What is Substitution: Definition and 815 Discussions

A substitution reaction (also known as single displacement reaction or single substitution reaction) is a chemical reaction during which one functional group in a chemical compound is replaced by another functional group. Substitution reactions are of prime importance in organic chemistry. Substitution reactions in organic chemistry are classified either as electrophilic or nucleophilic depending upon the reagent involved, whether a reactive intermediate involved in the reaction is a carbocation, a carbanion or a free radical, and whether the substrate is aliphatic or aromatic. Detailed understanding of a reaction type helps to predict the product outcome in a reaction. It also is helpful for optimizing a reaction with regard to variables such as temperature and choice of solvent.
A good example of a substitution reaction is halogenation. When chlorine gas (Cl2) is irradiated, some of the molecules are split into two chlorine radicals (Cl•) whose free electrons are strongly nucleophilic. One of them breaks a C–H covalent bond in CH4 and grabs the hydrogen atom to form the electrically neutral HCl. The other radical reforms a covalent bond with the CH3• to form CH3Cl (methyl chloride).

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  1. C

    Trigonometric substitution integrals

    what would be the appropriate trigonometic substition for the following: 1.) \int(7x^2-7)^{3/2}) dx 2.) \int \frac{x^2}{\sqrt{(7x^2 + 8)}} ok i have a book with a list of trigonometric functions in front of me, but i don't get it. i don't see anything that i can sub in for. ok i...
  2. K

    Calc II substitution integration

    Hi all, I'm totaly lost on how to get started on this one. Integrate 1dx/(x^(1/2)(1-x)^(1/2)) The solution manual jumps right through the substitution and ends up as Integrate (2u*du)/(u(1-u^2)^(1/2)) I'm just not seeing it, little help please. Keith
  3. C

    Math Substitution for Solving Equations | Attached Picture Included

    the problem is shown in the picture i attached. wouldnt i use u = 2sec(\theta) as a sub?
  4. A

    Simple Integration by Substitution

    Please help. I'm having trouble with a simple integration by substitution problem The integrand is f(x) = x* sqr(x-1) The interval [1,2] Please draw it out in a gif file and send it to me via email. -much appreciated.
  5. marlon

    Calculate the substitution resistance

    hi guys, i need to calculate the substitution resistance between the points A and B of the chain in the attached picture. Each rectangle is a resistance R , except the resistance on the right-top of the figure. That has value 2R ; and the solution has to be (13/11)R. I know that we have to...
  6. G

    Integration via substitution problem.

    Hi, I'm currently stuck on an integration via substitution problem. I have an answer but the one given in the book of the book is different to mine. I'm wondering where exactly I've gone wrong, if i have: Q10: Integrate: x/ (x+1)^0.5 dx. Use the substitution, u^2 = x + 1. Heres my...
  7. K

    U substitution for differentiation?

    How do I evaluate: d/dt sqrt [ t^4 + t^2 ]= 0 to get a max/min value. can I make a u substitution of some sort?
  8. A

    Liskov substitution principle?

    Hello, everyone... I am new to OOP, and this is the first time I make a question on PF, hope you can help me out. I am not sure about this principle. Can you tell me in what ways I can *break* Liskov substitution principle ? Thanks, ~Alek
  9. C

    Velocity Calculation with c^2 Substitution

    If this equation is true: V=(V1+V2)/(1+(V1*V2)/c^2) Then why is it when you plug in c^2 for both V1 and V2 you get the total velocity as 2m/s
  10. J

    Why is substituting for \int\frac{dx}{x^4+1} so difficult?

    \int\frac{dx}{x^4+1} What really frustrates me is that I've seen this integral before. I believe it involved some whacky subsitution like x=e^u, but no substitution seems to work. Partial fractions just make a mess. Trig subs seem tempting but that 4 screws everything up. Ideas?
  11. E

    Ligand substitution & first row transition metal complexes

    anybody know what the primary mode of ligand substitution for first row octahedral transition metal complexes?
  12. C

    Integration By Substitution and Line Integrals

    For our homework this week for Pure, one of the questions is to ingration 1/(16 + x^2) with respect to x between the limits 0 and 4. I know the result from the formula wqith arctan in it, but since we've to use substitituion here and not just plonk down the formula, I'm confused as to what to...
  13. C

    Integragtion Problem with Substitution

    At the moment I'm trying to solve this integration problem and it's not working out asd neatly as any other substituion problem I've tried before. We have to integrate sqrtx divided by (1 + x^2) using the substitution x= tan^2t (as in tan squared t). So when we have dx/dt so you get...
  14. K

    How to integrate without trigonometric substitution

    S(x²(1-x²)¹/²)dx without use x=sen(T)? Sx^2(1-x^2)^1/2dx x=sen(t) dx=cos(t)dt (-pi/2<=t<=pi/2) S(x^2(1-x^2)^1/2)dx=S(sen^2(t)cos^2(t))dt S(sen^2(t)cos^2(t)^)dt=S((1-cos^2(2t))/4)dt =S1/4dt - S((co^2(2t))/4)dt= t + c1 - S((1-cos(4t))/8)dt =t/4 + c1 - S1/8dt + S(cos(4t)/8)dt= t/4 +...
  15. E

    Integration by substitution question

    How do you do this question, I've spent hours figuring it out: Use the substitution x = 3sint to show that 3 [inte]x^2[squ](9-x^2) dx = (81/16)pi 0
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