So, hello guys. Good morning. Today in this session, we are going to understand a very important concept of organic chemistry and that is substitution reaction. Okay, so there are two types of reaction mainly we have. It's not like only two types, but two types of reactions only we have, which affects the, you know, which those type of reactions takes place in chemical, in organic chemistry. Okay, just a second. So, today in this session, we are going to see substitution reaction, right? It's a long chapter. Okay, it's a long topic also. There are so many things, you know, we need to understand, to understand these kinds of reactions. But since this is, you know, oriented to oriented towards KVBY, so we'll only discuss the important topics here. Okay, so we are going to see substitution, substitution reaction. Okay, so if you look at the name, if you look at the name, it with the name only you can understand that there is substitution taking place, right? But substitution of what? That's the question. Substitution is taking place here. So first of all, what is a substitution reaction? Okay, so basically, when you look at the reaction, any example if I show you, okay, so suppose if I take this example, we have a compound, a molecule CH3Cl, CH3Cl, and this reacts with a compound of iron called SH-, SH- you can consider similar to, similar to OH-. Okay, SH-, OH-. All these are similar, so you can consider that. Okay, so if you see this to reaction, so in this what happens, this SH- is able to replace Cl- from the reaction, okay, and forms thiol as the, okay, and forms thiol as the product. So the product here depends upon what nucleophile we are using here. Okay, so this reaction takes place and this converts into CH3SH and Cl- goes out. Cl- goes out. So if you look at this reaction, this SH-, it displaces the chlorine over here. Okay, and suppose I am taking some solvent here, H2O. This reaction takes place in this solvent. Basically, the purpose of solvent is what is the reaction of, the medium of reaction. This molecule and this iron present in the solution and the reaction takes place. Medium it is basically. So what happens here? This iron substitutes chlorine in this molecule, hence it is a substitution reaction. Hence it is a substitution reaction. Okay, so what all things are there? You see this compound where the reaction takes place? This compound we call it as substrate. The compound on which the reaction takes place this SH-, this attacks on to this substrate, this particle. So this is attacking particle, attacking particle and this negatively charged attacking particle is nucleophile. This is obviously the product we have and this that goes out here, this is the, this is the leaving group we have, leaving group because it leaves from this molecule, it goes out leaving group. What is this H2O? This H2O is the solvent. So basically there are four different types of term that we are using here. We are using substrate, we are using attacking particles, we are using solvent, we are using leaving group. All these terms affects the substitution reaction. Okay, like I said there are different, different types of substitution reaction we have, 7A types of substitution reaction we have. Okay, and all these reactions depends upon these four factors, substrates, attacking particle that is nucleophile, solvent and leaving group. Correct? So this is what we need to understand, to understand the substitution reaction. Okay, so overall if I write down this reaction, the reaction is in general expression if I write down the reaction is we have RL the substrate and we have a nucleophile represented by this. I have taken here negatively charged but it's not like nucleophiles always negatively charged. It can be neutral also with lone pair of electrons. So either negative charge or neutral, possible. Okay, this is one type of attacking particle. We have another type also possible in presence of solvent. Yes you, RNU, the nucleophile displaces the leaving group and leaving group. Overall the reaction is this, right? Substitution reaction. This is what it is happening. Okay, this attacks over here and this goes out like this. Okay, so the substitution reaction like I said there are many different types of substitution reaction we have. But for KVPY, we are going to focus on only two that is SN1 and SN2, SN1 and SN2. Only these two we are going to focus on. Okay, SN1 and SN2. But before going into this, let us discuss these four factors here, substrates, attacking particle, solvent and leaving group. Okay, in short we will discuss the brief discussion we will have. So first of all, we write down substrate. So what are substrates? Substrates are generally the molecule which takes part in the reaction like supposedly I will write down here CH3Br. Right, we can also take a tertiary alkyne halide. Secondary also we can take BR. Okay, we can take benzyl group. Suppose this with CH2X, there are many other examples of substrates. Basically the molecule which taking the part in the reaction. So it depends on many. Basically you should focus on this is 1 degree alkyne halide, 3 degree, this is 2 degree and this is benzyl. Benzyl halide. Now the second one is the leaving group is the leaving group. Leaving group is the one which leaves into the reaction. Like I have given you the example CL- and L- that is the leaving group. Okay, now if I, if you see this reaction, okay the general reaction that I have written already, the reaction is RL plus Nu nucleophile react in presence of solvent RNU plus L minus. Now if this negative charge on this leaving group is stable, okay, then it is a good leaving. If negative charge is stable, then it is good leaving group. Good leaving group. LG represents leaving group. Okay, so more tendency to go out, more will be the rate of reaction. Okay, and tendency will be more to go out when this negative charge is stable. How do we find out the stability of negative charge? For that we have various effects, electronic effects, right, inductive effect, mesomeric effect and resonance. With all those points we can understand the tendency of this leaving group. Okay, but few orders you should all, you should know that the order of leaving group is this. Like if you talk about halogens, okay, chlorine is the poor living group among halogens. Chlorine, chlorine, then bromine, iodine. Iodine is the best leaving group we have. Chlorine is also a good leaving group. Iodine, I minus is most stable here because the negative charge is spread over a large volume. That's why the order is this. Okay, now if I show you some example here, suppose we have CS3, C double bond O, O minus. Okay, CS3, S double bond O, double bond O, O minus. Okay, so this negative charge is more stable because of more resonance. You have resonance this side, you have resonance here also with this double bond, with this double bond and here we have resonance with this double bond. So because of this extra double bond O, the negative charge is more stable and hence the leaving group ability is this. The second one is a better leaving group. Okay, next one if you talk about OH minus and SH minus, again the science factor is dominating here. Right, so SH minus is more stable, a better leaving group. If we talk about CH3O minus and phenoxide ion O minus, here we have resonance, this negative resonance stabilized, a better leaving group. Okay, so like this we can compare the leaving group ability also of any group. Any neutral molecules are better leaving group than the charged one. This one also you must remember. Neutral molecules, molecules are better leaving group, leaving group than than the charged one. Okay, for example, if you are comparing OH minus and H2O, H2O is a better leaving group than OH minus. Okay, RO minus and then the conjugate base of it ROH is a better leaving group than this. Okay, pH O minus and pH OH is a better leaving group. Okay, RC double bond O minus RCOOH is a better leaving group. This you must remember for leaving group. Okay, next you see solvent, the third factor we have that is solvent. Solvent, we have two types of solvent. Why it is required? It is required for for the movement of particles, required for the movement of particles. Right, and when the particle moves, they collide and reaction takes, that's why it is important. Okay, now this solvent we have two different types of solvent. Okay, solvent we have two types, solvent we have two types. The first one is polar solvent and the second one is non-polar solvent, polar and non-polar solvent. Polar solvent again classified into two categories that is polar protic and polar uprotic. Non-polar solvent, example of non-polar solvent is we have CCL4, SO2, benzene, all these are non-polar solvent. Non-polar solvent, the dipole moment is zero for non-polar solvent. That is the property of this. You must have studied this in physics, dipole moment because of the vector quantity. Okay, polar solvent, the dipole moment mu is not equals to zero. Little bit I'll talk about this dipole moment just a second. Now what is polar uprotic? Polar uprotic solvents are solvents in which solvents in which hydrogen atom is attached with hydrogen atom is attached with electronegative element like oxygen, nitrogen, chlorine, etc. These are polar uprotic solvents. Example of this solvent is, example of this solvent is we have H2O. So basically all these discussions are not required. You just need to know what is polar uprotic solvent and what is polar uprotic. You just need to know the few examples of it. So polar protic solvents like H2O, we can have alcohol, oxygen-hydrogen bond, we can have phenol, oxygen-hydrogen bond, we can have acid, oxygen-hydrogen bond, we can have amine, nitrogen-hydrogen bond. Okay, many examples we have in this. Now the another thing that you need to memorize here, okay I'll discuss this later. Polar uprotic solvent is what? Polar uprotic solvent or the solvent in which there is no hydrogen and electronegative element for example CH3 H3O, CH3. This we call it as dimethyl sulfoxide, DMSO. You'll get this only written in the example. Dimethyl sulfoxide, ethers. Ethers are also polar uprotic solvents. Okay and there are many examples. Okay, these two are important. I'm just trying to make you understand the things for KVPY. Okay, I'm not going to do any stuff. Okay, this is the effect of solvents. Okay, now one thing you know that the nucleophilic substitution, the substitution reaction that we have and since we're taking nucleophile here, like I'll give you the example RL plus Nu gives RNU. So it is the nucleophile which substitutes here, which gets substituted here. This reaction is nucleophilic substitution reaction. The reaction is nucleophilic substitution reaction. You look at this example this one. I have written SN1 and SN2. So what is this SN1 represents here? Substitution reaction in the general term. It is more specific. This particle is nucleophile. This is nucleophile. This nucleophile substitutes here and eliminates the living group Cl. Hence, the reaction is nucleophilic substitution reaction. Right, so this stands for SN1 stands for first order, first order nucleophilic substitution reaction, nucleophilic substitution substitution reaction. Okay, what is this order? You don't focus on this now. Just let it be. It is an experimental quantity. You should know what this SN1 stands for. This stands for first order nucleophilic substitution reaction. Similarly, this one stands for second order nucleophilic substitution reaction. Like I told you already that solvent also has effect on these kinds