A CHEMICAL STUDY OF THE HALOGENATION OF SELECTED TERPENES (original) (raw)
Journal of The American Chemical Society, 1975
Both groups attribute smooth curvature in log rate Constant vs. log aHB plots to variation in log (fsn+/f+). (31) Note that we are taking a ratio of activity coefficients and then the log of that ratio which greatly helps to even out nonlinear behavior. Abstract: Irradiation of exo-tricyclo[3.2.1 .02s4]octane and tert-butyl hypochlorite at 4 0 ' in CC14 generates a mixture of monochlorides which consists of exo-6-chloro-, endo-6-chloro-, and l-chloro-exo-tricyclo[3.2.1 .02s4]octane in a ratio of 67: 12: 17. In contrast, radical chlorination of endo-tricyclo[3.2.1 .02.4]octane with tert-butyl hypochlorite results in a mixture of monochlorides consisting of anti-8-chloro-endo-tricyclo[3.2.1 .02*4]octane, endo-2-chlorotricyclo[3.3.0.04~6]octane, and two incompletely characterized components in a 66:27:5:2 ratio. Analogous radical chlorination of exo,exo-tetracyclo[3.3.1.-02.4.06.8]nonane with tert-butyl hypochlorite yields 1-chloro-and 2-chlorotetracyclo[3.3.1 .02~4.06~8]nonane in a ratio of 71: 22, while photochlorination of exo,endo-tetracyclo[3.3.1.0*~4.06~*]nonane with tert-butyl hypochlorite gives 1-chloro-and 6chloro-exo,endo-tetracyclo[3.3.1 .02.4.06~8]nonane and endo-9-chloro-exo-tetracycl0[4.3.O.O*~~.0~~~]n0nane in a ratio of 44:
Chemistry of N-halamines. XVI. Chlorination of alkenes with trichloramine
Journal of Organic Chemistry, 1971
Trichloramine in nonpolar solvent gave excellent yields of vicinal dichlorides with certain types of olefins. Nitrogen was generated almost quantitatively, along with the by-products, ammonium chloride and basic material. With 1-hexene, 1-octene, cyclopentene, cyclohexene, 3-chloropropene, and 1,1-dichloroethylene as substrates, yields of the corresponding vic-dichlorides ranged from 89 to 97%. The meso:dZ ratios for chlorination of the isomeric 2-butenes were similar to those obtained from molecular chlorine under radical conditions. Additional evidence for a radical mechanism was derived from relative reactivities, catalysis, formation of some cis-1,2dichlorocyclohexane from cyclocyclohexene, and participation of an alkane additive. The high addition: substitution ratios suggest that free chlorine atoms are generated in no more than minor amounts. The detailed aspects of the radical pathway are discussed.
The Journal of Physical Chemistry A, 1999
Cavity ring-down spectroscopy (CRDS), end-product analysis, and ab initio calculations have determined absorption cross sections, rate coefficients, reaction mechanisms, and thermochemistry relevant to the addition of halogen atoms to propargyl chloride and propargyl bromide. Halogen atoms were produced by laser photolysis, and the addition reaction products were probed at a variable delay by CRDS using a second laser pulse. We report the continuum spectra of C 3 H 3 Cl 2 (1,2-dichloroallyl), C 3 H 3 ClBr (1-chloro-2-bromoallyl), and C 3 H 3 Br 2 (1,2-dibromoallyl) radicals between 238 and 252 nm and the absorption cross sections, σ 240 (C 3 H 3 -Cl 2 ) ) (4.20 ( 1.05) × 10 -17 cm 2 molecule -1 and σ 242 (C 3 H 3 Br 2 ) ) (1.04 ( 0.31) × 10 -17 cm 2 molecule -1 . When the observed data are fit to complex reaction schemes, the 298 K rate coefficients for formation of 1,2-dihaloallyl radicals at 665 Pa were found to be k(Cl + C 3 H 3 Cl) ) (1.2 ( 0.2) × 10 -10 cm 3 molecule -1 s -1 and k(Br + C 3 H 3 Br) ) (2 ( 1) × 10 -12 cm 3 molecule -1 s -1 . At 298 K and 665 Pa the self-reaction rate coefficients of these radicals were found to be k(C 3 H 3 Cl 2 + C 3 H 3 Cl 2 ) ) (3.4 ( 0.9) × 10 -11 cm 3 molecule -1 s -1 and k(C 3 H 3 Br 2 + C 3 H 3 Br 2 ) ) (1.7 ( 1.1) × 10 -11 cm 3 molecule -1 s -1 . The listed uncertainties are twice the standard deviation of individual determinations, and those for rate coefficients include the uncertainty of the appropriate absorption cross section. † NIST/NRC Postdoctoral Associate 1995-1997.
