Room temperature and below

At room temperature and below, in fast flow systems, the additional reactions are those of H atoms with HO2 

Reactions (viii) and (viiia) are in turn followed by further reactions of OH and O. When M = Ar or He, these further reactions are principally 

however, molecular hydrogen is present in sufficient quantity, reaction 

These subsequent reactions of OH and O are all sufficiently fast that [O] and [OH] never become comparable with [H]. Reactions (xxi) and (xxii) of OH and O with HO do not therefore become important in these room temperature systems where the initial radical is the H atom. Reactions (viii) and (xx) are also sufficiently fast that [HOj ] never becomes large enough for reaction (x) to need consideration. 

Clyne and Thrush indeed found the ratio [H2O] formed/[H] used to increase in mixtures containing more molecular hydrogen. In their experiments using Ar or He containing 1 % H2 initially, the amount of molecular hydrogen remaining after the discharge is small. In these cases 

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Tertiary alcohols are converted to alkyl chlorides m high yield within minutes on reaction with hydrogen chloride at room temperature and below... 

The products of these reactions are called vicinal dihalides Two substituents m this case the halogens are vicinal if they are attached to adjacent carbons The word is derived from the Latin vicinalis which means neighboring The halogen is either chlorine (CI2) or bromine (Br2) and addition takes place rapidly at room temperature and below m a variety of solvents mcludmg acetic acid carbon tetrachloride chloroform and dichloromethane... 

Polycarbonates are an unusual and extremely useful class of polymers. The vast majority of polycarbonates are based on bisphenol A [80-05-7] (BPA) and sold under the trade names Lexan (GE), Makrolon (Bayer), CaUbre (Dow), and Panlite (Idemitsu). BPA polycarbonates [25037-45-0] having glass-transition temperatures in the range of 145—155°C, are widely regarded for optical clarity and exceptional impact resistance and ductiUty at room temperature and below. Other properties, such as modulus, dielectric strength, or tensile strength are comparable to other amorphous thermoplastics at similar temperatures below their respective glass-transition temperatures, T. Whereas below their Ts most amorphous polymers are stiff and britde, polycarbonates retain their ductiUty. 

Although alkenes typically react with chlorine and bromine by addition at room temperature and below (Section 6.14), substitution becomes competitive at higher temperatures, especially when the concentration of the halogen is low. When substitution does occur, it is highly selective for the allylic position. This forms the basis of an industrial preparation of allyl chloride ... 

The X-ray measurements at 1.5, 13, and 30° do, in fact, show a large concentration of molecules at about 4.5 angstroms. This is strong evidence in favor of widespread local tetrahedral arrangement in water at room temperature and below. 

The first widely used intermediates for nucleophilic aromatic substitution were the aryl diazonium salts. Aryl diazonium ions are usually prepared by reaction of an aniline with nitrous acid, which is generated in situ from a nitrite salt.81 Unlike aliphatic diazonium ions, which decompose very rapidly to molecular nitrogen and a carbocation (see Part A, Section 4.1.5), aryl diazonium ions are stable enough to exist in solution at room temperature and below. They can also be isolated as salts with nonnucleophilic anions, such as tetrafluoroborate or trifluoroacetate.82 Salts prepared with 0-benzenedisulfonimidate also appear to have potential for synthetic application.83... 

G.E. Childs, L.J. Ericks, R.L. Powell Thermal conductivity of solid at room temperature and below, NBS Monograph 131 U. S. Govt. Printing Office, Washington, DC (1973)... 

The CO oxidation reaction occurs rapidly at room temperature and below. As an example, on a Au(lll) surface at 250 K with onear unity exposed to a constant CO pressure of Pco = 2 x 10 Torr, the reaction rate expressed as turn-over frequency (TOF [molecules CO2 (Au atom s)" )/ is approximately 2.5 x 10-3 immediately after the reaction has been initiated and then declines at a relatively constant rate reaching a value of 3 x 10" after the reaction has proceeded approximately 800 seconds. Reaction order... 

We do not need to regard YBa2Cus07 as a solid solution, but it is not a thermodynamically stable phase at any temperature/pressure condition (11). Thermodynamic stability exists in the YBa2Cus06+x system in a certain region of temperature and oxygen pressure, but only for values of x between zero and about 0.6. Even these compositions appear not to be thermodynamically stable at room temperature and below. 

There are two possible exceptions to the rule that high Tc superconductors are metastable. Both YBa2Cu4Og and Y2Ba4Cu7015 appear to be stable under the conditions where they form, and they are superconductors without further oxidation. The remaining question to be answered is whether or not they are thermodynamically stable at room temperature and below. This is a difficult question to answer. Calorimetry can compare the heats of formation of these compounds with other compounds known in the Y/Ba/Cu/O system. However, it is always possible that some of the most stable phases in the Y/Ba/Cu/O system have not yet been prepared because they are kinetically inaccessible. 

Related alkylrhenium(VI) complexes can be transformed to the same active species [MeRe0(02)2 H20] in the presence of hydrogen peroxide and therefore can also serve as catalysts. A comparison of the catalytic activity of various rhenium compounds is given in Reference 345. Because of its great oxidation activity, MTO can be used at room temperature and below. Although MTO is more active in the absence of bases like... 

The subsequent evaluation of rate constants33,38 has shown that k66 is three times as large as k 63 at room temperature if Ar is the chaperone for reaction (3-63). If Cl2 is the principal chaperone, and if it is not more than three times as efficient as Ar, then reaction (3-63) is not in equilibrium at room temperature and below eq. (3-1 ) must be used. Of course if another gas is the principal chaperone gas or if Cl2 is much more efficient than Ar as a chaperone, then reaction (3-63) is in equilibrium above room temperature, and eq. (3-T) reduces to eq. (3-1). The experiments of Burns and Dainton33 exhibited a slight falloff for (CC120) at high [Cl2] as predicted from eq. (3-1). Thus the indications are that eq. (3-T) must be used, that Cl2 is not unusually efficient in reaction (3-63), and thus that there is no evidence for a Cl3 intermediate. 

To calculate the probability of electron tunneling using eqn. (18) it is necessary to know the wave functions F(q) describing the nuclear motion. At room temperature and below, it is possible to consider only the harmonic vibrations of the atoms near the equilibrium positions. Such vibrations are present even in liquids for comparatively long periods of time during which... 

The functional group which produces the observed band, The multiplicity of the band is indicated in parenthesis s = singlet m = complex multiples Primary reference standard for room temperature and below. 

Baker and Bobonich5) have taken X-ray powder photographs of I and II at room temperature and below Tc. They found no structural change on cooling and thus... 

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