- A New Reaction of Aryl Aldehydes with Aryl Acetylenes in the Presence of Boron Trihalides
-
(matrix presented) The reactions of aryl aldehydes with 2 equiv of arylacetylenes in the presence of boron trichloride yield (E,Z)-1,3,5-triaryl-1,5-dichloro-1,4-pentadienes. Reactions carried out in the presence of boron tribromide generate the corresponding (Z,Z)-1,3,5-dibromo-1,4-pentadienes.
- Kabalka, George W.,Wu, Zhongzhi,Ju, Yuhong
-
-
Read Online
- Carbon Atom Insertion into Pyrroles and Indoles Promoted by Chlorodiazirines
-
Herein, we report a reaction that selectively generates 3-arylpyridine and quinoline motifs by inserting aryl carbynyl cation equivalents into pyrrole and indole cores, respectively. By employing α-chlorodiazirines as thermal precursors to the corresponding chlorocarbenes, the traditional haloform-based protocol central to the parent Ciamician-Dennstedt rearrangement can be modified to directly afford 3-(hetero)arylpyridines and quinolines. Chlorodiazirines are conveniently prepared in a single step by oxidation of commercially available amidinium salts. Selectivity as a function of pyrrole substitution pattern was examined, and a predictive model based on steric effects is put forward, with DFT calculations supporting a selectivity-determining cyclopropanation step. Computations surprisingly indicate that the stereochemistry of cyclopropanation is of little consequence to the subsequent electrocyclic ring opening that forges the pyridine core, due to a compensatory homoaromatic stabilization that counterbalances orbital-controlled torquoselectivity effects. The utility of this skeletal transform is further demonstrated through the preparation of quinolinophanes and the skeletal editing of pharmaceutically relevant pyrroles.
- Dherange, Balu D.,Kelly, Patrick Q.,Levin, Mark D.,Liles, Jordan P.,Sigman, Matthew S.
-
supporting information
p. 11337 - 11344
(2021/08/16)
-
- One-pot, oxidative and selective conversion of benzylic silyl and tetrahydropyranyl ethers to gem-dichlorides using trichloroisocyanuric acid and triphenylphosphine as an efficient and neutral system
-
A one-pot and oxidative method is described for the first time for the conversion of benzylic trimethylsilyl (TMS) and tetrahydropyranyl (THP) ethers to gem-dichlorides using trichloroisocyanuric acid (TCCA) and triphenylphosphine (PPh3) in neutral media. Various theses substrates containing electron withdrawing or donating groups can be efficiently converted to their corresponding gem-dichlorides in good to excellent yields. The present method shows a high degree of chemoselectivity, and due to its one-pot nature is in accordance with green chemistry.
- Khadem Moghaddam, Roqayeh,Aghapour, Ghasem
-
p. 398 - 406
(2020/11/19)
-
- Electrochemical properties and catalytic reactivity of cobalt complexes with redox-active meso -substituted porphycene ligands
-
The cobalt complexes of meso-aryl substituted porphycenes were synthesized and characterized. The reduction potentials of the complexes were shifted to the positive side depending on the strength of the electron-withdrawing properties of the meso-substituents, while the optical properties, such as the absorption spectra of these complexes, were similar. This suggests that the energy levels of the molecular orbitals of the complexes were changed by the meso-substituents while the gaps of the orbitals were not significantly changed. The one-electron reduction of the complex did not afford the Co(I) species, but the ligand-reduced radical anion, which was characterized by electrospectrochemistry. The generated ligand-reduced species reacted with alkyl halides to form the Co(III)-alkyl complex. As a result, the reduction potential of the electrolytic reaction could be directly controlled by the substituents of the porphycene. The catalytic reaction with trichloromethylbenzene was also performed and it was found that the ratio of the obtained products was changed by the reduction potentials of the catalyst, i.e. the cobalt porphycenes.
- Koide, Taro,Zhou, Zihan,Xu, Ning,Yano, Yoshio,Ono, Toshikazu,Luo, Zhongli,Shimakoshi, Hisashi,Hisaeda, Yoshio
-
-
- Synthesis method of benzyl dichloride
-
The invention discloses a synthesis method of benzyl dichloride. The method comprises the steps that a catalyst, an inhibitor and 300 g of methylbenzene are added to a four-neck flask; chlorine is added to the four-neck flask to perform chlorination stage treatment, a chlorinated solution A is made after the chlorination stage treatment is completed; finally distillation stage treatment is conducted on the chlorinated solution A at negative pressure, and the benzyl dichloride is obtained after the stage treatment is completed. A methylbenzene catalytic chlorination method is adopted, one or more of dibenzoyl peroxide, azobisisobutyronitrile and acetamide is taken as the catalyst, aliphatic amine or the derivative thereof is taken as the inhibitor, and the synthesis technology has the advantages of less side reaction, low cost, low energy consumption and simple operation.
