Showing papers on "Cyclopropane published in 1967"

Ring location in cyclopropane fatty acid esters by a mass spectrometric method

Abstract: Ring location in cyclopropane fatty acid esters is accomplished simply and unequivocally with submilligram samples. The technique involves reductive ring opening with platinum catalyst and hydrogen in glacial acetic acid, to give a mixture of branched-chain and straight-chain acid esters. The sample is analyzed with a combination gas chrmatograph-mass spectrometer. Examination of the spectra obtained from the mixture of branched-chain acid esters permits assignment of the position of the methyl groups, and hence of the ring in the parent compound.

Cyclopropanecarboxylic acid esters

Abstract: Novel phenyloxy-furylmethyl or -thenyl 2,2-dimethyl 3-substituted cyclopropane carboxylate of the formula:

Binding of Cyclopropane to Sperm Whale Myoglobin

Abstract: THIS article follows reports of the binding of xenon, an anaesthetic agent, to sperm whale met and deoxymyoglobin1,2. X-ray diffraction analysis showed that a single xenon atom binds to the same specific site in both derivatives. This site is located at a cavity in the interior of the molecule, about equidistant from the haem linked histidine and one of the pyrrole rings of the haem group. The difference electron density maps showed that there are no important changes in the structure of myoglobin, an observation which is also supported by the calculated approach distances. It is interesting to note that xenon with a van der Waals radius of 2.20 A seems to be just large enough to fit into this cavity without disturbing the surrounding molecular arrangement. It has been found by spectroscopic analysis that this binding of xenon to myoglobin does not appreciably alter the oxygen affinity of myoglobin. Lumry (personal communication) demonstrated, however, that the carbon monoxide affinity of xenon–myoglobin is increased ten times compared with native myoglobin. It also should be noted that the much larger mercuri–iodide3 binds at the same place, but this time considerably distorting the surroundings. These results led to the present X-ray diffraction analysis of the binding of cyclopropane, which is slightly larger (0.2 A, see Table 2) than xenon, to myoglobin. Crystals of sperm whale met myoglobin prepared by the method of Parrish and Kendrew4 were mounted in quartz capillaries and equilibrated with cyclopropane at a pressure of two atmospheres. X-ray intensities of the hk0 and h0l reflexions were collected to 2.8 A resolution with multiple-film precession photographs. From such data, electron density difference maps between met myoglobin–cyclopropane and the native met myoglobin were calculated using the phase angles for the native structure (unpublished work of Kendrew et al.). Each of these difference electron density maps (Figs, 1a and b) shows a number of features. The positive peak 1 (x= 0.176, y= 0.845, z= 0.187) represents the cyclopropane addition to the molecule and corresponds to the site of the xenon position as found in met and deoxymyoglobin. The negative peak 2 corresponds to the site of a phenylalanine (H14) in the native structure. This negative peak indicates a reorientation of the benzene ring of the phenylalanine group, which is most likely rotated by approximately 90° along the Cα–Cβ bond into a position corresponding to the positive region 3. This reorientation of the phenylalanine ring necessitates some adjustments of neighbouring groups, particularly the two leucines H11 and H13. Possible interference of the displaced phenylalanine with the alanine H10 cannot be ruled out on the basis of the calculated difference maps; it seems, however, unlikely that the H helix would move. Such reorientations are indicated by secondary peaks in the difference maps (Figs, 1a and 1b). It should be noted that cyclopropane is such a light “heavy atom” that secondary sites of less than 35 per cent occupancy would not show up on these difference projections. The calculated approach distances from the centre of peak 1 (cyclopropane site) to the nearest atomic positions as found in the native structure are given in Table 1 and show that a number of approaches are considerably smaller than the sum of the relevant van der Waals radii (Table 2), indicating also reorientation of some amino-acid side chains. Cyclopropane is nearly equidistant from the haem linked histidine and a pyrrole ring of the haem group, groups which do not seem to have moved. Generally, it seems that cyclopropane is bound to myoglobin in the same manner as xenon and is stabilized mainly by London interactions, with some contributions from dipole-induced dipole and charge-induced dipole interactions. There is also an entropy gain, which arises from the cyclopropane transfer into the protein.