New routes to 1,1-dichloro-4-methyl-1,3-pentadiene
Tetrahedron, 1984
1, l, l-trichloro-Z-hydroxy-4-methyl-pentene-3 lb) was chlorinated to afford tri-and tetra-chlorinated compoun & s 2,3,4. Compounds 2 and 2 were transformed by reductive dechlorinatioii into l,l,-aichloro-4-methyl-1,3-pentadiene @JJ. Another route starting from the same alcohol or its isomer was also developed.
Reactions of t-acetylenic halides with grignard reagents
Tetrahedron, 1965
The diacetylenic chloride, 6chlorcFdmethyl-2&heptadiyne (I) reacted with methylmagnesium bromide to give a complex mixture of products, including the allene, 2-methyl-2,3heptadien-5-yne (III). The treatment of the acetylenic dichloride, 2,5dichloro-2,5-dimethyl-3hexyne (VI) with methylmagnesium bromide gave the cumulene, 2,Sdimethyl-2,3,4atriene (VII), and a similar reaction with 2,7-dichloro-2,7dimethyl-3,S+ctadiyne yielded the extremely unstable cumulene, 2,7dimethyl-2,3,4,5&octapentaene (XII). The formation of these compounds can be explained by a functional exchangeelimination mechanism involving radicals.
The free radical reaction between alkanes and carbon tetrachloride
Journal of the American Chemical Society
Product studies and kinetic electron paramagnetic resonance methods were used to investigate the free radical reaction between alkanes and carbon tetrachloride in solution. Trichloromethyl radicals abstracted hydrogen from simple alkanes with rate constants of ca. 60 M-I C1 at 300 K, in good agreement with gas-phase data. However, rate constants for chlorine abstraction by alkyl radicals from carbon tetrachloride were ca. lo4 M-I S-I and were therefore ca. 2 orders of magnitude higher in solution than in the gas phase. Possibilities for the origin of this effect a r e discussed.
Tetrahedron Letters, 1994
Methyl cechlon-~ or a,adichloroastars are cbtained in excellent yields by oxidation chlorination of 2-alkyl-4,S-dimethyl-1,3-dioxolanes with trichl~socyanuric acid Esters of a,a-dichloro-carboxylic acids are use&l intemu&tes in the preparation of a-chloro-esters1 and of glycidic esters,2~3 through the Darzens reaction. General procedures for the synthesis of these dihaloeaters have been till now limited to the alkylation of dichloroacetates3 and to the Hell-Volhard-Zelinakii chlorination of carboxylic acids.5 However, the former method, though being more versatile, follows a very complicated procedure and the second one uses drastic reaction conditions. A preparation of a,a-dihaloesters by halogenation of ketene thioacetals has been alao reported, but without experimental detaih~ and yields.5
Controlling the action of chlorine radical: from lab to environment
The strength of Bz---Cl• complexation has been explored using density functional theory (DFT) calculations, including dispersion-corrected (DFT-D) calculations. Of the methods tested, the ωB97X-D method seems the best performing, along with the previously tested MPW1K method. The effect of substituent (X=NO2, F, Cl, Br, H, CH3, OCH3, OH, NH2 and N(CH3)2) on the stabilities of the Ar---Cl• π-like intermediates show a good correlation with the linear free energy relationships used experimentally, but this is not the case for Ar---Cl• σ-complexes, suggesting the π-complex as the experimentally active abstracting agent. The role of PAH and lignin derivatives in mediating chlorination reactions in nature is explored. Stable π-complexes were identified for lignin derivatives, indicating humic substances may mediate chlorine atom reactivity at the marine boundary layer, in addition to forming chlorolignins.
Journal of Organic Chemistry, 1989
Perchlorotriphenylmethyl radical (P T M) is the paradigm of the chlorine-shielded "inert free radicals" (IF%), which owe their unique chemical inertia to the colossal overcrowding about their trivalent carbon. However, they are active in single electron-transfer processes. The present paper reports and describes a remarkable twc-step chlorination of PTM' consisting of a SET, giving the corresponding carbenium ion (PTM+), followed by chlorideion addition yielding ClsClle. The latter is not the would-be conventional, extremely overcrowded perchlorotriphenylmethane (CY adduct), but the less-strained perchloro(diphenylmethylene)cycylohexa-1,4-diene (para adduct), as shown by spectral and X-ray data analyses. This and other abnormal reactivity processes and phenomena are described and accounted for in terms of great repulsions among the chlorines. The SET leading to cation PTM+ is conducted by either SOzClz/A1C13 or by CHzClZ/AlCl3. The subsequent chloride-ion addition results from chlorine bridging between PTM+ and counter-ion A1Cl4-. 4 (c6c15)2c,
Relative reactivity of chloroprene and methyl methacrylate toward initiator radicals
European Polymer Journal, 2003
The relative rates of addition of chloroprene (CP) and methyl methacrylate (MMA) toward small model radicals structurally similar to the poly(MMA), poly(methacrylonitrile) and poly(styrene) radical was investigated following the method of Bevington and Huckerby [J Polym Sci Polym Chem 20 (1982) 2655. Results indicate that these small radicals are significantly more selective toward CP than the corresponding polymer radicals, consistent with earlier reports that penultimate unit effects may be important in the copolymerisation of CP with MMA and styrene. As previous investigations of substituted dienes by the end-group method have given similar results for polymer radicals and small model radicals, this may constitute evidence for a penultimate unit effect that is predominantly electronic rather than steric in origin.