- -
-
Paragraph 0013-0024
(2019/05/02)
-
- Organocatalytic Chlorination of Alcohols by P(III)/P(V) Redox Cycling
-
A catalytic system for the chlorination of alcohols under Appel conditions was developed. Benzotrichloride is used as a cheap and readily available chlorinating agent in combination with trioctylphosphane as the catalyst and phenylsilane as the terminal reductant. The reaction has several advantages over other variants of the Appel reaction, e.g., no additional solvent is required and the phosphane reagent is used only in catalytic amounts. In total, 27 different primary, secondary, and tertiary alkyl chlorides were synthesized in yields up to 95%. Under optimized conditions, it was also possible to convert epoxides and an oxetane to the dichlorinated products.
- Longwitz, Lars,Jopp, Stefan,Werner, Thomas
-
p. 7863 - 7870
(2019/06/27)
-
- Halogenation through Deoxygenation of Alcohols and Aldehydes
-
An efficient reagent system, Ph3P/XCH2CH2X (X = Cl, Br, or I), was very effective for the deoxygenative halogenation (including fluorination) of alcohols (including tertiary alcohols) and aldehydes. The easily available 1,2-dihaloethanes were used as key reagents and halogen sources. The use of (EtO)3P instead of Ph3P could also realize deoxy-halogenation, allowing for a convenient purification process, as the byproduct (EtO)3Pa?O could be removed by aqueous washing. The mild reaction conditions, wide substrate scope, and wide availability of 1,2-dihaloethanes make this protocol attractive for the synthesis of halogenated compounds.
- Chen, Jia,Lin, Jin-Hong,Xiao, Ji-Chang
-
supporting information
p. 3061 - 3064
(2018/05/28)
-
- Mild Aliphatic and Benzylic Hydrocarbon C-H Bond Chlorination Using Trichloroisocyanuric Acid
-
We present the controlled monochlorination of aliphatic and benzylic hydrocarbons with only 1 equiv of substrate at 25-30 °C using N-hydroxyphthalimide (NHPI) as radical initiator and commercially available trichloroisocyanuric acid (TCCA) as the chlorine source. Catalytic amounts of CBr4 reduced the reaction times considerably due to the formation of chain-carrying ·CBr3 radicals. Benzylic C-H chlorination affords moderate to good yields for arenes carrying electron-withdrawing (50-85%) or weakly electron-donating groups (31-73%); cyclic aliphatic substrates provide low yields (24-38%). The products could be synthesized on a gram scale followed by simple purification via distillation. We report the first direct side-chain chlorination of 3-methylbenzoate affording methyl 3-(chloromethyl)benzoate, which is an important building block for the synthesis of vasodilator taprostene.
- Combe, Sascha H.,Hosseini, Abolfazl,Parra, Alejandro,Schreiner, Peter R.
-
p. 2407 - 2413
(2017/03/11)
-
- Visible Light-Induced Oxidative Chlorination of Alkyl sp3 C-H Bonds with NaCl/Oxone at Room Temperature
-
A visible light-induced monochlorination of cyclohexane with sodium chloride (5:1) has been successfully accomplished to afford chlorocyclohexane in excellent yield by using Oxone as the oxidant in H2O/CF3CH2OH at room temperature. Other secondary and primary alkyl sp3 C-H bonds of cycloalkanes and functional branch/linear alkanes can also be chlorinated, respectively, under similar conditions. The selection of a suitable organic solvent is crucial in these efficient radical chlorinations of alkanes in two-phase solutions. It is studied further by the achievement of high chemoselectivity in the chlorination of the benzyl sp3 C-H bond or the aryl sp2 C-H bond of toluene.
- Zhao, Mengdi,Lu, Wenjun
-
supporting information
p. 4560 - 4563
(2017/09/11)
-
- Synthesis of Aryldihalomethanes by Denitrogenative Dihalogenation of Benzaldehyde Hydrazones
-
We report a denitrogenative dihalogenation reaction of phenyldiazomethanes in which the hypervalent iodine reagents PhICl2 and TolIF2 act as surrogates for elemental chlorine and fluorine. Halogen transfer from iodane to aryldiazomethane is described, as is a tandem oxidative dihalogenation reaction between iodane and hydrazone. This is the first use of non-α-stabilized diazo compounds in this reaction, which provided an efficient synthesis of aryldifluoromethane (ArCHF2) and aryldichloromethane (ArCHCl2) derivatives. (Figure presented.).
- Zhao, Zhensheng,Kulkarni, Kaivalya G.,Murphy, Graham K.
