Surname Centre No. Initial(s) Paper Reference 4 3 3 5 Candidate No. 2 H Signature Paper Reference(s) 4335/2H Examiner’s use only London Examinations IGCSE Team Leader’s use only Chemistry Paper 2H Higher Tier Wednesday 17 June 2009 – Morning Time: 2 hours Materials required for examination Nil Items included with question papers Nil Question Leave Number Blank 1 2 3 4 5 6 7 8 9 Instructions to Candidates In the boxes above‚ write your centre number‚ candidate number‚ your surname
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substances. Crude oil is also a naturally occurring hydrocarbon. Hydrocarbons are molecules that contain hydrogen and carbon and come in various lengths and structures‚ like rings and straight and branched chains. Petroleum contains many alkanes and alkenes and has several impurities when removed from underneath the earth. Refining petroleum entails both the removal of these impurities and also the separation of petroleum into its various components. The specific method for this separation in crude oil
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Overall reaction: (McFadden‚ 2012) In the first step‚ the mixture of water‚ concentrated sulphuric acid‚ and cyclohexene was shaken vigorously until it became a homogenous solution. Followed by‚ the addition of water‚ and the distillation process lead to the hydrolysis of the alkene. Finally‚ addition of diethyl ether to the mixture then distillation took place to be purified and to obtain the final product‚ cyclohexanol (McFadden‚ 2012). Diethyl ether was used to extract alcohol from salt-water mixture
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Comment: Treat a Grignard reagent as an alkyl nucleophile i.e. CH3MgBr is equivalent to CH3- 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
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first-hand investigation to compare the reactivity of an alkene with its corresponding alkane. (a) State the name of the alkene. 2002:16(a) 1 (b) Outline a procedure to compare the reactivity of this alkene with its corresponding alkane. 2002:16(b) 2 (c) Describe the results obtained from this first-hand investigation and include relevant chemical equations. 2002:16(c) 3 3 Explain why alkanes and their corresponding alkenes have similar physical properties‚ but very different
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Diels-Alder reactions are steriospecific (cis-alkenes form cis substituted and trans-alkenes form trans-substituted); this is called syn addition‚ the configuration of dienophiles is always retained in the product. The diene and dienophile react in such a way that the endo product is formed rather than the exo
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the base to lose a hydrogen and form the carbon-carbon double bond [1]. When the more substituted alkene is the dominant product‚ the reaction follows Zaitsev’s rule. Zaitsev’s rule states that the major product of a β-elimination reaction is the most stable alkene [1].Acid-Catalyzed Dehydration is the elimination of a molecule of water from adjacent carbon atoms. An alcohol can be converted to an alkene by dehydration‚ which is often brought on by heating the alcohol with either 85% phosphoric acid
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excess water. The water will remove the acidic hydrogen on the carbocation producing the desired alkene as well as regenerating the acid catalyst (fig. 2). A time effective way to collect the 4-methylcyclohexene is to heat the reaction to reflux as it is taking place. This allows the product to be separated from the starting materials by means of the boiling point discrepancy between the isolated alkene (101-102C) and the starting alcohol (171-173C). After the distillate is collected any impurities
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2950 cm-1 sp2 C-H stretch 3100 cm-1 C=O - ketone 1715 cm-1 C=C alkene 1680 cm-1 O O d. e. f. OH sp3 C-H stretch 2950 sp C-H stretch 3310 cm-1 CC alkyne stretch 2220 cm-1 cm-1 sp2 C-H stretch 3100 cm-1 sp3 C-H stretch 2950 cm-1 C=C alkene 1680 cm-1
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which contained in its IR spectrum the functional groups O-H (at 3520 cm-1)‚ sp2 C-H (3080 – 3000 cm-1)‚ aliphatic C-H (2980 – 2940 cm-1)‚ and both alkene C=C (at 1640 cm-1) and aromatic C=C (at 1514 cm-1). The IR spectrum is attached to this report. These data are consistent with the structure of eugenol‚ shown in Figure 2 below: In addition‚ the IR of the product from the steam distillation of cloves closely corresponds with that of an authentic sample of eugenol shown in the lab text.9
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