Aluminum compounds chemical behaviors

The chemical behavior of tetraalkylstannanes is radically different from that of the far more reactive aluminum alkyls. The tin compounds are stable in air, they do not react with water, and they do not... 

On treatment with concentrated hydrochloric acid and aluminum amalgam, l-telluracyclohexane-3,5-diones decompose with elimination of tellurium. Their chemical behavior is determined by the presence of the dicoordinate tellurium center and two carbonyl groups in their molecules. As cyclic diketones, compounds 12 readily form oximes and dioximes under treatment with hydroxylamine. The former reaction is preferably carried out in dilute acetic acid solution, whereas the latter is carried out in basic... 

Now that we are able to understand the chemical behavior of many main-group elements such as lithium, silicon, boron, and aluminum, the purpose of this book is to summarize these recent developments and show the promising future roles of complexes of these metals in modern organic synthesis. In fact, these reagents are both useful and much safer than most transition-metal compounds. 

This review article is concerned with chemical behavior of organo-lithium, -aluminum and -zinc compounds in initiation reactions of diolefins, polar vinyls and oxirane compounds. Discussions are given with respect to the following five topics 1) lithium alkylamide as initiator for polymerizations of isoprene and 1,4-divinylbenzene 2) initiation of N-carboxy-a-aminoacid anhydride(NCA) by a primary amino group 3) activated aluminum alkyl and zinc alkyl 4) initiation of stereospecific polymerization of methyloxirane and 5) comparison of stereospecific polymerization of methyloxirane with Ziegler-Natta polymerization. A comprehensive interpretation is proposed for chemistry of reactivity and/or stereospecificity of organometallic compounds in ionic polymerizations. 

This review article is concerned with chemical behavior of organo-lithium, -aluminum and -zinc compounds in initiation reactions of diolefins, polar vinyls and oxirane compounds. A comprehensive interpretation is proposed for metallic compounds in ionic polymerizations. 

Looking down Group 3A(13), we see a wide range of chemical behavior. Boron, the first metalloid we ve encountered, is much less reactive at room temperature than the other members and forms covalent bonds exclusively. Although aluminum acts physically like a metal, its halides exist in the gas phase as covalent dimers— molecules formed by joining two identical smaller molecules (Figure 14.4)—and its oxide is amphoteric rather than basic. Most of the other 3A compounds are ionic, but with more covalent character than similar 2A compounds because the 3A cations can polarize nearby electron clouds more effectively. 

Other compounds such as aluminum trihydrate and silicate compounds have also been tried as fire retardants for wood. These compounds work best in combination with other chemicals, especially those in which the behavior is synergistic. 

Some acids (e.g., acetic and citric) have a sour taste. In fact, sourness had been a defining property since the 17 " century an acid was any substance that had a sour taste reacted with active metals, such as aluminum and zinc, to produce hydrogen gas and turned certain organic compounds characteristic colors. (We discuss indicators later and in Chapter 19.) A base was any substance that had a bitter taste and slippery feel and turned the same organic compounds different characteristic colors. (Please remember NEVER to taste or touch laboratory chemicals instead, try some acetic acid in the form of vinegar on your next salad.) Moreover, it was known that when acids and bases react, each cancels the properties of the other in a process called neutralization. But definitions in science evolve because, as descriptions become too limited, they must be replaced by broader ones. Although the early definitions of acids and bases described distinctive properties, they inevitably gave way to definitions based on molecular behavior. 

The metallurgical characteristics of the aluminum oxide layer also depend on its physical metallurgy, such as defects and metallurgical structure included in the oxide layer. For instance, when intermetallic compound particles as secondary phases are exposed on the surface, a discontinuous oxide film with various defects is often produced at the metal-particle interface. This discontinuous oxide film is weakly or non-protective chemically and physically. Because corrosion is a chemical and electrochemical reaction on the surface, corrosion behavior is readily influenced by surface morphology. The aluminum surface is usually adsorbed or contaminated by water, gases and many kinds of micron-sized substances. Microscopic heterogeneous structures such as vacancies, steps, kinks, and dislocations, and macroscopic heterogeneous structures such as scratches, pits and other superficial blemishes influence the corrosion behavior of aluminum and its alloys to different extents. 

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