of reactions. So when you take polar protic solvent, okay, this one polar protic, this one favors SN1 reaction. Polar protic solvent favors SN1 reaction. Okay, polar aprotic solvent, this one, it favors SN2 reaction. It favors SN2 reaction. And since this is the nature we have for these two solvents, that's why you should know some examples of polar protic and polar aprotic. Again, I am telling you this SN1 and SN2 reactions are very competitive reactions. In all the reactions, we cannot say that only SN1 is taking place. Right, so there will be some amount of SN2 also, but we'll talk about the one which is dominating, which gives the major product. Okay, so any reaction in which the SN, the substitution nucleophilic substitution reaction is taking place, there we have the tendency for both type of reaction, SN1 and SN2 both. Okay, SN1 and SN2 both. The one which gives the major product, according to that only we say that this reaction goes under this particular mechanism, SN1 or SN2. Okay, so this is the third factor we have that is solvent. Now the last one we have here, that is, that is nucleophile. Again guys, I'm telling you this is not that important for your exam. Okay, this part because there are so many things here that we should know, we have to study, but I'm just giving you a brief idea of it. If you get any questions on this in case, you could find out the possible answers there. Okay, so nucleophile like I said it is the attacking particle. What is a nucleophile? It is either neutral or negatively charged, negatively charged, attacking particle, attacking particle. Okay, if it is neutral, then it must have known where like for example we have water, neutral nucleophile, phenol, neutral nucleophile, alcohol also, neutral nucleophile. Look at this reaction here. Suppose if I write down this CS3O minus plus CH3Cl, it gives CS3O CS3 and Cl minus leaves out. So how does this reaction happen here so far? You see this is more electronegative. We have discussed this, eye effect. Chlorine is more electronegative. So this chlorine attracts the bond pair of electron towards its side and this becomes delta negative and this becomes delta positive. Now with this we're trying to understand a little bit about the reaction, how the reaction takes place. Now when this becomes delta positive, so negative charge on this oxygen, this attacks onto this carbon since it is delta positive. And when this attacks over here, the Cl minus takes this bond pair of electron and goes out as a leaving group and we get this. This is nucleophilic substitution reaction. Now when you talk about this reaction, that is CH3O minus plus H2O, so reversible reaction, it converts into CS3OH and OH minus goes out. So here this one is not a nucleophilic substitution reaction. This one is acid-base reaction because why it takes X plus from the solvent and forms this. So if you look at the property here, both ions are same but this one is behaving as a nucleophile and this one is behaving as a base here. So there is a difference in nucleophile and base. Nucleophiles are better electron donors. They can give electron to this. And base city is tendency to accept H plus. It has less tendency to give electron pair to this. This is the one thing. So these are the four factors we have here which affects the rate of these reactions. So let us understand what is SN1 and SN2 reaction. So first type of nucleophilic substitution reaction we have that is right down the heading SN1 reaction. So like I said, it is first order nucleophilic substitution reaction, first order nucleophilic substitution reaction. Okay, the general term is what if you look at the reaction, it is very important to understand this because both SN1 and SN2 looks like similar if you do not understand the mechanism of it. Like suppose if I take here RL and some nucleophile in presence of solvent, it gives RNU plus L minus. Now you will definitely observe when we start discussing SN2 here then also I will write down the same reaction. This reaction only I will write down. Right, so if you do not understand the mechanism, mechanism means step by step description of a reaction. If you do not understand it, you won't understand then what is the difference between SN1 and SN2. So let us first understand the various steps involved in this reaction, that is the mechanism. Okay, so what happens the RN leaving group bond that we have, it is delta positive and delta negative. We have discussed this when we have alkyl halide, RCL, right, previous example we have seen. So this carbon and halogen bonds or nucleophile bond, it dissociates into finally dissociate, it converts into R plus and L minus. This takes this bond pair of electron and forms. Right, now this step is the slowest step we have, slowest step and it is RDS, rate determining step. Okay, RDS stands for rate determining steps. Okay, rate determining steps. So there are various steps involved in any reaction. The steps which is the slowest step is called the rate determining step. Means if you find out the rate of this reaction, we will consider this reaction, not the other one. Always we consider the slowest step. All this information I am giving you, correct. Now in the next step what happens, the second step of the reaction, the R plus and on this R plus, the nucleophile that you are taking, this nucleophile, this nucleophile attacks onto this R plus and forms a bond with the carbon atom which has the positive charge, R10. So this is how the product forms. Okay, it is a two step reaction and the product forms this overall the reaction is the solution. Now one very important point here that this R plus, it is the carbocation it is forming, carbocation forms. More stable carbocation, more will be the rate of the reaction. Okay, more stable carbocation, more