Hydrogen chloride dimer

The mPBE functional39 is a modification of the nonempirical PBE functional into which one empirical parameter was reintroduced. Compared to PBE, mPBE leads to significantly worse interaction energy for the water dimer, whereas the interaction energies in the cases of hydrogen fluoride and hydrogen chloride dimers are only slightly improved. 

Cope, R, Legon, A. C., and Millen, D. J., The microwave spectrum and geometry of the methanol-hydrogen chloride dimer, Chem. Phys. Lett. 112, 59-64 (1984). 

Karpfen, A., Bunker, P. R., and Jensen, P., An ab initio study of the hydrogen chloride dimer the potential energy surface and the characterization of the stationary points, Chem. Phys. 149, 299-309(1991). 

Magnesium/hydrogen chloride Dimeric tert. alcohols from ketones... 

Chromous sulfate/perchloric acid hydrogen chloride Dimerization... 

The entropy value of gaseous HCl is a sum of contributions from the various transitions summarized in Table 4. Independent calculations based on the spectroscopic data of H Cl and H Cl separately, show the entropy of HCl at 298 K to be 186.686 and 187.372 J/(mol K) (44.619 and 44.783 cal/(mol K), respectively. The low temperature (rhombic) phase is ferroelectric (6). SoHd hydrogen chloride consists of hydrogen-bonded molecular crystals consisting of zigzag chains having an angle of 93.5° (6). Proton nmr studies at low temperatures have also shown the existence of a dimer (HC1)2 (7). 

The properties of 1,1-dichloroethane are Hsted ia Table 1. 1,1-Dichloroethane decomposes at 356—453°C by a homogeneous first-order dehydrochlofination, giving vinyl chloride and hydrogen chloride (1,2). Dehydrochlofination can also occur on activated alumina (3,4), magnesium sulfate, or potassium carbonate (5). Dehydrochlofination ia the presence of anhydrous aluminum chloride (6) proceeds readily. The 48-h accelerated oxidation test with 1,1-dichloroethane at reflux temperatures gives a 0.025% yield of hydrogen chloride as compared to 0.4% HCl for trichloroethylene and 0.6% HCl for tetrachloroethylene. Reaction with an amine gives low yields of chloride ion and the dimer 2,3-dichlorobutane, CH CHCICHCICH. 2-Methyl-l,3-dioxaindan [14046-39-0] can be prepared by a reaction of catechol [120-80-9] with 1,1-dichloroethane (7). 

At higher temperatures under nitrogen, the polymer is reduced to coke with the evolution of hydrogen chloride and organic Hquids such as chloroprene dimer. At temperatures below 275°C, polymers prepared at low temperature, with less 1,2- and 3,4-addition, are less reactive. Dehydrochlorination under nitrogen is not a radical chain process below about 275°C (105). 

The synthesis of thiepins 14 was unsuccessful in the case of R1 = i-Pr,79 but if the substituents in the ortho positions to sulfur arc /erf-butyl, then thiepin 14 (R1 = t-Bu R2 = Me) can be isolated in 99% yield.80 Rearrangement of diazo compound 13 (R1 = t-Bu R2 = H), which does not contain the methyl group in position 4, catalyzed by dimeric ( y3-allyl)chloropalladium gives, however, the corresponding e.w-methylene compound. The thiepin 14 (R1 = t-Bu, R2 = H) can be obtained in low yield (13 %) by treatment of the diazo compound with anhydrous hydrogen chloride in diethyl ether at — 20 C.13 In contrast, the ethyl thiepin-3,5-or -4,5-dicarboxylates can be prepared by the palladium catalysis method in satisfying yields.81... 

Fig. 3. Stereoview of the inclusion complex between a hydrogen-bonded dimer of host 3 with water and methylene chloride as guests. The crystal structure of this compound contains two additional species, a disordered CH Clj and fractional water (donated by S ). Both lie outside the complex between the bound water and an adjacent host unit (taken from Ref.28>)...

The chemical behavior of the cyclic dimer is quite analogous to that of other uretidine diones (69). Some characteristic reactions are summarized in Table III. As can be seen in Table III the mechanism of the reactions with ammonia and hydrogen chloride is not quite clear. The isolated products can be obtained either via a uretidine-dione or via a linear intermediate. 

Methoxy-6-propyl-l,4-benzoquinone (170, Scheme 43) with hydrogen chloride undergoes dimerization and yields the biquinone 171 and the di-benzofuran 172. 2-Hydroxy-3,6-dimethyl-1,4-benzoquinone (173, Scheme 44), however, on treatment with boron trifluoride etherate in ether, or with concentrated sulfuric acid in acetic acid at room temperature, yields the extended quinone 174, which on reductive acetylation affords the dibenzo-furan 175. 

At low concentrations of chlorine, dimeric nitrosoalkanes free from chlorine are produced when alkanes are treated also with nitric oxide. Under these circumstances, molecular chlorine is first converted into atomic chlorine which attacks the alkane to form alkyl radicals and hydrogen chloride. The alkyl radicals, in turn, form nitrosoalkanes with nitric oxide. This reaction is most effectively carried out when the ultraviolet radiation is between 380 and 420 mp. [43, 56],... 

Interestingly, 138 with ethenesulfonic acid, 283 (R = OH) [unlike acid derivatives (283 R = O-alkyl, NRj) which yield crystalline Diels-Alder adducts (284) (Table VI)] gives an adduct which on treatment with hydrogen chloride or ethanol yields 1,4-diphenylnaphthalene (285) and a dimer of 138 (286 mp 236 C) (Scheme 18). The mechanism for the generation of 286 is not known. 

The compounds resulting from the reaction of 748 were characterized by HRMS directly coupled to the reactor. The stable products 750 and 751 were analysed by GC and 111 NMR spectroscopy. The formation of the cyclodisilazane 750 is explained by dimerization of the unstable silanimine 749 only in the cold trap, as the reaction is carried out under high dilution conditions (equation 247). It was also shown that the hydrogen chloride elimination did not occur in the ion source of the mass spectrometer. 

Coupling of n- allylic)paUadium complexes with an alkenylzirconium(IV) complex l,4-< enes.2 A recent stereospecific synthesis of natural (20R)-cholestanone-3 (4) involves coupling of the alkenylzirconium complex 2 with the jr-(allylic)palladium chloride dimer (1) of a (Z)-17(2U)-pregnene. The major product is a 1,4-diene (3), formed by regioselective attack of 2 at C20, the less hindered terminus of the allylic unit, and with inversion at C20. Coupling of 2 with the 7i-(allylic)palladium chloride dimer of the (E)-isomer of 1 results in a 1,4-diene epimeric at C20 with 3. Hydrogenation of the diene completes the synthesis of the desired natural cholestanone-3 (4). 

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