Ethane analogs

For the purpose of this review, the compounds considered are distributed among the following sections 1,1,l-trichloro-2,2-bis(p-fluorophenyl)-ethane, analogs of 1,1,1-trichloro-2,2-bis(p-fluorophenyl)-ethane, and miscellaneous organofluorine compounds. The chemistry, insecticidal activity, and toxicity of these groups of compounds are considered in the order given. Much of the work in synthetic insecticides, especially the biological portion, is necessarily of an exploratory character, and hence will have to be supported before appraisals become final. 

The prefix thioxo- is used for naming =S in a thioketone. Sulfur analogs of acetals are named as alkylthio- or arylthio-. For example, CH3CH(SCH3)OCH3 is l-methoxy-l-(methylthio)ethane. Prefix forms for -carbothioic acids are hydroxy(thiocarbonyl)- when referring to the O-substituted acid and mercapto(carbonyl)- for the S-substituted acid. 

In the presence of catalysts, trichloroethylene is readily chlorinated to pentachloro- and hexachloroethane. Bromination yields l,2-dibromo-l,l,2-trichloroethane [13749-38-7]. The analogous iodine derivative has not been reported. Fluorination with hydrogen fluoride in the presence of antimony trifluoride produces 2-chloro-l,l,l-trifluoroethane [75-88-7] (8). Elemental fluorine gives a mixture of chlorofluoro derivatives of ethane, ethylene, and butane. 

An analogous series of hydrocarbons, and one of the simplest, are the compounds known as the alkanes. In this series, the names of all the compounds end in -ane. The first compound in this series is methane. Methane s molecular formula is CH. Methane is a gas and is the principal ingredient in the mixture of gases known as natural gas. The next compound is this series is ethane, whose molecular formula is CjHj. It is also a gas present in natural gas, although in a much lower percentage than methane. The difference in the molecular formulas of methane and ethane is one carbon and two hydrogen atoms. 

Analogy between the Delocalized Orbitals of a Hydrocarbon Skeleton (Ethylene, Ethane, Allene, Propane, etc.) and the T Delocalized Orbitals of Conjugated Chains... 

The polarization of biphenyl, deserves special comment. If, as indicated in Scheme 2, its immediate precursor is a radical pair consisting of two phenyl radicals, then it should be formed without detectable net polarization since if Ag = 0. Analogous results have been reported in the decomposition of other peroxides for example, ethane formed from acetyl peroxide shows net emission. To account for this, it has been suggested (Kaptein, 1971b, 1972b Kaptein et al., 1972) that nuclear spm selection which occurs in the primary radical pair—in... 

Treatment of aromatic aldehydes such as p-anisaldehyde with Zn-powder and l,2-bis(chlorodimethylsilyl)ethane 45 give Zn-carbene adducts such as 2096 which add readily to olefins such as cyclohexene [22, 26] or styrene [26] to give high yields of cyclopropanes such as 2097 and the oxide 47 [26]. Acetals such as 2098 react analogously with cyclohexene to afford the endo and exo cyclopropanes 2099 and 2100 [22, 27] (Scheme 13.11). 

Because ethyl radicals have been observed in the preceding experiment, which also suggest that these radicals are stable at 50 K, the initial formation of ethyl radicals would undoubtedly lead to the observation of the radicals. A possible mechanism may be proposed by analogy to molecular organometallic chemistry. Negishi et al. have shown that the reaction of zir-conocene dichloride with AlEts hberates ethane and forms a coordinated ethylene according to [129] ... 

Table II. Synopsis of Laboratory Methods Used to Prepare Analogs of 1,1,1 -Trichloro-2,2-bis(p-fluorophenyl)-ethane Having Insecticidal Interest...

A need has arisen for a sensitive and specific method of estimating microgram quantities of the insecticide methoxychlor in plant and animal products.. Methoxychlor, l,l,l-trichloro-2,2-bis(p-methoxyphenyl)-ethane, is an analog of DDT and therefore procedures for the determination of DDT should be applicable to methoxychlor as well. Such has actually been found to be the case. 

In this section, we present a unified picture of the different electronic effects that combine to determine methyl rotor potentials in the S0, Sp and D0 electronic states of different substituted toluenes. Our approach is based on analysis of ab initio wavefunctions using the natural bond orbitals (NBOs)33 of Weinhold and cowork-ers. We will attempt to decompose the methyl torsional potential into two dominant contributions. The first is repulsive steric interactions, which are important only when an ortho substituent is present. The second is attractive donor-acceptor interactions between CH bond pairs and empty antibonding orbitals vicinal to the CH bonds. In the NBO basis, these attractive interactions dominate the barrier in ethane (1025 cm-1) and in 2-methylpropene (1010 cm-1) see Figure 3. By analogy, donor-acceptor attractions are important in toluenes whenever there is a substantial difference in bond order between the two ring CC bonds adjacent to the C-CH3 bond. Viewed the other way around, we can use the measured methyl rotor potential as a sensitive probe of local ring geometry. 

The low temperature carbonylation of (i7-C4H6)2Ti(dmpe) [dmpe = l,2-bis(dimethylphosphino)ethane] resulted in the formation of Ti(CO)3(dmpe)2 (4) in 55% yield. Complex 4 along with its depe analog 5 [depe = l,2-bis(diethylphosphino)ethane] could also be prepared via the... 

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