ORGANIC CHEMISTRY A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site alkanes The simplest of organic compounds. Alkanes are saturated hydrocarbons with the general formula CnH2n+2. The first few in the series are methane, ethane, propane, butane, and pentane. Lower members in the series are gases; higher members are waxy solids. Alkanes are present in natural gas and petroleum. They higher members can be cracked to form smaller alkanes and alkenes. Alkanes are converted into other compounds by replacing a hydrogen with other functional groups. The most important substitutions for biochemistry are -OH (alcohol), -CHO (aldehyde), -COO-R- (ester, R=alkyl group), -COOH (carboxylic acid), -PO4 (organic phosphate), and -NH2 (amine). Cracking Cracking is a form of thermal decomposition, which breaks long chain hydrocarbons, many of which are not very useful, into shorter molecules by heating them. Many of the substances with longer molecules produced from the fractional distillation of crude oil are cracked; for example, naphtha is cracked to produce gasoline. Cracking also produces extra alkenes, which are needed for making plastics. In industrial cracking, vaporized hydrocarbons are passed over powdered aluminum oxide catalyst at a temperature of 400°–700°C. Since any of the C–C bonds in a molecule can break, the result is a mixture of products, although the conditions for the reaction are chosen to favor some products over others. Related category    • ORGANIC CHEMISTRY Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP