isomers in the collisional activation fragmentation of stable [C7H6N]+ ions suggest that structural differences exist even after a series of extensive rearrangements of the molecular ions. Metastable ion kinetic energy (MIKE) and collisional activation (CA) spectra were very helpful in providing valuable information about many fragments.  相似文献   

12.
A detailed energy-resolved study of the fragmentation of CH2?CHCH(OH)CD2CD3 (1-d5) has been carried out using metastable ion studies and charge exchange techniques, combined with collision-induced dissociation studies to establish the structures of fragment ions. At low internal energies (metastable ions) the molecular ion of 1-d5 rearranges to the 3-pentanone structure and fragments by loss of C2H5 or C2D5 leading to the acyl structure, [CH3CH2C?O]+ or [CD3CD2C?O]+, for the fragment ion. However, with increasing internal energy of the molecular ion this rearrangement process decreases rapidly in importance and loss of C2D5 by direct cleavage, leading to [CH2?CHCH?OH]+, becomes the dominant fragmentation reaction. As a result the [C3H5O]+ ion seen in the electron impact mass spectrum of 1-penten-3-ol has predominantly the protonated acrolein structure.  相似文献   

13.
The 1-[1,8-bis(dimethylamino)-4-naphthyl[ethyl carbocation generated from the corresponding alcohol in benzene in the presence of Al2O3 undergoes elimination according to theE1 mechanism to give previously unknown 1,8-bis(dimethylami no)-4-vinyl naphthalene in a good yield. This compound was also synthesized from 1,8-bis(dimethylamino)-4-formylnaphthalene by the Wittig reaction. Polymerization of the vinylic derivative obtained was studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2297–2300, September, 1996.  相似文献   

14.
The 4-deuterio, 4-methyl, 4-iodo, 4-methylthio, 4-trimethylsilyl, and 4-ethoxycarbonyl derivatives of 1,8-bis(dimethylamino)naphthalene (proton sponge) and some related alcohols were prepared by the reactions of 4,5-bis(dimethylamino)-1-naphthyllithium or 4,5-bis(dimethylamino)-1-naphthylmagnesium bromide with the corresponding electrophilic reagents. New representatives of double proton sponges with the structures of 1,1"-binaphthyl ketone and 1,1"-binaphthylmethanol were synthesized. The pK a values of selected compounds in DMSO were measured by competitive protonation.  相似文献   

15.
The metastable ion supported fragmentation process in the mass spectra of the cyclohexadienyl derivative C6H7Mn(CO)3, the cycloheptadienyl derivative C7H9Mn(CO)3, the 1,2,3,4,5-and 1,2,3,5,6-pentahaptocyclootadienyl derivatives C8H11Mn(CO)3, the cyclooctatrienyl derivative C8H9Mn(CO)3 and the substituted cyclopentadienyl derivative (CH3)2NCH2C5H4Mn(CO)3, are described. Losses of carbonyl groups, generally stepwise, from the molecular ions to give the corresponding [M – 3CO]+· ions are first observed. Further fragmentation of the carbonyl-free [M – 3CO]+· ions can involve a variety of processes such as the following: (a) elimination of a neutral manganese atom to give a hydrocarbon fragment; (b) elimination of a neutral hydrocarbon fragment to give an [MnH]+· ion; (c) dehydrogenation; (d) elimination of a 2-carbon C2H2 or C2H4 fragment; (e) elimination of a C3H4 or C3H6 fragment as a neutral species when it is bridging two carbon atoms bonded to manganese, as in C8H9Mn(CO)3 and 1,2,3,4,5,h5-C8H11Mn(CO)3, respectively. Fragmentation of the [M – 3CO]+· ion in (CH3)2NCH2C5H4Mn(CO)3 presents the following additional features: (a) elimination of C6H6 with a nitrogen shift from carbon to manganese; (b) elimination of a neutral dimethylamino fragment to give [C6H6Mn]+·, which then loses neutral C6H6, C6H5 or Mn fragments and thus is formulated tentatively as [(fulvene)Mn]+· or [C6H5MnH]+· rather than [(benzene)Mn]+·.  相似文献   