J Org Chem, 1981
Reaction of Silver Acetate and Iodine with lg. Starting materials were 0.735 g of silver acetate and 0.396 g of lg; purification of the crude reaction product by preparative layer chromatography (CHC13) afforded 0.360 g (72%) of pure 2iodocyclooctanone, 6c: molecular distillation 45 "C (2 mm) [lit? 45 OC (1.75 mm)]; nzsD 1.5490 (lita5 n23D 1.5494); IR (neat) 1700 cm-'. Reaction of Silver Benzoate and Iodine with lg. Starting materials were 1.010 g of silver benzoate and 0.396 g of lg; purification of the crude reaction product by preparative layer chromatography (CHC13) afforded 0.356 g (71%) of pure 6c: molecular distillation 45 "C (2 mm) [lita5 45 OC (1.75 mm)]; IR (neat) 1700 cm-'. Reaction of Silver Acetate and Iodine with lh. Starting with 0.735 g of silver acetate and 0.508 g of l h afforded a 1:4 mixture (NMR) of 3q and 6d. Preparative layer chromatography (CHCld of the mixture afforded pure 2-acetoxycyclododecanone, 3q, and 2-iodocyclododecanone, 6d. 2-Acetoxycyclododecanone, 3q: 0.072 g (15%); mp 83-84
Radical Chlorination of Polyethylene and Molecular Structure Characterization of Reaction Products
Polymer Journal, 2005
In this research the radical chlorination reaction of polyethylene has been carried out in perchloroethylene solvent under atmospheric pressure, using chlorine gas and UV light. In order to characterize the structural configuration of chlorinated polymer and study the reaction rate, different samples have been taken in equal periods of time during the reaction time. The FT-IR and H NMR spectra of these samples have been recorded and interpreted. The sequences of methylene groups between two subsequent chloromethylene groups in the polymeric chains have been determined through H NMR spectra and the obtained results have been confirmed with the data of some model compounds. The relative percentage of these methylene groups, which have been calculated from their integrated values in their H NMR spectra have been plotted vs. percentage of chlorination and discussed. Also H NMR spectra have been used for calculating the chlorine percentage of each sample and the results have been compared with data obtained from an elemental analyzing technique namely flask combustion method. Using the results of these two techniques, the reaction rate has been plotted versus reaction time and compared. [
Reaction of Some Alkenols with Tetrachloromethane
Monatshefte für Chemie/Chemical Monthly, 2000
The reaction of some alkenols with tetrachloromethane in the presence of a radical initiator was investigated. Regarding the effects of structural features of the starting alkenol (number and position of methyl substituents at the double bond and at the carbinol carbon atom, constitutional relationship between the double bond and the hydroxyl group) there are two possible competing reactions: addition and cyclization. In the case of the simplest alkenols (without substituents and with a more remote double bond) addition occurs; mono-and disubstituted secondary and tertiary Á 4 -and Á 5 -alkenols cyclize in high yields to give the corresponding cyclic ethers.
Australian Journal of Chemistry, 1987
The complexes, (C5H5)3M( py ) (M = Nd, Sm, Eu or Yb ), (C5H5)2Eu( py ), and (C5H5)2Yb( py )2 have been prepared from the appropriate lanthanoid elements and thallous cyclopentadienide in pyridine, and (C5H5)3M( NCMe ) (M = Nd , Sm or Yb ) and (C5H5)2Yb( NCMe ) from similar reactions in acetonitrile. Ligand exchange or addition has also been used to give (C5H5)3Sm( py ), (C5H5)2Yb( py )2 and (C5H5)2Yb( NCMe ). Ytterbium metal reduces (C5H5)3Yb( py ) in pyridine to (C5H5)2Yb( py )2, which is oxidized back to (C5H5)3Yb( py ) by TI(C5H5). Europium with (C5H5)2Hg in tetrahydrofuran yields (C5H5)3Eu( thf ), and (C5H5)2Eu is not isolated by using an excess of metal. Oxidation of (C5H5)2Eu to (C5H5)3Eu is effected by (C5H5)2Hg in tetrahydrofuran but not by T1(C5H5) in 1,2-dimethoxyethane. Europium and ytterbium react with bis(pentafluoropheny1)mercury and cyclopentadiene in pyridine to give (C5H5)3M( py ) (M = Eu or Yb ).