will be the rate of the reaction. Now you will see when this carbocation forms, it means the leaving group must be very good. Then only it will go out and forms a carbocation. Right, must be very good. So property of which favours this reaction is what? That first of all write down characteristics of this reaction. So first of all, the carbocation forms here or I will write down the rate of the reaction, rate of the reaction, I will write ROR. The rate of the reaction is directly proportional to the stability of carbocation, stability of carbocation. Like I said SN1, SN2 both are competitive reactions. Okay, if there is tendency of forming stable carbocation, then it will be SN1 reaction. Why not SN2 will discuss that. Okay, but rate of the reaction is directly proportional to the stability of carbocation. Okay, rate also it is directly proportional to the nature, good leaving group. If the leaving group is very good, it can easily form carbocation and hence SN1 reaction favours. It is also inversely proportional to the basic strength of the leaving group. Basic strength means electron donating power. Okay, how it can take H plus from this. Okay, if this is a good base, this will easily attack onto this arpeggio sample. Even it won't wait, this nucleophile won't wait for this carbocation to form. Once the partial charge developed, this will attack onto this. This will attack onto this and the leaving group. But since it is SN1 reaction, so we have to have this step also, which is a formation of carbocation. So we should take the nucleophile, the strength of the nucleophile in such a way, the basic strength of this, that it wait for the carbocation to form. If it is very strong, the basic strength is very high for this nucleophile, then this won't wait for this fully developed carbocation to form, for this carbocation and this will attack on the partial charge only like this, we have discussed in the previous cases. So the basic strength of nucleophile should be weak so that it will wait for the carbocation to form and then it will attack on this. So this is the reason we have why the basic strength is weak. Now one very important thing here that is the, since the carbocation is forming, so the second property is the rearrangement of carbocation also possible, rearrangement of carbocation possible. And we do this rearrangement and this rearrangement happens, rearrangement happens in order to get more stable carbocation, more stable carbocation. This rearrangement is possible with hydride shift, hydride shift, methyl shift, methyl shift, phenyl shift, phenyl shift, etc. We will have these two, which is important. SN1 reaction, I have already told you, what is that shift I'll discuss, hydride shift management, I'll discuss that. I have already discussed polar-protic solvent is required for this, this I would suggest you must memorize this. Polar-protic solvent is required for this purpose. Okay, order of the reaction, I have already told you it is 1, SN1 it is order of the reaction is 1. So these are the few properties of this SN1 reaction. Okay, few properties of SN1 reaction. Now you look at this example and with this example we'll try to understand the hydride and methyl shift. Suppose we have a compound, consider this one, CS3C, CH3H, CH3CO. This when reacts with H2O. So here what happens you see this is the substrate and this is the nucleophile. Oxygen has no unfair, so it is nucleophile. Now what happens in this you see that this carbon has delta positive charge because it is delta negative, nucleophile. Right, so in the first step what happens the Cl- goes out and we'll get a convocation here which is this. CH3C, CH3H, CH3CO. Plus Cl- the leaving first step is this. In the second step what happens the H2O nucleophile which is this H2O. Oxygen has no unfair, it is a nucleophile. This has the tendency to attack on to this right but this actually won't happen here. If you consider this okay you can write down one product but that would be the minor problem. First of all I'll write down the product here. This attacks on to this and this converts into CS3C, CS3H, CH, CH3 and here we have H2O. Since oxygen loses its lone pyrrolechron so it has one positive charge. Positive charge on oxygen is not stable so to stabilize this one of the hydrogen here loses its electron to this oxygen and comes out as the H+. Okay it gives this electron here and H+. So the product of this reaction would be CH3CH, CH3, then CHOH, CS3. So you are getting an alcohol from alkali. Now this nucleophile could be anything. It can be anything for example that we have seen. We can have any nucleophile over here. So depending upon the nucleophile you'll get the final product. For this case we are getting an alcohol. Okay but this won't be the final product of this reaction. Okay because the carbocation is forming here. This carbocation goes under rearrangement. Okay see it is not like the rearrangement is always possible. Okay the purpose is to get the more stable carbocation. Okay so for that we'll do this rearrangement. If we don't do it actually in the reaction it happens on its own. It's not like we allow them to go under rearrangement. Wherever it is possible it goes under rearrangement forms the most stable carbocation of that molecule and then the nucleophile attacks. Right so first we'll get the most stable carbocation here and then the nucleophile attacks onto the same carbocation like it attacks over here and then it gives the final product. So here what happens the rearrangement takes place and rearrangement gives you the more stable carbocation which is nothing but this. You see one of the hydrogen from this takes this electron pair and it's rearranged itself onto this carbon. This is hydride shift one to hydride shift. So it goes under hydride shift hydride shift and forms this. What does it form? You see this here. It forms CH3, CCH3, CH2, CH3 and this carbon which loses this hydride ion gets a positive charge. Now you see you can compare the stability of this carbocation and this carbocation here. This carbocation the first one is getting stabilized through hyper conjugation here and the number of alpha hydrogen here would be 3 plus 1 that is 4. Here the number of alpha hydrogen would be 3 plus 3 plus 2 that is 8. So obviously more alpha hydrogen this one is more stable. Right so this is 1 comma 2 hydride shift gives you more stable carbocation. If further by any rearrangement we can increase the stability of carbocation we'll do that. It's not like only one time the rearrangement is possible. We can have n number of times but the only purpose is in every step you will be getting the more stable carbocation. In every step you'll be getting the more stable carbocation and then only it goes on. Otherwise more stable to less stable it won't go. Less stable to more stable it's possible. Okay now we get this carbocation here now you see one more thing here since hydrogen gets shipped over here it is hydride shift. Suppose we do not have hydride here but we have methyl group like this then 1 to methyl shift. If you have phenyl then phenyl shift. Right in this case not possible but depending upon the atom or group attached to it we call it as hydride shift, methyl shift, phenyl shift. Right what is the purpose of this shifting? The purpose the only one purpose is in every step we should get the more stable carbocation. Right that is the purpose. Now you look at this product in this reaction so finally we get this carbocation as the most stable carbocation in the given example this carbocation. Now this is similar now as the previous case we have water behaves as nucleophile. So this will attack onto this carbon atom and it converts into CCH3, CH2, CH3, O, H, H positive charge on it and hence finally H plus comes out from this carbon atom to stabilize the oxygen this bond pair comes over here and it converts into CCH3, CCH3, O, H, CH2, CH3. So this product is the major product of the reaction. Why major? Because it forms from the most stable carbon atom, major product. The previous one this product is the minor product of the reaction because it forms from the less stable carbocation, the less stable carbocation. Okay so what is the overall reaction here? The question was this if I write down the overall reaction we have discussed the mechanism of it but overall the reaction would be this CH3, CH3, CH2, CH3, CL with H2O. Correct? That the two product here we get is one is major other one is minor. The major product is you can directly you know do this if you do some practice you'll get it easily. First of all the carbon with halogen will get a positive charge here right and then one to hydride shift will get a positive charge here.  Okay the two possible product here we get is we have CH3, CCH3, O, H, CH2, CH3 plus the another product is CH3, CH3, CH3 and O. This one is major product and this one is minor. Okay so this is the overall reaction like this the reaction proceeds. Correct? So this is SN1 reaction. Always take care of one thing that in SN1 reaction will get carbocation first and then the nucleophile attacks on this and wherever the carbocation forms we always try to get the most stable carbocation. Okay one more property I forgot to write down here. The one more property you write down it is a two step reaction, two step reaction. Okay in the first step the no the carbocation forms and the second step the nucleophile attacks. Okay the rearrangement of carbocation all these things we consider in first step formation of carbocation is the first step. Okay guys I hope you have understood this okay there are like I said so many things that we should understand you must have some doubt also over here right but those things we could not do because of the time constraint I'm just trying to give you the basic idea of these reactions so that in that exam if it comes you can have an idea of that question and then you can give it a try at this. They are not going to ask you very tough questions. Few properties of leaving group and the polar protein solvent, polar protein solvent you should know the examples of these two based on that we can have the product in the reaction. Okay so thank you guys thank you so much next class we will start with Sn2 reaction okay we'll see Sn2 and then we'll see the various examples of both Sn1 and Sn2 and that is it for substitution. Okay thank you so much.


44 Crawling Stone Wash Where the little Crawling Stone River tears out of the Mission Mountain, it has left a grayish-white gap that may be seen for many miles. This is the head of the North Crawling Stone Valley. Twenty miles to the right, the Big River itself bursts through the Mission Hills in the canyon known as the Box. Between the confluence of Big and Little Crawling Stone and on the east side of Little Crawling Stone lies a vast waste. Standing in the midst of this frightful eruption from the heart of the mountains, one sees, as far as the eye can reach, a landscape utterly forbidding. North, for sixty miles, lie the high chains of the Mission Range, and a cup-like configuration of the mountains close to the valley affords a resting place for the deepest snows of winter and a precipitous escape for the torrents of June. Here, when the sun reaches its summer height, or a sweet grass wind blows soft, or a cloud bursts above the peaks strikes the southerly face of the Range, winter unfrocks in a single night. A glacier of snow melts within twenty-four hours into a torrent of lava and bursts with incredible fury from a thousand gorges. When this happens nothing withstands. Whatever lies in the path of the flood is swept from the face of the earth. The mountains are sailed in a moment with the ferocity of a hundred storms or ripped and torn like hills of clay. The frosted scale of the granite, the desperate root of the cedar, the poised nest of the eagle, the clutch of the crannied vine, the split and start of the mountainside are all as one before the June thaw. At its height little crawling stone with a head of forty feet is a choking flood of rock.  Even there they find no permanent resting place. Each succeeding ear sees them torn, groaning from their beds in the wash. New masses of rock are hurled upon them. New waters lift them in fresh caprice, and the crash and the grinding echo in the hills like a roar of mountain thunder. Where the wash covers the valley nothing lives. The fertile earth has long been buried under the mountain debris. It supports no plant life beyond the scantiest deposit of weed-plant seed, and the rocky scurff spreading like a leprosy over many miles scars the face of the green earth. This is the crawling stone wash. Exhausted by the fury of its few yearly weeks of activity, little crawling stone runs for the greater part of the year, a winding shallow stream through a bed of whiteen boulders where lizard sun themselves, and trout lurk in shaded pools. When Whispering Smith and his companions were fairly started on the last day of their ride, it was toward this rift in the mission range that the trail led them. Sinclair, with consummate cleverness, had rejoined his companions, but the attempt to get into the cash and his reckless ride into Medicine Bend had reduced their chances of escape to a single outlet, and that they must find up Crawling Stone Valley. The necessity of it was spelled in every move the pursued men had made for twenty-four hours. They were riding the pick of mountain horse-flesh and covering their tracks by every device known to the high country. Behind them, made prudent by unusual danger, rode the best men the mountain division could muster for the final effort to bring them to account. The fast riding of the early week had given way to the pace of caution. No trail sign was overlooked, no point of concealment directly approached, no hiding place left unsearched. The tension of a long day of this work was drawing to a close when the sun set and left the big wash in the shadow of the mountains. On the higher ground to the right, Kennedy and Scott were riding where they could command the gullies of the precipitous left bank of the river. High on the left bank itself, worming his way like a snake from point to point of concealment through the scanty brush of the mountainside, crawled wickwire, commanding the pockets in the right bank. Closer to the river on the right and following the trail itself over shale and rock in between scattered boulders, whispering Smith, low on his horse's neck, rode slowly. It was almost too dark to catch the slight discolorations where pebbles had been disturbed on a flat surface or the caulk of a horseshoe had slipped on the uneven face of a ledge, and he had halted under an uplift to wait for wickwire on the distance left to advance, when half a mile below him a horseman crossing the river slowly passed a gap in the rocks and disappeared below the next bend. He was followed in a moment by a second rider and a third. Whispering Smith knew he had not been seen. He had flushed the game and, wheeling his horse, rode straight up the river bank to high ground where he could circle around widely below them. They had slipped between his line and wickwires and were doubling back following the dry bed of the stream. It was impossible to recall Kennedy and Scott without giving an alarm, but by a quick detour he could at least hold the quarry back for twenty minutes with his rifle, and in that time Kennedy and Scott could come up. Less than half an hour of daylight remained. If the outlaws could slip down the wash and out into the Crawling Stone Valley, they had every chance of getting away in the night. And if the third man should be Barney Ripstock, Whispering Smith knew that Sinclair thought only of escape. Smith alone of their pursuers could now intercept them, but a second hope remained. On the left, wickwire was high enough to command every turn in the bed of the river. He might see them and could force them to cover with his rifle even at long range. Casting up the chances Whispering Smith riding faster over the uneven ground than anything but sheer recklessness would have prompted, hastened across the waist. His rifle lay in his hand, and he had pushed his horse to a run. A single fearful instinct crowded now upon the long strain of the week. A savage fascination burned like a fever in his veins, and he meant that they should not get away. Taking chances that would have shamed him in cooler moments, he forced his horse at the end of the long ride to within a hundred paces of the river, threw his lines, slipped like a lizard from the saddle, and, darting with incredible swiftness from rock to rock, gained the water's edge. From up the long shadows of the wash there came a wail of an owl. From it he knew that Wickwire had seen them and was warning him, but he had anticipated the warning and stood below where the hunted men must ride. He strained his eyes over the waist of rock above. For one half hour of daylight he would have sold in that moment ten years of his life. What could he do if they should be able to secrete themselves until dark between him and Wickwire? Gliding under cover of huge rocks up the dry water-course, he reached a spot where the floods had scooped a long hollow curve out of a soft ledge in the bank, leaving a stretch of smooth sand on the bed of the stream. At the upper point great boulders pushed out in the river. He