Thursday, August 12, 2010
aldol condensation
aldol condensation
(i) With hydroxylamine : Aldehydes and ketones react with hydroxylamine to give corresponding oximes containing (> C = N - OH) group. The reaction is carried in the presence of a base like NaOH.(a) Acetaldehyde with hydroxylamine gives acetaldoxime. h hI ________ICH3 - C = Jo + _H2]nOH ) CH3 - cf NOH + HzO *acetaldehyde acetaldoximeCH3 CH3 ....CH3 - c =€f +~H21NOH ) CH3 - c = NOH + H20i____.Z'i ; - acetone acetoxime (ii) With hydrazine : Aldehydes and ketones react with hydrazine to give corresponding hydrazones. h h 1 r-___„ * IH3C-C = jO + H2|- N-NH2-> H3C-C =N-NH2 + H2O acetaldehyde acetaldehyde hydrazone ch3 ch3 I .1 h3c - c =jo_ + JH2_j- n - nh2—> h3c - c = n - nh2 + h2oacetone acetone hydrazone(iii) With phenylhydrazine : Aldehydes and ketones react with phenylhydrazine to give the corresponding phenylhydrazone.(a) Acetaldehyde with phenylhydrazine gives acetaldehyde phenylhydrazone.H HI Ich3 - c = jo + H2j nnhc6h5 -4 ch3 - c = nnhc6h5 + h2oacetaldehyde acetaldehyde phenylhydrazone(b) Acetone with phenylhydrazine gives acetone phenylhydrazone.CH3 CH3I ICH3- C=iO + H^N -NH-CgHs —» CH3-C = N-NH_C6H5 +H20acetone acetone phenylhydrazone(iv) Aldol condensation : Aldehydes or ketones containing active a-hydrogen atom, i.e. hydrogen on the carbon atom adjacent to carbonyl group (a-carbon atom) give P-hydroxy aldehyde, i.e. aldol or p-hydroxy ketone respectively on warming with dilute solution of sodium hydroxide (10%) or sodium carbonate. This reaction is known as aldol condensation. Formaldehyde and benzaldehyde do not give this reaction as they have no a-hydrogen atom. Aldol contains an aldehydic group (-cho) and also alcoholic group (-oh). (Aid for aldehyde group and -ol for alcohol, hence the name aid + ol = aldol.)(a) This is an addition reaction. This addition takes place in such a way that a-carbon atom of one aldehyde molecule is attached to the carbonyl carbon of the second molecule and a-hydrogen of one aldehyde is attached to carbonyl oxygen of the other to give P-hydroxy aldehvde.Aldol loses one water molecule on heating with an acid to form unsaturated aldehyde.When aldol condensation takes place between two molecules of different aldehydes, then it is known as cross aldol condensation. h h I „ Na2C03 I „ch3ch2c =o+hch2c = o-> ch3ch2-cp-ch2-c = o| solution ( |h oh hpropionaldehyde acetaldehyde propionaldol(b) Certain ketones like acetone in presence of barium hydroxide or sodium hydroxide give diacetone alcohol (p-hydroxy ketone). CH3 H O CH3 H O I I II Ba(OH)2 J J II CH3 -C + H-c«-c-CH3---^ cha-pc-aC -C-CH3Oh oh hacetone acetone diacetone alcohol(4-hydroxy, 4 -methyl, pentan-2-one)modern periodic table
modern periodic table
Learn table of Pythagorean related trigonometric identities:cos2θ + sin2θ = 1sin θ = ± `sqrt(1 - cos^2 theta)`cos θ = ± `sqrt(1 - sin^2 theta)`sin θ = `1/(csc theta)`cos θ = `1/(sec theta)` tan θ = `1/(cot theta)`csc θ = `1/(sin theta)` sec θ = `1/(cos theta)` cot θ = `1/(tan theta)`1 + tan2θ = sec2θ1 + cot2θ = csc2θsin θ = ± `(tan theta)/(sqrt(1 + tan^2theta))`cos θ = ± `1/(sqrt(1 + tan^2theta))`tan θ = ± `sqrt(sec^2 theta - 1)`csc θ = ± `(sqrt(1 + tan^2theta))/(tan theta)` sec θ = ± `(sqrt(1 + tan^2theta))`cot θ = ± `1/(sqrt(sec^2 theta - 1))`Learn table of symmetry related trigonometric identities:sin (-θ) = - sin θ cos (-θ) = + cos θ tan (-θ) = - tan θ csc (-θ) = - csc θ sec (-θ) = + sec θ cot (-θ) = - cot θ sin (∠- θ) = + sin θcos (∠- θ) = - cos θtan (∠- θ) = - tan θcsc (∠- θ) = + csc θsec (∠- θ) = - sec θcot (∠- θ) = - cot sin (`pi/2` - θ) = + cos θcos (`pi/2` - θ) = + sin θtan (`pi/2` - θ) = + cot θcsc (`pi/2` - θ) = + sec θsec (`pi/2` - θ) = + csc θcot (`pi/2` - θ) = + tan θLearn table of shifts and periodicity related trigonometric identities:sin (θ + `pi/2` ) = + cos θ cos (θ + `pi/2` ) = - sin θ tan (θ + `pi/2` ) = - cot θ csc (θ + `pi/2` ) = + sec θsec (θ + `pi/2` ) = - csc θ cot (θ + `pi/2` ) = - tan θ sin (θ + âˆ) = - sin θcos (θ + âˆ) = - cos θtan (θ + âˆ) = + tan θcsc (θ + âˆ) = - csc θsec (θ + âˆ) = - sec θcot (θ + âˆ) = + cot θsin (θ + 2âˆ) = + cos θcos (θ + 2âˆ) = + sin θtan (θ + 2âˆ) = + cot θcsc (θ + 2âˆ) = + sec θsec (θ + 2âˆ) = + csc θcot (θ + 2âˆ) = + tan θprocess mapping examples
