1- ethyl chlorides, 2-substituted

In the second, which belongs to a systematic study of the transmission of substituent effects in heterocyclic systems, Noyce and Forsyth (384-386) showed that for thiazole, as for other simple heterocyclic systems, the rate of solvolysis of substituted hetero-arylethyl chlorides in 80% ethanol could be correlated with a constants of the substituent X only when there is mutual conjugation between X and the reaction center. In the case of thiazole this situation corresponds to l-(2-X-5-thiazolyl)ethyl chlorides (262) and l-(5-X-2-thiazolyl)ethyl chlorides (263). 

Methane, chlorine, and recycled chloromethanes are fed to a tubular reactor at a reactor temperature of 490—530°C to yield all four chlorinated methane derivatives (14). Similarly, chlorination of ethane produces ethyl chloride and higher chlorinated ethanes. The process is employed commercially to produce l,l,l-trichloroethane. l,l,l-Trichloroethane is also produced via chlorination of 1,1-dichloroethane with l,l,2-trichloroethane as a coproduct (15). Hexachlorocyclopentadiene is formed by a complex series of chlorination, cyclization, and dechlorination reactions. First, substitutive chlorination of pentanes is carried out by either photochemical or thermal methods to give a product with 6—7 atoms of chlorine per mole of pentane. The polychloropentane product mixed with excess chlorine is then passed through a porous bed of Fuller s earth or silica at 350—500°C to give hexachlorocyclopentadiene. Cyclopentadiene is another possible feedstock for the production of hexachlorocyclopentadiene. 

Many different catalysts are available for this reaction. AlCls-EiCl is commonly used. Ethyl chloride may be substituted for EiCI in a mole-for-mole basis. Typical reaction conditions for the liquid-phase AICI3 catalyzed process are 40-100°C and 2-8 atmospheres. Diethylbenzene and higher alkylated benzenes also form. They are recycled and dealky-lated to EB. 

This procedure illustrates a process which is general for 1,1-diphenyl substituted hydrocarbons. Diphenylmethane has been alkylated3 with benzyl chloride, benzhydryl chloride, a-phenyl-ethyl chloride, /3-phenylethyl chloride, isopropyl chloride, 2-ethylbutyl bromide, and re-octyl bromide in yields of 99, 96, 97, 88, 86, 96, and 99%, respectively. 

Saalfrank, Hoffmann and co-workers performed a number of reactions with tetra-alkoxyallenes such as 196 (Scheme 8.47) [1, 41, 105, 114—116] and demonstrated that this class of donor-substituted allenes can serve as a 1,3-dianion equivalent of malonic acid. Treatment of 196 with cyclopropyldicarboxylic acid dichloride 197 produces 2,4-dioxo-3,4-dihydro-2H-pyran 198 through release of two molecules of ethyl chloride [115]. Similarily, the reaction of this allene 196 with oxalyl chloride gives 3-chloromalonic acid anhydride derivative 199. This intermediate is a reactive dieno-phile which accepts 2,3-dimethyl-l,3-butadiene in a subsequent [4+2] cycloaddition to afford cycloadduct 200 in good yield [116]. 

Secondary hydrogen kinetic isotope effects are further classified as alpha, beta, etc. depending on the distance of the isotopically substituted atom from the bond(s) that is (are) being made or broken (a = 1 bond, 3 = 2 bonds, etc.). Consider the simple Sn2 reaction between hypochlorite anion and ethyl chloride ... 

Acetyl chloride must always be stored under anhydrous conditions, because it readily reacts with moisture and becomes hydrolysed to acetic acid. On the other hand, if one wanted to convert ethyl chloride into ethanol, this nucleophilic substitution reaction would require hydroxide, with its negative charge a better nucleophile than water, and an elevated temperature (see Section 6.3.2). It is clear, therefore, that the carbonyl group is responsible for the increased reactivity, and we must implicate... 

Ethylhydroxyethylcellulose (EHEC) is a nonionic mixed ether available in a wide variety of substitutions with corresponding variations in aqueous and organic liquid solubilities. It is compatible with many oils, resins, and plasticizers along with other polymers such as nitrocellulose. EHEC is synthesized through a two-step process beginning with the formation of the HEC-like product through reaction between the basic cellulose and ethylene oxide. The second step involves further reaction with ethyl chloride. 

Meanwhile, extensive investigation of other of the many reactions by which tetraethyllead can be synthesized, such as the substitution of magnesium and other alkylating metals for sodium and of other ethyl esters for ethyl chloride, has led to the conclusion that none of these is likely to replace the lead-sodium-ethyl chloride method in the foreseeable future. Further reduction in cost would appear most likely to come from refinements in the existing process, and further reduction in operating hazards. One important factor in the cost is not susceptible to improvement by research—the cost of pig lead, which today represents about 18% of the selling price of tetraethyllead as motor fluid. The present price of pig lead is about three times that during most of the past 25 years. 

Electrophilic replacement constants crXr have been obtained for all the positions of benzo[6]thiophene from the solvolysis of isomeric l-(benzo[ >]thienyl)ethyl chlorides in 80% ethanol-water. These constants signify replacement of the entire benzene ring by another aromatic system (74JOC2828). The positional order of reactivity was determined to be 3>2>6>5>4>7, all positions being more reactive than benzene. The same order was also derived from the kinetic data for pyrolysis of the isomeric l-(benzo[6]thienyl)ethyl acetates (78JCS(P2)1053). A modified extended selectivity treatment has been developed to correlate electrophilic substitution data in benzo[Z> ]thiophene, which assumes a dual activation mechanism (79JOC724). 

