Carbon ionic carbides

Carbon forms ionic carbides with the metals of Groups 1 and 2, covalent carbides with nonmetals, and interstitial carbides with d-block metals. Silicon compounds are more reactive than carbon compounds. They can act as Lewis acids. 

Give an example of an ionic carbide. What is the oxidation state of carbon in this substance ... 

The C NMR spectra of the ionic carbides CaC2 and BaC2 have been determined by Wrackmeyer et al. (1990) who report 8iso values of 206.2 ppm for CaC2 and 232.1 ppm for BaC2, both shifts with respect to TMS. The NMR results indicate that the environment of the carbon atoms in these compounds is not axially symmetric, and that the carbide unit in these ionic carbides is not comparable with the carbon-carbon triple bond in alkynes. 

A present-day definition of organic chemistry would be one that includes the study of carbon compounds, and in particular those compounds that possess covalent carbon/carbon and carbon/hydrogen bonds. This definition is very general, and as such there are many exceptions to it. For example, carbonates and carbides are normally considered under the chemistry of the cation with which they are associated. This is because, even though they contain covalent bonds, they are often ionic solids with high melting points, and these are characteristic properties of inorganic compounds. 

What is an organic compound Dictionaries define it as a compound of carbon, but that definition is too general because it includes carbonates, cyanides, carbides, cyanates, and other carbon-containing ionic compounds that most chemists classify as inorganic. Here is a more specific definition all organic compounds contain carbon, nearly always bonded to other carbons and hydrogen, and often to other elements. 

Ionic carbides, which contain the carbide ion C" . An example is aluminum carbide, AI4C3. Compounds of this type react with water to give methane (they were formerly also called methanides). The dicarbides are ionic carbon compounds that contain the dicarbide ion C C". The best-known example is calcium dicarbide, CaC2, also known as calcium carbide, or simply carbide. Compounds of this type give ethyne with water. They were formerly called acetylides or ethynides. Ionic carbides are formed with very electropositive metals. They are crystalline. 

The binary compounds of carbon with metals, metalloids, and certain nonmetals are called carbides. The more active metals form ionic carbides, and the most common of these contain the acetylide ion (C2 ). This ion is isoelectronic with N2, and its Lewis structure, [ C=C ], has a carbon-carbon triple bond. The most important ionic carbide is calcium carbide (CaC2), produced by the reduction of CaO with carbon at high temperature ... 

Pinkert, K., M. Oschatz, L. Borchardt et al. 2014. Role of surface functional groups in ordered mesoporous carbide-derived carbon/ionic liquid electrolyte double-layer capacitor interfaces. ACS Applied Materials Interfaces 6 2922-2928. 

Interstitial carbides, which are INTERSTITIAL COMPOUNDS of carbon with transition metals. Titanium carbide (TiC) is an example. These compounds are all hard solids with high melting points and metallic properties. Some carbides (e.g. nickel carbide M3C) have properties intermediate between those of interstitial and ionic carbides. 

The ionic carbides, containing either the Cf or C" anions, are often prepared by the reaction of either the elements themselves or a metal oxide with carbon in an electric furnace at elevated temperatures. They can be hydrolyzed to produce various hydrocarbons in industrial processes. For example, calcium carbide, CaC2, is a major source of acetylene (briefly discussed on p. 372) as shown in Equation (15.14), and aluminum carbide, as shown in Equation (15.15), generates methane ... 

Ionic Carbides Compounds composed of carbon and a low-electronegativity metal such as an alkali metal or an alkaline earth metal are ionic carbides. Most ionic carbides contain the dicarbide ion, C2, cotmnonly called the acetylide ion. For example, calcium carbide has the formula CaC2 and a structure similar to that of NaCl (Figure 22.18 ). Calcium carbide forms by the reaction of calcium oxide with coke in an electric furnace. 

Descaibe the difference between an ionic carbide and a covalent carbide. Which types of atoms will form these carbides with carbon ... 

Ionic carbides are composed of carbon, generally in the form of the carbide ion, 2 , and low-electronegativity metals, such as the alkali and alkaline earth metals. Covalent carbides are composed of carbon and low-electronegativity nonmetals or metalloids, such as silicon. 

Calcium Carbide and its Derivatives. Although hydrocarbon-based acetylene production has become mote important, eady manufacture of acetylene was based on manufacture of the iatermediate, calcium carbide [73-20-7J, CaC2. This ionic acetyUde is produced by reaction of lime and carbon ia electric-arc furnaces (16). 

Using the periodic table as a guide, predict which of the following compounds form ionic solutions in water silicon carbide, SiC magnesium bromide, MgBr2 carbon tetrabromide, CBr chromic chloride, CrCl3. 

Compounds containing carbon in a negative oxidation state are properly called carbides, and many such compounds are known. In a manner analogous to the behavior of hydrogen and boron, carbon forms three types of binary compounds, which are usually called ionic, covalent, and interstitial... 

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