Hydrogen short

Note that only the hydrogens on the a positions of carbonyl compounds arc acidic. Hydrogens at 7. d, and sc on, arc not acidic and can t be removed by base. Well account for this unique behavior of o hydrogens shortly. 

The formula CioHigO is four hydrogens short of a saturated structure and therefore implies that there are either two rings or two double bonds... 

How is this concept useful Let us say that we have isolated a hydrocarbon of molecular formula QHg. If this had been an acyclic alkane, we would have expected 2 + 2 hydrogens, in this case 14. So we are six hydrogens short. So we must have three rings or double bonds, for example, 3.3, 3.4, or 3.5. We can generalize this to say that if we have carbon atoms and m hydrogen atoms, then (DBE) = 2n + 2) - m /2. Halogens count as if they were hydrogens. 

The conversion takes place at high temperature (820-850°C) and very short residence time (hundredth of seconds) in the presence of steam. The by-products are hydrogen, methane and a highly aromatic residual fuel-oil. 

The major role of TOF-SARS and SARIS is as surface structure analysis teclmiques which are capable of probing the positions of all elements with an accuracy of <0.1 A. They are sensitive to short-range order, i.e. individual interatomic spacings that are <10 A. They provide a direct measure of the interatomic distances in the first and subsurface layers and a measure of surface periodicity in real space. One of its most important applications is the direct determination of hydrogen adsorption sites by recoiling spectrometry [12, 4T ]. Most other surface structure teclmiques do not detect hydrogen, with the possible exception of He atom scattering and vibrational spectroscopy. 

Dissolve 2 ml. of acetaldehyde in 5 ml. of dry ether, cool in a freezing mixture of ice and salt, and pass in dry hydrogen chloride gas for 30-60 seconds. The solid polymer, metaldehyde, may separate in a short time, otherwise cork the tube and allow it to stand for 10-15 minutes. Filter ofiF the crystals. 

Place a mixture of 1 0 g. of the hydrocarbon, 10 ml. of dry methylene chloride or ethylene dichloride or syw.-tetrachloroethane, 2 5 g. of powdered anhydrous aluminium chloride and 1-2 g. of pure phthalic anhydride in a 50 ml. round-bottomed flask fitted with a short reflux condenser. Heat on a water bath for 30 minutes (or until no more hydrogen chloride fumes are evolved), and then cool in ice. Add 10 ml. of concentrated hydrochloric acid cautiously and shake the flask gently for 5 min utes. Filter oflf the solid at the pump and wash it with 10-15 ml. of cold water. Boil the resulting crude aroylbenzoic acid with 10 ml. of 2 -5N sodium carbonate solution and 0 2 g. of decolourising carbon for 5 minutes, and filter the hot solution. Cool, add about 10 g. of crushed ice and acidify... 

Earlier, we eonsidered in some detail how the three Ish orbitals on the hydrogen atoms transform. Repeating this analysis using the short-eut rule just deseribed, the traees (eharaeters) of the 3 x 3 representation matriees are eomputed by allowing E, 2C3, and... 

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