The rates of solvolyses of l-(2-substituted 4-thiazolyl) ethyl chlorides (44) do not, however, correlate with crm.326 There is nevertheless a correlation with reactivities for 6-substituted 2-pyridyl68 systems, which also contain the reaction site and substituents flanking the N. Analysis of the results in terms of the multiparameter Eqs. (1) and (3) reveals the predominance of resonance effects. The same conclusions apply to the... 

Chlorinated Paraffins. Cl will displace one, two, three, or more hydrogens from the paraffins. These substitution products are referred to as mono (C H2 tiCI), dr (C H Cb). iri (C H2 .>CIi). and so on. Monochloro derivatives include methyl chloride. CHvCI. ethyl chloride. CjHjCI. and propyl chloride. C3H7CI. These are also called alkyl chlorides. Examples of dichlom compounds include methylene dichloride. CHiCL. and ethylene dichloridc, C3H.1CI1 Chloroform. CHCl.v, and... 

When a hydrocarbon is substituted with other than alkyl groups a new problem arises, which can be illustrated by CH3CH2C1. This substance can be called either chloroethane or ethyl chloride, and both names are used in conversation and in print almost interchangeably. In the IUPAC system, halogens, nitro groups, and a few other monovalent groups are considered to be substituent groups on hydrocarbons and are named as haloalkanes, nitro-alkanes, and so on. 

Wheland (1960) made the point in several ways that these principles could lead to absurd errors. When ethyl chloride is treated with hydroxide ion, we obtain ethanol, not dimethyl ether but when iso-bornyl chloride is treated in the same way we obtain camphene after a deep-seated skeletal rearrangement. Although nucleophilic substitution at an ethylenic center goes with retention (Miller and Yonan, 1957), the Walden inversion undercuts any general principle of minimum configurational change. Likewise, an early PLM representation of the... 

Grease-proof pulp, a bleached sulfite pulp from spruce, with high hemi-cellulose content, from Billerud-Uddeholm AB, Saffle, Sweden. Ethyl cellulose, three samples prepared from alkali cellulose and ethyl chloride to low degrees of substitution (DS) about 0.25, 0.4 and 0.6 ethyl ether groups per glucose unit. 

Evidently, the approximately linear Taft correlation obtained for the elimination of / -substituted primary chlorides6 suggested an examination of a possible linear free-energy relationship for aliphatic secondary alkyl chlorides pyrolyses, that is, for a-substituted ethyl chlorides ZCH(C1)CH370 (Table 6). 

With respect to a-substituents bearing p- or 7r-electrons which are directly attached to the C—Cl bond (Table 6, Z = CH2=CH to CH3CH20), these may delocalize their electrons through resonance or mesomeric effects with the positively charged carbon atom in the transition state. Because of this, they were not plotted in the Taft figure for a-substituted ethyl chlorides. Furthermore, the rates for these substituents also could not be correlated with the electrophilic substituent constants a+. The o+ parameters have been defined for substituents on the benzene ring which are far from the reaction site. Even though steric effects may interfere with the coplanarity and hence with delocalization, the effect of these substituents was believed to be polar in nature. 

CH3CO to Cl), a plot of their log kTel versus inflection point of the line at approximate straight line with p = 0.13 and r = 0.912 at 300 °C. Again, this figure resembles the Taft slope found in the gas-phase elimination of HC1 of a- and -substituted ethyl chlorides 62,70, and the small alteration in... 

This conclusion is demonstrated by the fact that for primary alkyl chlorides, an added CH3 group at the /1-carbon of ethyl chloride, i.e. propyl chloride, increases the rate 8.1-fold faster than ethyl chloride, while 3-chloropropionitrile of nearly equal chain length is significantly slower in rate. Moreover, on replacement of the /1-hydrogen in rc-propyl chloride by CH3 and CN as shown above, the /1-CN exerts a deactivating effect. Similar observations apply for -substituted propyl chloride, and for the secondary and tertiary alkyl chlorides. These values demonstrate again the polar nature of the transition state where the C—Cl bond is polarized as in C - -C 5. ... 

An additional example of neighboring group participation in the gas-phase pyrolysis of 2-substituted ethyl chlorides was the elimination kinetics of 2-dimethylaminoethyl chloride67. The magnitude of the effect of Me2N on the dehydrochlorination rate (Table 14) led to a similar consideration to that for CH3SCH2CH2C1 by assuming the transition state for the elimination as an intimate ion-pair as represented above. 

Examination of the first six entries in the table reveals an interesting trend. Methyl chloride reacts significantly faster than ethyl chloride. The other primary chlorides, propyl chloride and butyl chloride, react at nearly the same rate as ethyl chloride. However, isopropyl chloride reacts 40 times more slowly than ethyl chloride, and /erf-butyl chloride, for all practical purposes, does not undergo the SN2 reaction at all. (When forced, terf-butyl chloride will give a substitution product, but the reaction follows a different mechanism, as we will see shortly.)... 

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