-
p. 2222 - 2228
(2017/07/07)
-
- Electrolysis of trichloromethylated organic compounds under aerobic conditions catalyzed by the B12 model complex for ester and amide formation
-
The electrolysis of benzotrichloride at -0.9 V vs. Ag/AgCl in the presence of the B12 model complex, heptamethyl cobyrinate perchlorate, in ethanol under aerobic conditions using an undivided cell equipped with a platinum mesh cathode and a zinc plate anode produced ethylbenzoate in 56% yield with 92% selectivity. The corresponding esters were obtained when the electrolysis was carried out in various alcohols such as methanol, n-propanol, and i-propanol. Benzoyl chloride was detected by GC-MS during the electrolysis as an intermediate for the ester formation. When the electrolysis was carried out under anaerobic conditions, partially dechlorinated products, 1,1,2,2-tetrachloro-1,2-diphenylethane and 1,2-dichlorostilibenes (E and Z forms), were obtained instead of an ester. ESR spin-trapping experiments using 5,5,-dimethylpyrroline N-oxide (DMPO) revealed that the corresponding oxygen-centered radical and carbon-centered radical were steadily generated during the electrolyses under aerobic and anaerobic conditions, respectively. Applications of the aerobic electrolysis to various organic halides, such as substituted benzotrichlorides, are described. Furthermore, the formation of amides with moderate yields by the aerobic electrolysis of benzotrichloride catalyzed by the B12 model complex in the presence of amines in acetonitrile is reported.
- Shimakoshi, Hisashi,Luo, Zhongli,Inaba, Takuya,Hisaeda, Yoshio
-
p. 10173 - 10180
(2016/07/06)
-
- One-pot, selective and mild conversion of benzylic alcohols to gem -dichlorides using chlorodiphenylphosphine and 2,3-dichloro-5,6-dicyanobenzoquinone as a new and neutral system
-
A mild and one-pot conversion of benzylic alcohols to their corresponding gem-dichlorides is reported for the first time using chlorodiphenylphosphine (ClPPh2) and 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) in dichloromethane under neutral conditions and at room temperature. The present method can be efficiently used for preparation of gem-dichlorides even in the presence of some other functional groups with excellent chemoselectivity.
- Aghapour, Ghasem,Mohamadian, Samaneh
-
p. 520 - 527
(2015/05/20)
-
- A procedure for Appel halogenations and dehydrations using a polystyrene supported phosphine oxide
-
The conversion of a commercially available polystyrene supported phosphine oxide into synthetically useful polymeric halophosphonium salts using oxalyl chloride/bromide takes place at room temperature in 5 min and generates only CO and CO2 as by-products. The polymeric halophosphonium salts so obtained are useful reagents for Appel halogenations and other dehydrative coupling reactions. This gives rise to a simple three-step synthesis cycle for Appel and related reactions using a commercially available polymeric phosphine oxide with very simple purification and no phosphorus waste.
- Tang, Xiaoping,An, Jie,Denton, Ross M.
-
p. 799 - 802
(2014/02/14)
-
- Rasta resin-triphenylphosphine oxides and their use as recyclable heterogeneous reagent precursors in halogenation reactions
-
Heterogeneous polymer-supported triphenylphosphine oxides based on the rasta resin architecture have been synthesized, and applied as reagent precursors in a wide range of halogenation reactions. The rasta resin-triphenylphosphine oxides were reacted with either oxalyl chloride or oxalyl bromide to form the corresponding halophosphonium salts, and these in turn were reacted with alcohols, aldehydes, aziridines and epoxides to form halogenated products in high yields after simple purification. The polymersupported triphenylphosphine oxides formed as a byproduct during these reactions could be recovered and reused numerous times with no appreciable decrease in reactivity.
- Xia, Xuanshu,Toy, Patrick H.
-
supporting information
p. 1397 - 1405
(2014/07/22)
-
- Efficient partial hydrogenation of trichloromethyl to gem-dichloromethyl groups in platinum on carbon-catalyzed system
-
While gem-dichloromethyl groups can be directly synthesized by the mono-dechlorination of the corresponding trichloromethyl groups, the suppression control of the over-reduction to form chloromethyl or methyl functionalities is quite difficult. We have established the efficient and widely applicable mono-dechlorination method of the trichloromethyl groups to form the corresponding gem-dichloromethyl groups using platinum on carbon in dimethylacetamide as a specific solvent at 25 °C under a hydrogen atmosphere. The mono-dechlorination of the α,α,α- trichloromethylcarbonyl groups smoothly proceeded by the use of platinum on carbon as a catalyst in a highly chemoselective manner, while the efficient mono-dechlorination of the alkyl- and aryl-trichloromethyl groups required the combined use of Bu3SnH.
- Sawama, Yoshinari,Imanishi, Takahiro,Nakatani, Ryosuke,Fujiwara, Yuta,Monguchi, Yasunari,Sajiki, Hironao
-
supporting information
p. 4540 - 4546
(2014/06/10)
-
- Phosphorus(V)-catalyzed deoxydichlorination reactions of aldehydes
-
A phosphine oxide-catalyzed conversion of aldehydes into 1,1-dichlorides is reported. The reaction proceeds via a phosphorus(V)-catalysis manifold in which phosphine oxide turnover is achieved using oxalyl chloride as a consumable reagent. The new method is applicable to a range of aldehydes and, in combination with palladium-catalyzed reductive dimerization, gives rise to a new catalytic approach to the synthesis of stilbenes and a short formal synthesis of resveratrol.