could not inspect the curve from the spot he had gained without reckless exposure, but he must force the little daylight left to him. Climbing completely over the lower point he advanced cautiously and from behind a sheltering spur stepped out upon an overhanging table of rock and looked across the river-bottom. Three men had halted on the sand within the curve. Two lay on their rifles under the upper point, 120 paces from Whispering Smith. The third man, Seagrew, less than 50 yards away, had got off his horse and was laying down his rifle when the hood owl screeched again and he looked uneasily back. They had chosen for their halt a spot easily defended and needed only darkness to make them safe when Smith, stepping out into plain sight, threw forward his hand. They heard his sharp call to pitch up and the men under the point jumped. Seagrew had not yet taken his hand from his rifle. He threw it to his shoulder. As closely together as two fingers of the right hand can be struck twice in the palm of the left, two rifle shots cracked across the wash. Two bullets passed so close in flight they might have struck. One cut the dusty hair from Smith's temple and slit the brim of his hat above his ear. The other struck Seagrew under the left eye, plowed through the roof of his mouth and coming out below his ear, splintered the rock at his back. The shock alone would have staggered a bullock, but Seagrew, laughing, came forward pumping his gun. Sinclair, at 120 yards, cut instantly into the fight and the ball from his rifle creased the alkali that crusted with Spring Smith's unshaven cheek. As he fired, he sprang to cover. For Seagrew and Smith there was no cover. For one or both it was death in the open and Seagrew with his rifle at his cheek walked straight into it. Taking for a moment the fire of the three guns with Spring Smith stood a perfect target outlined against the sky. They whipped the dust from his coat toward the sleeve from his wrist and ripped the blouse collar from his neck, but he felt no bullet shock. He saw before him only the buckle of Seagrew's belt forty paces away and sent bullet after bullet at the gleam of brass between the sights. Both men were using high-pressure guns and the deadly shock of the slugs made Seagrew twitch and stagger. The man was dying as he walked. Smith's hand was racing with the lever and had a cartridge jammed the steel would have snapped like a match. It was beyond human endurance to support the leaden death. The little square of brass between the sights wavered. Seagrew stumbled, doubled on his knees and staggering plunged loosely forward on the sand. Which brings Smith through his rifle toward the boulder behind which Sinclair and Barney Redstock had disappeared. Suddenly he realized that the bullets from the point were not coming his way. He was aware of a second rifle duel above the bend. Wickwire, worming his way down the stream, had uncovered Sinclair and a young Redstock from behind. A yell between the shots rang across the wash and the cringing figure of a man ran out toward Whispering Smith with his hands high in the air and pitched headlong on the ground. It was the Sculker Barney Redstock driven out by Wickwire's fire. The shooting ceased. Silence fell upon the gloom of the dusk. Then came a calling between Smith and Wickwire and a signalling of pistol shots for their companions. Kennedy and Bob Scott dashed down toward the riverbed on their horses. Seagrew lay on his face. Young Redstock sat with his hands around his knees on the sand. Above him at some distance Wickwire and Smith stood before a man who leaned against the sharp cheek of the boulder at the point. In his hands his rifle was held across his lap just as he had dropped on his knee to fire. He had never moved after he was struck. His head, drooping a little, rested against the rock and his hat lay on the sand. His heavy beard had sunk into his chest and he kneeled in the shadow asleep. Scott and Kennedy knew him. In the mountains there was no double for Murray Sinclair. When he jumped behind the point to pick Whispering Smith off the ledge he had laid himself directly under Wickwire's fire across the wash. The first shot of the cowboy at two hundred yards had passed as he knelt through both temples. They laid him at Seagrew's side. The camp was made beside the dead men in the wash. You'd better not take him to Medicine Bend, said Whispering Smith, sitting late with Kennedy before the dying fire. It would only mean that much more unpleasant talk and notoriety for her. The inquest can be held on the Frenchman. Take him to his own ranch and telegraph the folks in Wisconsin. God knows whether they will want to hear. But his mother's there yet. But if half what Barney has told us tonight is true, it would be better if no one ever heard. End of Chapter 44 Chapter 45 of Whispering Smith by Frank Spearman. This LibriVox recording is in the public domain. Chapter 45. Back to the mountains. In the cottage on Boney Street one year later two women were waiting. It was ten o'clock at night. Isn't it a shame to be disappointed like this? complained Dixie, pushing her hair impatiently back. Really, poor George has worked to death. He was to be in at six o'clock, Mr. Lee said. And here it is ten and all your beautiful dinners spoiled. Marion, are you keeping something from me? Look me in the eye. Have you heard from Gordon Smith? No, Dixie. Not since he left the mountains a year ago? Not since he left the mountains a year ago.  