process mapping examples
1)What is the addition of the following array in math. Solution The given array is as follows, Now we can add the numbers . This is the addition process.2)What is the difference of the following Array? Solution The given array is as follows, Now subtract the second group from the first group. This is the process of the subtraction.3) Multiply the following array. Solution Here we can multiply the first row of the first group into all columns of the second group. So the multiplication is as follows, This is the multiplication process.math test generator
math test generator
Example 1- Study online exponential generating functionDraw the graph for given exponential function `f(x)=(50/25)+e^x`Solution: We have to find the corresponding value of f(x) by substituting the value of x. After find out the f(x)-value for all x-value make them into table format as represented below.`f(x)=(50/25)+e^x``f(0)= (50/25)+e^0=3``f(1)= (50/25)+e^1=3.718``f(2)= (50/25)+e^2=9.38``f(3)= (50/25)+e^3=22.08`x0123f(x)34.7189.38922.08 When plotting the graph we have to assume scale as per our x and f(x) value. After find out the x-value and y-value ie f(x) we have to mark the points on a graph sheet then we have to join the points as coordinate respectively.Scale:In x-axis 1 unit=1 cmIn y-axis 1 unit=5 cmGraph for the given function is given belowequation for photosynthesis
equation for photosynthesis
Before 1930, it was considered by physiologists that one molecule each of CO2 and H2O form a molecule of formaldehyde (HCHO), of which 6 mols are polymerized to one molecule of glucose (a hexose sugar).LightCO2 + H2O -> HCHO + 02Chlorophyll (Formaldehyde) Polymerization6CH20 (or 6HCHO)-> C6Hi206(Formaldehyde) (Hexose sugar)However formaldehyde is a toxic substance which may kill the plants. Hence, formaldehyde hypothesis could not be accepted.On the basis of discovery of Nicolas de Saussure (1804) that "The amount of O2 released fromplants is equal to the amount of CO2 absorbed by plants", it was considered that O2 released inphotosynthesis comes from CO2, but later on it was proved wrong.In 1930, C.B. van Niel proved that, sulphur bacteria use H2S (in place of water) and CO2 tosynthesize carbohydrates as follows :6CO2 + 12H2S-> C6H1206 + 6H20 + 12SThis led van Niei to the postulation that in green plants, water (H2O) is utilized in place of H2Sand O2 is evolved in place of sulphur (S).6C02 + 12H20-> C6H1206 + 6H20 + 602This was confirmed by Ruben and Kamen in 1941 using chlorella a green alga. He used water(H20), having heavy isotope of oxygen (O18), oxygen of 18 atomic weight (normal oxygen is of 1618atomic weight) and found that oxygen released in the process of photosynthesis was of O 0 type (i.e., heavy oxygen). On the contrary when CO28 was used, the released oxygen was of normal type, i.e., O26. From this it can be concluded that, oxygen released by green plants comes from splitting of water (oxidation of water).Furthermore because 6 molecules of oxygen can be produced by 12 molecules of water only, the summary equation of photosynthesis is written as follows :Oxygenic and Anoxygenic Photosynthesis(i) Oxygenic photosynthesis (with evolution of O2) is found in eukaryotes and cyanobacteria. Water acts as H-donar to produce NADP.2H thus photolysis of water is essentialLightC02 + H2O-> Sugar + OxygenChlorophyll(ii) Anoxygenic photosynthesis (without the evolution of O2) is found in photosynthetic bacteria. H2S acts as H-donar and no photolysis of water is needed.LightCO2 + H2S-> Sugar + Sulphur or other oxidised compounds orChlorophyll some other inorganic compoundsAnoxygenic photosynthesizing forms are strictly anaerobic and thus O2 acts as a poison for them.alternating current generator
alternating current generator
An AC circuit consists of combinations of circuit elements like resistors, inductors and capacitors fed by an AC generator which provides sinusoidal voltage. To analyse an AC circuit is to find the current through the given circuit and the phase difference between the current and the applied voltage.
Subscribe to:
Comments (Atom)