- An, Jie,Tang, Xiaoping,Moore, Joshua,Lewis, William,Denton, Ross M.
-
p. 8769 - 8776
(2013/09/23)
-
- Facile conversion of aldehydes and ketones to gem-dichlorides using chlorodiphenylphosphine/N-chlorosuccinimide as a new and neutral system
-
Aldehydes and ketones are easily converted to their corresponding gem-dichlorides using a mixture of chlorodiphenylphosphine and N-chlorosuccinimide (ClPPh2/NCS) in dichloromethane under neutral conditions and at room temperature. Copyright Taylor & Francis Group, LLC.
- Aghapour, Ghasem,Afzali, Asieh
-
experimental part
p. 4023 - 4035
(2009/04/11)
-
- Chemo- and stereoselectivity of the reaction of aromatic aldehydes with triphenylphosphine and trichloroacetic acid derivatives
-
Aromatic aldehydes react with triphenylphosphine and ethyl trichloroacetate or trichloroacetonitrile to give the corresponding benzylidene dichlorides or α-chlorocinnamic acid derivatives. The chemo- and regioselectivity of these reactions depend on both the substituent in the aromatic ring and reaction conditions. The product configuration was determined on the basis of the coupling constants 2JCH and 3JCH in the 13C NMR spectra. Pleiades Publishing, Inc., 2006.
- Matveeva,Erin,Osetrov,Leshcheva,Kurts
-
p. 388 - 392
(2007/10/03)
-
- Inter- and innermolecular reactions of chloro(phenyl)carbene
-
Supramolecular photolyses of 3-chloro-3-phenyl-3H-diazirine (8) were performed within cyclodextrin (CyD) hosts to determine whether these toroidal inclusion compounds could alter the reactivity of the ensuing carbene reaction intermediate, chloro(phenyl)carbene (9). Remarkably, no intramolecular products stemming from carbene 9 could be detected. Instead, modified CyDs were formed via so-called innermolecular reactions. Hence, diazirine 8 was photolyzed in various conventional solvents to gauge the intermolecular reactivity of carbene 9. Relevant results were used to rationalize the CyD innermolecular reaction products.
- Rosenberg, Murray G.,Brinker, Udo H.
-
p. 4819 - 4832
(2007/10/03)
-
- Nitrogen-based halogenating agents and process for preparing halogen-containing compounds
-
Disclosed are a fluorinating agent represented by the general formula (1): wherein R1to R4are a substituted or unsubstituted, saturated or unsaturated alkyl group or a substituted or unsubstituted aryl group, and can be the same or different; R1and R2or R3and R4can bond to form a ring including a nitrogen atom or a nitrogen atom and other hetero atoms; or R1and R3can bond to form a ring including a nitrogen atom or a nitrogen atom and other hetero atoms, for example: a preparation process of the fluorinating agent and a process for preparing fluorine compounds by reacting various compounds with the fluorinating agent. The invention has also disclosed that the fluorinating agent is very effective for fluorinating oxygen containing functional compounds.
- -
-
-
- Alkylation of aromatic aldehydes with alkylboron chloride derivatives
-
The reaction of aryl aldehydes with alkylboron chlorides has been investigated. Monoalkylboron dichlorides react with aryl aldehydes in hexane under reflux conditions to give a mixture of dichloroarylmethane and benzyl chloride. Under the same reaction conditions, dialkylboron chlorides lead to formation of a mixture of benzyl chloride and the chloroalkylation product. In the presence of a base such as 2,6-lutidine, the reactions of monoalkylboron dichlorides with aryl aldehydes yield small amounts of the desired alkylation products at room temperature. Dialkylboron chlorides react with aryl aldehydes in hexane in the presence of base to generate the corresponding arylalkylmethanols in good yields.
- Kabalka, George W,Wu, Zhongzhi,Ju, Yuhong
-
p. 1663 - 1670
(2007/10/03)
-
- Conversion of aromatic aldehydes to gem-dichlorides using boron trichloride. A new highly efficient method for preparing dichloroarylmethanes
-
The chlorination of aromatic aldehydes with boron trichloride in hexane under reflux conditions produces the corresponding dichloromethyl derivatives in excellent yields. (C) 2000 Elsevier Science Ltd.
- Kabalka, George W.,Wu, Zhongzhi
-
p. 579 - 581
(2007/10/03)
-
- Reaktionen von Ph2SbH und p-TolSbH2 mit organischen Verbindungen
-
p-TolSbH2 reacts with styrene with formation of ethylbenzene and (p-TolSb)n (n=4, 5 in benzene). The action of phenyl acetylene on p-TolSbH2 gives styrene. Addition of Ph2SbH on phenyl acetylene in the presence of AIBN (azodiisobutyronitrile) yields 95% trans- and 5% cis-PhCH=CHSbPh2. Ph2SbH reacts with benzaldehyde in the presence of AIBN with formation of benzylalcohol (98%) and with various prochiral ketones in the presence of chiral auxiliares to give alcohols in high optical yields. Benzotrichloride reacts with Ph2SbH in the presence of PdCl2 to give benzylidene chloride. 1-Bromo adamantane, dibromo cholestanol, 2-chloro acetophenone, cinnamic acid chloride, and chloro acetophenone react with Ph2SbH/AIBN with substitution of the halogen atoms by hydrogen. Benzylbenzoate is formed the by action of Ph2SbH/AIBN on benzoyl chloride.
- Breunig,Probst
-
p. 297 - 303
(2007/10/03)
-
- New applications of tungsten hexachloride (WCl6) in organic synthesis. Halo-de-hydroxylation and dihalo-de-oxo-bisubstitution reactions
-
Tungsten hexachloride (WCl6) has been used for the halo-de-hydroxylation and dihalo-de-oxo-bisubstitution reactions of benzylic alcohols, benzaldehydes, acyloins, and epoxides to their chlorides, gem-dichlorides, vic-trichlorides, and vic-dichlorides respectively.
- Firouzabadi, Habib,Shiriny, Farhad
-
p. 14929 - 14936
(2007/10/03)
-
- Cobalt(salen)-electrocatalyzed conversion of benzotrichloride into tolane. A triply catalytic and overall quintuple electrochemical transformation
-
Electrochemical reduction of a mixture of cobalt(II)(salen) and benzotrichloride (4) results in transformation of 4 successively into 1,1,2,2-tetrachloro-1,2-diphenylethane, 1,2-dichlorostilbene, diphenylacetylene, stilbene, and bibenzyl. The first three reactions are electrocatalyzed by the cobalt complex; the last two are direct reductions.
- Kaufman, Seth A.,Phanijphand, Twan,Fry, Albert J.
-
p. 8105 - 8108
(2007/10/03)
-
- Process for preparing 4,5-difluorobenzaldehydes
-
4,5-Difluorobenzaldehydes of a given formula are prepared by the reaction of corresponding benzaldehydes with a fluorinating agent.
- -
-
-
- A Kinetic and Mechanistic Study of the Self-Reaction and Reaction with H2O of the Benzylperoxy Radical
-
The kinetics and mechanism of the reactions C6H5CH2O2 + C6H5CH2O2 -> 2C6H5CH2O + O2 (3a), C6H5CH2O2 + C6H5CH2O2 -> C6H5CHO + C6H5CH2OH + O2 (3b), and C6H5CH2O2 + HO2 -> C6H5CH2OOH + O2 (4) have been investigated using two complementary techniques: flash photolysis/UV absorption for kinetic measurements and continuous photolysis/FTIR spectroscopy for end-product analyses and branching ratio determinations.The reaction of chlorine atoms with toluene was found to yield benzyl radicals exclusively and was used to generate benzylperoxy radicals in excess oxygen.During this study, relative reaction rate constants of chlorine atoms with compounds related to those involved in the reaction mechanism have been measured at room temperature: k(Cl+toluene) = (6.1 +/- 0.2)E-11, k(Cl+benzaldehyde) = (9.6 +/- 0.4)E-11, k(Cl+benzyl chloride) = (9.7 +/- 0.6)E-12, k(Cl+benzyl alcohol) = (9.3 +/- 0.5)E-11, k(Cl+benzene) 3 molecule-1 s-1.The products identified following the self-reaction 3 were benzaldehyde, benzyl alcohol, and benzyl hydroperoxide.The latter is the product of the reaction of C6H5CH2O2 with HO2.The yield of products allowed us to determine the branching ratio α = k3a/k3 = 0.4.The UV absorption spectrum of the benzylperoxy radical was determined from 220 to 300 nm.It was similar to those of alkylperoxy radicals, with a maximum cross section at 245 nm of 6.8E-18 cm2 molecule-1.Kinetic data were obtained from the detailed simulation of experimental decay traces recorded at 250 nm over the temperature range 273-450 K.The resulting rate expression are k3 = (2.75 +/- 0.15)E-14 exp cm3 molecule-1 a-1 and k4 = (3.75 +/- 0.32)E-13 exp3 molecule-1 s-1 (errors = 1?).The UV absorption traces in the flash-photolysis kinetic study were well accounted for by the identified products in the FTIR study, thus providing good confidence in the results.However, about 20percent of the products have remained unidentified.Some uncertainties persist in the reaction mechanism leading us to assign a fairly large uncertainty of about 50percent to the rate constants k3 and k4 over the whole temperature range.This work shows that the aromatic substituent does not provide any specificity in the reactivity of peroxy radicals and confirms that large radicals tend to react faster with HO2 than generally assumed in current atmospheric models.
