Cyclohexane cyclopropane

The proton affinities of alicyclic carboxylic acids are identical within 5 kj mol-1, with cyclohexane >cyclopropane >cyclopentane >cyclobutane [205]. This quite surprising situation seems not to be fully explained yet. 

Butyl-1-propyl- V/la, 35f. Heptyl-E19a, 535 (En -t- Cyclohexan) Cyclopropan Decyl- E17a, 272... 

The strain energy of cyclopropane makes it more reactive than cyclohexane. Cyclopropane reacts with hydrogen at 80°C, in the presence of a catalyst (finely divided platinum) ... 

Whatever the explanation, there is no doubt that different zeolites even at the same relative aluminum and silicon contents have dramatically different relative rates of isomerization and hydrogen transfer (43). Using the reaction of cyclohexene to form either cyclohexane, cyclopropane, or cyclopropene the relative rates of isomerization for three different zeolite structures were measured for samples prepared at the same Si/Al ratio 12. The results showed significant differences of nearly an order of magnitude in the relative rates of isomerization to hydrogen transfer. The structural details that provide these differences remain elusive. 

CHj,=CH-CHj Cyclohexane Cyclopropane Cyclobutane Cyclopentane Cyclohexene, CjHnj Dicyclohexyl, CjHn-CjHu Cyclohexadiene N=N... 

Disubstituted cyclopropanes exemplify one of the simplest cases involving stabil ity differences between stereoisomers A three membered ring has no conformational mobility so the ring cannot therefore reduce the van der Waals strain between cis sub stituents on adjacent carbons without introducing other strain The situation is different m disubstituted derivatives of cyclohexane... 

Chiral Alcohols and Lactones. HLAT) has been widely used for stereoselective oxidations of a variety of prochiral diols to lactones on a preparative scale. In most cases pro-(3) hydroxyl is oxidized irrespective of the substituents. The method is apphcable among others to tit-1,2-bis(hydroxymethyl) derivatives of cyclopropane, cyclobutane, cyclohexane, and cyclohexene. Resulting y-lactones are isolated in 68—90% yields and of 100% (164,165). 

Incorporation of stereogenic centers into cyclic structures produces special stereochemical circumstances. Except in the case of cyclopropane, the lowest-eneigy conformation of the tings is not planar. Most cyclohexane derivatives adopt a chair conformation. For example, the two conformers of cis-l,2-dimethylcyclohexane are both chiral. However, the two conformers are enantiomeric so the conformational change leads to racemization. Because the barrier to this conformational change is low (lOkcal/mol), the two enantiomers arc rapidly interconverted. 

NBS can also be used to brominate alkanes. For example, cyclopropane, cyclopentane, and cyclohexane give the corresponding bromides when irradiated in a solution of NBS in dichloromethane. Under these conditions, the succinimidyl radical appears to be involved as the hydrogen-abstracting intermediate ... 

Thus the unsaturated ketones carvone, eucarvone and 1-acetyl-cyclohexane formed the cyclopropyl ketones (6), (7) and (8) while benzalaceto-phenone (9) affords l-benzyl-2-pheny 1-cyclopropane as a mixture of as and irons isomers (10) and (H) 233,234... 

In keeping with the "bent-bond" description of Figure 3.10, the carbon-carbon bond distance in cyclopropane (151 pm) is slightly shorter than that of ethane (153 pm) and cyclohexane (154 pm). The calculated values from molecular models (see Learning By Modeling) reproduce these experimental values. 

Identify the lowest-energy conformer from among those provided cyclopropane, planar and puckered cyclobutane, planar and puckered cyclopentane and chair, half-chair, boat and twist-boat cyclohexane. (If... 

Physical properties of cycloalkanes [49, p. 284 50, p. 31] show reasonably gradual changes, but unlike most homologous series, different members exhibit different degrees of chemical reactivity. For example, cyclohexane is the least reactive member in this family, whereas both cyclopropane and cyclobutane are more reactive than cyclopentane. Thus, hydrocarbons containing cyclopentane and cyclohexane rings are quite abundant in nature. 

The data in Figure 4.3 show that Baeyer s theory is only partially correct. Cyclopropane and cyclobutane are indeed strained, just as predicted, but cyclopentane is more strained than predicted, and cyclohexane is strain-free. Cycloalkanes of intermediate size have only modest strain, and rings of 14 carbons or more are strain-free. Why is Baeyer s theory wrong ... 

Conjugated chains, 14, 46 Correlation diagrams, 44, 50 Cyclobutadiene, 171 Cyclobutane, 47, 222 orbital ordering, 26 through-space interactions, 26 Walsh orbitals, 27 Cyclobutene, 200 Cyclohexane, 278 Cyclohexene (half-boat), 274 Cyclopen tadiene, 225 Cvclopen tadienone, 269 Cyclopentadienyl anion, 237 Cyclopentane, 254 Cyclopen ten e, 241 Cyclopropane, 41, 47, 153 construction of orbitals, 19, 22 Walsh orbitals, 22, 36, 37 Cyclopropanone, 48, 197 bond lengths, 38 Cyclopropen e, 49, 132 reactivity, 40... 

To name an alkane in which the carbon atoms form a single chain, we combine a prefix denoting the number of carbon atoms with the suffix -ane (Table 18.1). For example, CH,—CH, (more simply, CH,CH,) is ethane and CH,—CH2—CH, (that is, CH,CH2CH,) is propane. Cyclopropane, C,H6 (15), and cyclohexane, C6H12 (16), are cycloalkanes, alkanes that contain rings of carbon atoms. 

Curie temperature, 696 cyanide ion, 615 cycles, 4 cycloalkane, 731 cyclohexane, 731 cyclone, 144 cyclopropane, 542, 731 cysteine, 774 cytosine, 438, 777... 

Investigation of Ethane, Propane, Isobutane, Neopentane, Cyclopropane, Cyclopentane, Cyclohexane, Allene, Ethylene, Isobutene, Tetramethylethylene, Mesitylene, and Hexamethylbenzene. Revised Values of Covalent Radii (by Linus Pauling and L. O. Brockway)... 

Fig. 3.—Radial distribution curves for (A) cyclopropane, (B) cyclopentane and (C) cyclohexane.

Cyclopropane, Cyclopentane, and Cyclohexane.—The sample of cyclopropane used was provided by Professor G. S. 

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