fractions from the refining of petroleum Catalytic cracking is the process whereby high molecular weight fractions are broken down to low molecular weight ones. This process is used in petroleum refineries where crude oil is broken down to smaller alkenes and alkanes‚ until ethene‚ propene‚ (or both) are formed. Catalytic Cracking allows greater output of high-demand products. Identify that ethylene‚ because of the high reactivity of its double bond‚ is readily transformed into many useful products Ethylene
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Ethers have much lower boiling points compared to alcohols of comparable MWs. BPs of ethers increases with increasing MW. BPs of isomeric ethers increase with increasing alkyl chain length. BPs of ethers are about the same as those of alkanes of comparable MWs. Solubility of ethers in water is comparable to that of alcohols. As chain length of ethers increases‚ solubility in water decreases. Branching of the alkyl chain results in greater solubility since London forces are weaker
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triphenylmethanol using through Gridnard reaction 2. To study the operations of anhydrous reaction‚ water vapor distillation. Principles Alcohol is widely used in organic chemistry‚ not only as solute but also as intermediate to synthesize halide‚ alkene‚ ether‚ aldehyde and ketone etc. In laboratory‚ an important method of synthesizing alcohol is though the addition reaction of Gridnard reagent and carbonyl compound‚ whereas aldehyde is the most reactive and then to ketone or ester. Primary alcohol
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C and H atoms. They include the alkanes‚ alkenes‚ alkynes‚ and aromatic hydrocarbons. Because of their relatively nonpolarity‚ all hydrocarbons are insoluble in water. Hydrocarbons may be divided into two large classes namely: Saturated hydrocarbons and unsaturated hydrocarbons. Saturated hydrocarbons are the simplest type of organic compounds. They are hydrocarbons in which all carbon-carbon bonds are single bonds. An example of a saturated hydrocarbon is an alkane. Unsaturated Hydrocarbons are hydrocarbons
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dispersion forces). The magnitude pof Van der Waals force depends on the relative molecular mass‚ high mass produces a larger force. Boiling points of the alkanes data and alkenes data These very clearly illustrate the effect of increasing Van der Waals attractions as the relative molecular mass increases. The influence of branching in the alkanes can also illustrate the effect of different surface areas on the Van der Waala forces (the more branching the lower the b.p) Dipole-dipole forces --
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1. A student neglected to add sodium carbonate when extracting the tea leaves with hot water. Yet a very high yield of caffeine was obtained. The crystals melted at 202-214°C. Explain. • The sodium carbonate is supposed to be added when extracting the tea leaves with hot water in order to help purify the caffeine. So since the student neglected to add sodium carbonate the caffeine won’t be pure but the student would still be able to recover a large amount of caffeine. The literature melting point
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ALCOHOLS Alcohols are compounds in which one or more hydrogen atoms in an alkane have been replaced by an -OH group. For the purposes of UK A level‚ we will only look at compounds containing one -OH group. For example: Primary alcohols In a primary (1°) alcohol‚ the carbon which carries the -OH group is only attached to one alkyl group Some examples of primary alcohols include: Secondary alcohols In a secondary (2°) alcohol‚ the carbon with the -OH group attached is joined directly to
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nucleophile. The Grignard reagent can also react with RX to form a longer chain alkane. Example: CH3CH2MgBr + CH3CH2Br CH3CH2CH2CH3 + MgBr2 In general‚ basicity parallels nucleophilic strength since both of them depend on the availability of the lone pair of electrons. The Grignard reagent is not only able to function as a nucleophile; it can operate as a base too by reacting with water to form an alkane. Example: CH3CH2MgBr + H2O CH3CH3 + Mg(OH)Br Based on the diagonal relationship
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(note: there is CO2 solid‚ its dry ice) – Complete combustion: ▪ hydrocarbon + oxygen [pic] water + carbon dioxide – Displacement reactions: ▪ Y + X (anion)[pic] X + Y (anion); where Y > X on activity series or Eo table. • Alkene/alkane reactions: – Cracking of pentane: ▪ pentane [pic] ethylene + propane ▪ C5H12 (g) [pic] C2H4 (g) + C3H8 (g) – Hydration of ethylene (the reverse can also happen known as de-hydration‚ where concentrated acid is used):
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Chemistry Essay Butane‚ Butene and all isomers that come with them are considered to be alkanes and alkenes respectively. They differ from each other in the fact that Butane contains only single bonds‚ whereas Butene has both single and one double bond. Regardless of this difference in many situations the two molecules can display similar behaviours. For the purposes of this comparison But-1-ene will be used as ‘Butene’ unless otherwise indicated. But-1-ene is almost identical to the other
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