- Noziere, Barbara,Lesclaux, Robert,Hurley, Michael D.,Dearth, Mark A.,Wallington, Timothy J.
-
p. 2864 - 2873
(2007/10/02)
-
- A simple synthesis of gem-bromochlorocyclopropanes via phase-transfer catalysis
-
Substituted 1-bromo-1-chlorocyclopropanes 2 were synthesized from dibromomethane, phenyltrichloromethane trichloride and alkenes 1 in the presence of 60% aqueous potassium hydroxide and tetrabutylammonium hydrogen sulfate as a catalyst (PTC system), in good yields.
- Balcerzak,Jonczyk
-
p. 857 - 858
(2007/10/02)
-
- Versatility of Zeolites as Catalysts for Ring or Side-Chain Aromatic Chlorinations by Sulfuryl Chloride
-
Zeolites catalyze chlorination of aromatics by sulfuryl chloride SO2Cl2.It is possible by an appropriate choice of the catalyst to effect at will, with very high selectivity, either the ring or the side-chain chlorination.Zeolite ZF520 is the choice catalyst for the former, because of its high Broensted acidity.Zeolite NaX (13X) is a fine catalyst for the latter, free-radical chlorination; the reaction is best effected in the presence of a light source; the catalyst can be reused many times with no loss in activity.Both reaction modes, the ionic (ring chlorination)and the radical (side-chain substitution), are likely to occur outside of the channel network in the microporous solid.The effects of various experimental factors - such as the nature of the solvent, the reaction time and temperature, the Broensted acidity of the solid support, the presence of radical inhibitors, and the quantity of catalysts - were investigated.The procedures resulting from this study are very easy to implement in practice and are quite effective.
- Delaude, Lionel,Laszlo, Pierre
-
p. 5260 - 5269
(2007/10/02)
-
- A laser flash photolysis study of carbonyl ylides of arylchlorocarbenes: Kinetics and reversibility of the formation, cyclization, and cycloaddition
-
Carbonyl ylides formed from (p-nitrophenyl)chlorocarbene or phenylchlorocarbene and acetone or benzaldehyde have been studied by laser flash photolysis. The rate constants for the formation of these ylides, for their cyclization to oxiranes, and for some addition reactions have been measured. Electron-withdrawing substituents on the carbene increase the rate of ylide formation and decrease the rate of cyclization. The trapping of carbonyl ylide and para-substituted benzaldehydes gave a Hammett's ρ value equal to +1.0. The dual role of benzaldehyde, first as a constituent of the ylide and second as a trapping agent, has been demonstrated. Kinetic analysis indicates that an equilibrium exists between the phenylchlorocarbene, the acetone, and the corresponding ylide, with an equilibrium constant around 0.27 M-1 at 300 K.
- Bonneau,Liu
-
p. 744 - 747
(2007/10/02)
-
- The reaction of benzotrihalides and benzal halides with magnesium. Synthetic and mechanistic studies
-
The benzotrihalides (PhCX3) where X = Cl, Br, and F were allowed to react with magnesium in THF at room temperature.When the halide was chloride or bromide, the trihalide gave diphenylacetylene in high yield in addition to several minor products which were identified.No reaction was observed when the halide was fluoride.When the corresponding dichloride was allowed to react with magnesium in THF, stilbene was formed as the major product.The possible mechanisms for these reactions are discussed.
- Ashby, E. C.,Al-Fekri, Dheya M.
-
p. 275 - 292
(2007/10/02)
-
- AN EFFECTIVE CHLORINATING AGENT BENZYLTRIMETHYLAMMONIUM TETRACHLOROIODATE, BENZYLIC CHLORINATION OF ALKYLAROMATIC COMPOUNDS
-
The reaction of alkylaromatic compounds with benzyltrimethylammonium tetrachloroiodate in carbon tetrachloride in the presence of AIBN under reflux for several hours gave α-chloro-substituted compounds in fairly good yields.
- Kajigaeshi, Shoji,Kakinami, Takaaki,Moriwaki, Masayuki,Tanaka, Toshio,Fujisaki, Shizuo
-
p. 5783 - 5786
(2007/10/02)
-
- Cathodic Addition of Benzylidyne Trichloride to Ketones and Aldehydes
-
Ketones are converted to homologated enones 7a-g in good yields by cathodic addition of benzylidyne trichloride (1d).As intermediates α-Chlorooxiranes 6 are assumed, which rearrange via α-keto carbenium ions 9 to enones.The intermediacy of 9 is supported by the addition of 1d to norcamphor, where the products indicate equilibrating norbornyl cations as intermediates. α,β-Unsaturated ketones lead depending on steric shielding of the double bond to the cyclopropane 23 as 1,4-adduct or the enone 26 as 1,2-adduct.With aldehydes and 1d, α-chloro or βhydroxy ketones, the conversion products of 2-chlorooxiranes, are obtained.