16.
Ab initio molecular orbital calculations with large, polarization basis sets and incorporating valence electron correlation have been employed to examine the [C2H2O] potential energy surface. Four [C2H2O] isomers have been identified as potentially stable, observable ions. These are the experimentally well-known ketene radical cation, [CH2?C?O] (a), and the presently unknown ethynol radical cation, [CH2?C? OH] (b), the oxirene radical cation (c) and an ion resembling a complex of CO with [CH2], (d). The calculated energies of b, c and d relative to a are 189, 257 and 259 kJ mol?1, respectively. Dissociation of ions a and d is found to occur without reverse activation energy.  相似文献   

17.
Mass spectra of substituted benchrotrenyls RC6H5Cr(CO)3 where R?H, F, CI, I, CH3, OCH3, COOCH3, C2H5, N(CH3)2, NH2, C6H5, C(CH3)3, p-C6H4NH2, CH2C6H5, CH2CH2C6H5), 1,3,5-(CH3)3C6H3Cr(CO)3 and 1,2,3,5-(CH3)4C6H2Cr(CO)3 have been studied. It has been found that for monosubstituted benchrotrenyls there is a linear dependence of the parameter log [Cr]+/[RC6H5Cr]+) on the number of degrees of freedom of the [RC6H5Cr]+ ion. Decarbonylation of the molecular ions is not affected by the nature of the substituent R. The results are interpreted in terms of the quasi-equilibrium theory of mass spectra.  相似文献   

18.
The catalytic reduction of acetophenone, methyl α-acetamidocinnamate, and dimethyl itaconate with alcohol-modified sodium borohydride was studied in the presence of complexes CoCl2·L2 (L2 are chiral C 2-symmetric diamines: (4S,5S)-2,2-dimethyl-4,5-bis(aminomethyl)-1,3-dioxolane, (4S, 5S)-2,2-dimethyl-4,5-bis(methylaminomethyl)-1,3-dioxolane, (4S, 5S)-2,2-dimethyl-4,5-bis(dimethylaminomethyl)-1,3-dioxolane, and (4S, 5S)-2,2-dimethyl-4,5-bis(diphenylaminomethyl)-1,3-dioxolane). The maximum enantiomeric excess of (S)-1-phenylethanol was 24%, that of dimethyl α-methylsuccinate was 38%.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 342–347, February, 2005.  相似文献   

19.
Tertiary alcohols containing the 4,5-bis(dimethylamino)-1-naphthyl group were synthesized. The carbocations that formed from α-methyl-containing alcohols in an acidic medium underwent smooth El elimination to give the corresponding unsaturated derivatives of the “proton sponge” in good yields. At the same time, the carbocation generated from 4-(α-hydroxybenzhydryl)-1,8-bis(dimethylamino)naphthalene was converted into a benzo-[a]fluorene derivative as a result of a complex reaction which has been previously unknown in the chemistry of “proton sponges.” The structure of the latter derivative was established by X-ray diffraction analysis. For Part 26, see Ref. 1; this paper simultaneously presents Part 5 of the series “Resonance-stabilized α-naphthylmethyl carbocations and derived spiro compounds;” for Part 4, see Ref. 2. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1103–1108, June, 2000.  相似文献   

20.
The mass spectra of 1-substituted 3,5-dimethyl-1H-pyrazole-4-carbaldehyde bis(2-hydroxyethyl) dithioacetals and thioacetals were studied for the first time. The main fragmentation pathways of their molecular ions generated under electron impact and chemical ionization were similar. Primary decomposition of the molecular ions of bis(2-hydroxyethyl) dithioacetals involves elimination of 2-sulfanylethanol molecule with formation of the corresponding 1,3-oxathiolane radical cation. Fragmentation of the molecular ions [M]+ · and [M + H]+ derived from 2-(3,5-dimethyl-1H-pyrazol-4-yl)-1,4,6-oxadithiocanes includes cleavage of the eight-membered heteroring and elimination of C4H9OS ·. Substituents in the heteroring of pyrazolecarbaldehydes inhibit decomposition processes related to the aldehyde group.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号