Nuclear Magnetic Resanance Spectroscopy. Carbon-Carbon Coupling in Cyclopropane Derivatives

Abstract: The nature of the bonding in cyclopropane, the smallest and most highly strained carbocyclic ring system, has long been a lively and controversial topic. Walsh has described the carbon-carbon bonding in cyclopropane as involving a three-center bond, while Coulson and Moffitt and Trinajstic and have used quantum-mechanical treatments equivalent to bent bonds wherein the regions of highest electron density are not located along the C-C internuclear axes. Molecular orbital calculations of varying degrees of sophistication have been carried outs A recent summary of the description of bonding in cyclopropanes was given by Bernett.

Reactions of cyclic alkyl radicals. Part 2.—Photolysis of cyclopropane carboxaldehyde

Abstract: The vapour-phase photolysis of cyclopropane carboxaldehyde has been studied at various pressures over the temperature range 40–250°C. A major primary process is the intramolecular reaction yielding propylene and carbon monoxide. Cyclopropyl radicals are also produced and isomerize to allyl radicals with an estimated activation energy of about 22 kcal mole–1. A value of 2 has been obtained for the cross-combination ratio for allyl and cyclopropyl radicals.

Reaction of trifluoromethylcarbene with cis- and trans-but-2-enes

Abstract: Trifluoromethylcarbene, generated photolytically from 2,2,2-trifluorodiazoethane, reacts essentially stereo-specifically with trans- and cis-but-2-enes in the liquid phase, to give dimethyltrifluoromethylcyclopropanes, and olefinic insertion products. In the vapour phase, or in solution in an inert solvent, the degree of stereospecificity of the cyclopropane formation and the yield of insertion products are both lower, consistent with the formation of singlet trifluoromethylcarbene and its decay to a triplet state of lower energy. The vapour-phase reaction appears to involve a unimolecular singlet–triplet crossover.

Process for the preparation of chrysanthemic acid

Abstract: CHRYSANTHEMIC ACID, ITS LOWER ALKYL ESTERS AND NITRILE ARE MADE BY DECARBOXYLATING AN ACID OF THE FORMULA: 1-(HOOC-),1-(R-OOC-),2-((CH3-)2-C=CH-),3,3-DI(CH3-)- CYCLOPROPANE OR 1-(HOOC-),1-(NC-),2-((CH3-)2-C=CH-),3,3-DI(CH3-)- CYCLOPROPANE

Some Reactions of Oxygen Atoms. III. Cyclopropane, Cyclobutane, Cyclopentane, and Cyclohexane

Abstract: The rate that oxygen atoms react with certain cycloalkanes was determined at 25°, 70°, and 125°C by the competition for oxygen atoms between a cycloalkane and hexafluoropropene. Oxygen atoms were generated by the mercury‐sensitized decomposition of N2O. Then, the known rate‐constant expression for C3F6 was used to calculate the rate constant for the oxygen atom—cycloalkane reaction. The Arrhenius parameters A and E are as follows: CycloalkaneA×10−9 (liter mole−1·sec−1)E (kcal/mole)cyclo−C3H60.313.8cyclo−C4H86.13.9cyclo−C5H104.82.6cyclo−C6H127.62.8

Photolysis of Cyclopentane at 1470, 1236, and 1048–1067 Å

Abstract: The photolysis of cyclopentane has been investigated at 1470, 1236, and 1048–1067 A. The primary process, cyclo‐C5H10+hv→C5H8+H2 is of major importance at 1470 A, but its quantum yield diminishes at shorter wavelengths where processes involving C–C cleavage become more predominant. The products formed in the gas‐phase photolysis of cyclo‐C5D10—H2S mixtures and in the solid‐phase photolysis of cyclo‐C5H10 indicate that the excited cyclopentane molecule undergoes ring opening to form a 1‐pentene molecule. In the gas phase, the internally excited 1‐pentene decomposes to form methyl and ethyl radicals. Evidence is also obtained for the occurrence of the dissociative process: C5H10*→C2H4+C3H6 where C3H6 consists of cyclopropane and propylene. At 1048–1067 A (11.6–11.8 eV), ionization is extensive (ionization potential of cyclo‐C5H10=10.5 V). Saturation current measurements yielded a value of 0.64 for ηC5H10/ηNO. On the basis of an isotopic analysis of the propane formed in the photoionization of C5D10–C5H10–O2...