- Steiniger, Michael,Schaefer, Hans J.
-
p. 125 - 132
(2007/10/02)
-
- Oxidation using Phase Transfer Catalyst - A Mechanistic Study
-
Oxidation of benzyl alcohol and benzyl cyanide by sodium hypochlorite under phase transfer conditions involves initial chlorination at the benzylic carbon.Since no reaction takes place in the absence of a phase transfer catalyst, it clearly indicates involvement of an ionic species in the organic phase.
- Mathur, S. N.,Rao, S. Nagabushan,Bhalerao, U. T.
-
-
- Hexamethylphosphoramide Catalyzed Conversion of Carbonyl Compounds into geminal-Dichlorides with Thionyl Chloride
-
α, β-Unsaturated and aromatic aldehydes can be converted into geminal-dichlorides quantitatively by reaction with thionyl chloride in the presence of catalytic amounts of hexamethylphosphoramide at room temperature
- Khurana, J. M.,Mehta, Sanjay
-
-
- Reaction of Phenylchlorocarbene in Oxygen-Doped Matrices
-
Irradiation of phenylchlorodiazirine at 10 K matrix isolated in argon gives phenylchlorocarbene.The carbene was characterized by IR, UV, and trapping with HCl.Warming an argon matrix containing O2 and the carbene to 35 K caused reaction to give the corresponding carbonyl oxide.The yellow-green (λmax 400nm) carbonyl oxide was characterized by IR, Uv, and 18O2 labeling.Photolysis of the carbonyl oxide with visible light gave the corresponding dioxirane, benzoyl chloride, and ozone.The dioxirane, which showed only absorption tailing into the visible, was characterized by IR, 18O2 labeling, and subsequent photochemistry.Irradiation of the dioxirane (λ>/=420 nm) gave mainly phenyl chloroformate and a small amount of chlorobenzene and CO2.Possible mechanism for the novel spin-forbidden O2 addition are discussed.
- Ganzer, Georg A.,Sheridan, Robert S.,Liu, Michael T. H.
-
p. 1517 - 1520
(2007/10/02)
-
- TRANSFORMATION OF PHENYLCHLORODIAZIRINES TO 1,3-DIOXOLANES AND A 1,3-DITHIOLANE
-
Chlorophenylcarbene reacts with bifuncional or polyfuncional alcohols and ethanedithiol to form 2-phenyl-1,3-dioxolanes and 2-phenyl-1,3-dithiolane.
- Liu, Michael T.H.,Kokosi, Joseph
-
p. 3049 - 3053
(2007/10/02)
-
- Electrochemical Reduction of Trichloromethylbenzene II Reduction in the Presence of Electrophiles
-
Electrochemical reduction of trichloromethylbenzene at a mercury electrode in DMF/TBABF4 in the presence of acetic anhydride gives 1,2-diacetoxy-1-phenylpropene as major product; minor products are dichloromethylbenzene and dimerized products.During the reduction 1,1-dichloro-1-phenyl-2-propane and 2-acetoxy-1-chloro-1-phenylpropene can be detected.With sodium perchlorate as supporting electrolyte 1-chloro-1-phenyl-2-propanone and 1-acetoxy-1-phenyl-2-propanone are formed; these products are also formed during the reduction of benzal chloride in the presence of acetic anhydride.Reductive carboxylation of trichloromethylbenzene gives 2,2-dichloro-2-phenylacetic acid.
- Gisselbrecht, Jean-Paul,Lund, Henning
-
p. 823 - 828
(2007/10/02)
-
- Electrochemical Reduction of Trichloromethylbenzene
-
The electrochemical reduction of trichloromethylbenzene (benzotrichloride) has been investegated by cyclic voltammetry, pulse polarography, and preparative scale reductions.Depending on conditions, benzal chloride, benzyl chloride, 1,2-diphenyl-1,1,2,2-tetrachloroethane, Z- and E-1,2-dichloro-1,2-diphenylethylene, and diphenylacetylene may be obtained.At a mercury electrode at the potential of the prewave the main products are 1,2 -diphenyl-1,1,2,2-terachloroethane (ca.60 percent) and diphenylacetylene (ca.25 percent); at a more negative potential benzal chloride is the main product with low yields of dimerized products. 1,2-Diphenyl-1,1,2,2-tetrachloroethane is reduced to a mixture of Z- and E-1,2,-dichloro-1,2-diphenylethene which in turn is reduced to diphenylacetylene.
