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Complete the following reactions : a. b. c. d. e. f. g. h. i. Alkenes like ethene dissolve in conec. H_(2)SO_(4) but alkynes like ethyne do not dissolve in cone. H_(2)SO_(4), whereas but -2 yne dissolves. Explain. j. Identify X,Y and Z k. l. 2CH_(2)=CH_(2)+underset("mono-chloride")underset("Sulphur")(S_(2)Cl_(2))rarr(R )+underset("Sulphur")(S) m. n. |
Answer» Solution :a.  b.  Due to the -I effect of theree `F` atoms, addiction is anti - Markovnikov's `9` negative part of the addendum is adding to the `C` atom containing more number of `H` atoms ). The resonance effect (+R effect) from the lone pair `vec (e)` 's of `F` atomes is not operative because lone pair `vec(e)'s` and double bond are not in conjugation. So the `-I` effect of`F` atoms is operative and, hence, the electronic effect of double bond takes place from `C_(1)` to `C_(2)`. c.  Here, `+R` effect is more operative than `-I` effect of `O ` atom, since the lone pair on oxygen and double bond are inconjugation. Moreover, `R gt 1,` so Markovnikov's addition takes place. d.  (Same explanation as in part (c)above) e.  Vinyl carbonium ion Since, alkyl carbonium ion is more stable than vinyl carbonium ion, alken reacts at a faster rate than alkynes towards `EA`. f.  g.  `2-` Chloro`-`prop`-1-`ene(Markovnikov's add.)2,2-Dichloropropane[Same explanation as in part (c)above.] h.  `2-`Methyl`-` but `-2-`ene`(Markovnikov's add.)Alternatively, `+I` effect of two `Me` groups on `C-2` is greater than `+I` effect of ONE `Me` group on `C-3`. So, the electronic effect operates from `C-2` to `C-3`, forming `C-2` (positive) and `C-3(` negative), hence, the addition takes place ACCORDINGLY.  Since, with `HCI` and `HI` the peroxides effect does not take place, addition takes place according to Markovnikov's role. `i. `  Since, alkyl carbocation salt is more stable than vinyl carbocation salt, ethene dissolves, whereas ethyne does not dissolve in conc. `H_(2)SO_(4)`.  Vinyl carbocation salt`2-` hydrogen sulphate `-` but`-2-`ene In this case, vinyl carbocation salt in more stabilised than vinyl carbocation sal with `(CH-=CH)`, due to `+I` effect of `(CH_(3)-)` group, hence, soluble in conc. `H_(2)SO_(4)`. `j.` Write the structure of `2,3-` DIMETHYL butane and prceed in reverse manner to find the structure of `X`.  Here, `X` is an alkyl halide. It can be `III` or `IV`, BUT `III` can give two products, while `IV` can give only one product. So alkyl halide `X` is `III`.  Reactions are `:`  `k.`  `l. `  Mustard gas is a poisonous gas that was used in World War`I(1914-1918)`. It is also used as an anaesthetic. It is used in place of acctylene (ethyne) for welding purposes, in fruitindustry for the preservation and artificial ripening of green fruits such as organtes, BANANAS, and apples, andinthe manufacture of plastic and various solvents, such as glycol and dioxian. `m.` Lower alkene, when mixed with air and passed under pressure over a silver catalyst at 470-670K, adds an oxygen atom to give alkene oxide or epoxide.  Propylene oxide or `2-` Methyloxirane `n.` Epoxides are also obtained when alkenes are treated with per `-` acids (perbenzoic acid, `C_(6)H_(5)COOOH`) or their alkali metal SALTS. |
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