Cyclopropanes from αβ-unsaturated esters by the dimethylsulphoxonium methylide reaction

Abstract: Reaction between αβ-unsaturated esters and dimethylsulphoxonium methylide gives cyclopropane-carboxylic esters in good yield. A new and improved method, using NN-dimethylformamide as solvent, is described. The u.v. spectra of cyclopropane esters and ketones are discussed.

Diphenylcyclopropyl-methyl-amines

Abstract: DIPHENYLCYCLOPROPYL-METHYL-AMINES HAVING FAIRLY LOW TOXICITY AND SERVING AS CENTRAL NERVOUS SYSTEM STIMULANTS WITH MARKED ANTI-DEPRESSANT ACTIVITY, REPRESENTED BY THE FORMULA: 1-(R2-N(-R1)-CH2-),2-(X,Y-PHENYL),3-(X1,Y1-PHENYL) CYCLOPROPANE WHEREIN X, Y, X1, Y1 ARE MEMBERS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN, METHYL AND METHOXY; R1 IS A HYDROGEN ATOM OR AN ALKYL RADICAL CONTAINING FROM 1 TO 4 CARBON ATOMS; R2 IS HYDROGEN ATOM OR ALKYL RADICAL CONTAINING FROM 1 TO 4 CARBON ATOMS, DIMETHYLAMINOETHYL, DIMETHYLAMINOPROPYL, METHYLAMINOPROPYL, 2,3-DIPHENYLCYCLOPROPANE-1-METHYL, CYCLOHEXYL RADICALS AND THEIR PHARMACEUTICALLY ACCEPTABLE SALTS WITH ORGANIC AND INORGANIC ACIDS.

Electronic Structures and Reactivities of Aliphatic Small Membered-Ring Compounds. II

Abstract: Extended Huckel MO investigations of the physico-chemical properties of cycloalkanes have been carried out. The calculated total energies of protonated cyclopropane and cyclopentane show that the most stable configuration of protonated cycloalkanes is the one with the conformation in which a proton exists in the ring plane. In cyclopropane, the changes in the total electronic energies and in the charge distributions caused by the protonation are almost the same as those in ethylene, while no remarkable changes in these quantities can be observed in protonated cyclopentane. It may be concluded that cyclopropane has unsaturated properties similar to those of the π-electron system in its ring plane. Further, the reaction mechanism and the reactivities of halogenocycloalkanes in the SN2-type reaction are discussed. It is shown that the theoretical results can successfully explain their chemical reactivities.

Halogenation and olefinic nature of cyclopropane

Abstract: A brief discussion of evidence for the double-bond nature of the cyclopropane ring is presented, followed by a summary of representative studies of cyclopropane halogenations and related reactions.

Substituted anilide carbamates

Abstract: New compounds corresponding to the formula: IN WHICH R1 is hydrogen, lower alkyl, or lower alkenyl; R2 is alkyl, lower alkenyl, cycloalkyl, phenyl or substituted phenyl in which the substituents are lower alkyl, lower alkoxy, nitro or halogen; and R3 is hydrogen, lower alkyl, cycloalkyl having 3 to 4 carbon atoms, inclusive, halogenated lower alkyl, lower alkenyl, furyl or benzyl; provided that when R1 is hydrogen or lower alkyl R3 is other than lower alkyl and further provided that when R1 is hydrogen and R2 is methyl, R3 is other than hydrogen, halogenated lower alkyl, cycloalkyl or lower alkenyl. The above-defined compounds are effective herbicides, particularly for the control of grasses and broadleaf plants with both pre-emergence and post-emergence activity. Representative compounds are: 3''-(N-n,propylcarbamoyloxy)cyclopropane carboxanilide, 3''-(N-n-butylcarbamoyloxy)crotonanilide, 3''-(Nethylcarbamoyloxy)furoyl anilide, 3''-(N,N-diallylcarbamoyloxy) propionanilide, 3''-(N-n-propylcarbamoyloxy)vinylacetanilide and 3''-(N-i-propylcarbamoyloxy)2-bromo isobutyranilide.