- Gisselbrecht, Jean-Paul,Lund, Henning
-
p. 773 - 778
(2007/10/02)
-
- Dichlorocarbene from Flash Vacuum Pyrolysis of Trimethyl(trichloromethyl)silane. Possible Observation of 1,1-Dichloro-3-Phenyl Carbonyl Ylide
-
Flash vacuum pyrolysis of trimethyl(trichloromethyl)silane 3 at 500-700 deg C was shown to be a simple and efficient method for the production of :CCl2 in the gas phase.The copyrolysis of silane 3 and benzaldehyde (7) at 600 deg C led to 1,1,1-trichloro-2-phenyl-2-(trimethylsiloxy)ethane (8), a 1:1 adduct, in addition to benzal chloride (15) and α-chlorophenylacetyl chloride (16), product thought to arise from 1,1-dichloro-3-phenyl carbonyl ylide 17 as outlined in Scheme I.An orange-red material trapped at deg K could be photobleached as well as thermally bleached and had an IR band at 1650 cm-1 and a si gnificant absorption with λmax 510 nm (and a broad shoulder at a 580 nm).
- Gisch, John F.,Landgrebe, John A.
-
p. 2050 - 2054
(2007/10/02)
-
- Kinetics and Equilibria of Chloride Transfer Reactions. Stabilities of Carbocations Based on Chloride and Hydride Transfer Equilibria Measurements
-
The kinetics of a number of gas-phase chloride transfer reactions R0(1+)+RCl=R0Cl+R(1+) were measured with a pulsed electron high pressure mass spectrometer.Most of the reactions were found to occur near the collision limit, i.e., with rate constants k ca. 10-9 molecules-1 cm3 s-1.However, several reactions were much slower and were exhibiting negative temperature dependence, i.e., decreasing rate with increasing temperature.Hydride and chloride transfer equilibria were determined for various carbocations R(1+) (R=isopropyl, cyclopentyl, tert-butyl, 1-methylcyclopentyl, substituted benzyls, norbornyl, 2-methyl-2-norbornyl, and adamantyl).Excellent agreement with earlier hydride transfer measurements of Solomon, Meot-Ner, and Field were observed.The chloride affinities generally support conclusions based on the hydride transfer data.Discussion of the data in connection with benzyl cation substituent effects, the norbornyl cation stability, and solvent effects on carbocation stability is presented.The data show that the 2-norbornyl cation is unusually stable.Significant differences between carbocation R(1+) stabilities in gas phase and solution are found which suggest that both differential nucleophilic solvent stabilization and differential nonspecific solvation occur in solution.
- Sharma, R. B.,Sharma, D. K. Sen,Hiraoka, K.,Kebarle, P.
-
p. 3747 - 3757
(2007/10/02)
-
- Process for the preparation of benzal chlorides
-
Process for the preparation of benzal chlorides from benzotrichlorides, according to which benzotrichlorides are reacted with thiols in the presence of metal salts at elevated temperatures.
- -
-
-
- THE PHASE TRANSFER CATALYSED PREPARATION OF 2-METHYL-2-TRICHLOROMETHYL-3-PHENYLOXIRANE
-
A phase transfer catalyst has been used to prepare the title compound and other highly chlorinated compounds from phenylpropanone and carbon tetrachloride.
- Reeves, W. Preston,Creswell, Mark W.
-
p. 945 - 950
(2007/10/02)
-
- MECHANISMS OF EPOXIDATIONS AND CHLORINATIONS OF HYDROCARBONS BY INORGANIC HYPOCHLORITE IN THE PRESENCE OF A PHASE-TRANSFER CATALYST.
-
Inorganic hypochlorite in the presence of a quarternary ammonium salt (phase-transfer catalyst) not only epoxidizes several arenes to arene oxides in high yields but also converts toluene to alpha -chlorotoluene, anisole to ring chlorinated anisoles, and alkenes to a complex mixture of chlorinated and oxidized products, including the epoxide. More detailed studies with this system indicate the following: (1) the high-yield conversion of toluenes to benzyl chlorides proceeds with a deuterium isotope effect of 3. 6 and a rho ** plus value of minus 1. 7: (2) p-chloroanisole is the major product from anisole and is formed in a 22-fold greater quantity than o-chloroanisole; (3) the epoxidation of cis- and trans-alkenes is stereoselective but not completely stereospecific; (4) the chlorination of saturated hydrocarbons occurs with a selectivity that is experimentally identical with that of chlorine monoxide.
- Fonouni,Krishnan,Kuhn,Hamilton
-
p. 7672 - 7676
(2007/10/02)
-
- SPONTANEOUS RADICAL CHLORINATION OF TOLUENE IN THE SIDE CHAIN
-
The effect of oxygen on the rate of radical chlorination of toluene in the side chain was investigated.It was shown that if oxygen dissolved in the toluene is removed by blowing the toluene with inert gass (carbon dioxide or nitrogen) and chlorine not con
- Serguchev, Yu. A.,Moshkin, V. F.,Konoval, Ya. V.,Stetsyuk, G. A.
-
p. 908 - 910
(2007/10/02)
-