It is so strange. I wonder where he is tonight. How he loves you, Marion. He told me everything when he said goodbye. He made me promise not to tell then, but I didn't promise to keep it forever. Marion smiled. A year isn't forever, Dixie. Well, it's pretty near forever when you're in love, declared Dixie energetically. I know just how he felt. She went on in a quieter tone. He felt that all the disagreeable excitement and talk we had here then bore heaviest on you. He said if he stayed in Medicine Bend, the newspapers never would cease talking and people never would stop annoying you. And, you know, George did say that we're asking to have passenger trains held here just so people could see Whispering Smith. And, Marion, think of it, he actually doesn't know yet that George and I are married. How could we notify him without knowing where he was? And he doesn't know that trains are running up the Crawling Stone Valley. Mercy, a year goes like an hour when you're in love, doesn't it? George said he knew we should hear from him within six months. And George has never yet been mistaken, accepting when he said I should grow to like the railroad business. And now it is a year and no news from him. Dixie sprang from her chair.  I think Mr. Lee handles trains shockingly every time George tries to get home like this on Saturday nights. Now don't you? And passenger trains ought to get out of the way anyway when a division superintendent is trying to get home. What difference does it make to a passenger I'd like to know whether he's a few hours less or longer in getting to California or Japan or Manila or Hong Kong or Buzzard's Gulch provided he's safe. And you know there's not been an accident on the division for a year, Marion. There's a step now. I'll bet that's George. The door opened and it was, George. Oh, honey, cried Dixie softly, waving her arms as she stood an instant before she ran to him. But haven't I been awaiting for you? Too bad. And Marion, he exclaimed, turning without releasing his wife from his arms. How can I ever make good for all this delay? Oh yes, I've had dinner. Never for heaven's sake, wait dinner for me. But wait, both of you, till you hear the news. Dixie kept her hands on his shoulders. You have heard from Whispering Smith. I have. I knew it. Wait till I get it straight. Mr. Bucks is here. I came in with him in his car. He had news of Whispering Smith. One of our freight traffic men in the Puget Sound country, who's been in a hospital in Victoria, learned by the merest accident that Gordon Smith was lying in the same hospital with typhoid fever. Marion rose swiftly. Then the time has come, thank God, when I can do something for him.  Fine, cried MacLeod. So am I. And that's why I'm late. Then I'm going to, exclaimed Dixie solemnly. Do you mean it? Ask her husband. Shall we let her, Marion? Mr. Bucks says I'm to take his car and take Barnhart and keep the car there till I can bring Gordon back. Mr. Bucks and his secretary will ride tonight as far as Bear Dance with us. And in the morning they join Mr. Glover there. MacLeod looked at his watch. If you both are going, can you be ready by twelve o'clock for the China mail? We'll be ready in an hour, declared Dixie, throwing her arm half around Marion's neck. Can't we, Marion? I can be ready in thirty minutes. Then by heaven MacLeod studded his watch. What is it, George? We won't wait for the midnight train. We will take an engine, run special to Green River, overhaul the coast limited, and save a whole day. George, pack your suitcase, quick, dear, and you too, Marion. Suitcases are all we can take, cried Dixie, pushing her husband toward the bedroom. I'll telephone Rooney Lee for an engine myself right away. Dear me, it's kind of nice to be able to order up a train when you want one in a hurry, isn't it, Marion? Perhaps I shall come to like it if they ever make George a vice president. In half an hour they had joined Bucks in his car, and Bill Dancing was piling the baggage into the vestibule. Bucks was sitting down to coffee. Chairs had been provided at the table, and after the greetings Bucks, seating Marion Sinclair at his right, and Barn Hart and MacLeod at his left, asked Dixie to sit opposite and pour the coffee.  MacLeod looked apprehensively. I'm afraid she will be assuming the whole division if you encourage her too much, Mr. Bucks. Marrying a railroad man, continued Bucks, pursuing his own thought, is as bad as marrying into the army. If you have your husband half the time, you're lucky. Then too, in the railroad business, your husband may have to be set back when the traffic falls off. It's a little light at this moment, too. How should you take it if we had to put him on a freight train for a while, Mrs. MacLeod? Oh, Mr. Bucks! Or suppose he should be promoted and should have to go to headquarters. Some of us are getting old, you know. Really? Dixie looked most demure as she filled the President's cup. Really! I often say to Mr. MacLeod that I cannot believe Mr. Bucks is president of this great road. He always looks to me to be the youngest man on the whole executive staff. Two lumps of sugar, Mr. Bucks. The bachelor president rolled his eyes as he reached for his cup. Thank you, Mrs. MacLeod, only one after that. He looked toward Marion. All I can say is that if Mrs. MacLeod's husband had married her two years earlier, he might have been general manager by this time. Nothing could hold a man back, even a man of his modesty, whose wife can say as nice things as that. By the way, Mrs. Sinclair, does this man keep you supplied with transportation? Oh, I have my annual, Mr. Bucks. Marion opened her bag to find it. Bucks held out his hand. Let me see it a moment. He adjusted his eyeglasses, looked at the pass, and called for a pen. Bucks had never lost his gracious way of doing very little things. He laid the card on the table and rode across the back of it over his name, good on all passenger trains. When he handed the card back to Marion, he turned to Dixie. Understand you are laying out two or three towns on the ranch, Mrs. MacLeod. Two or three? Oh, no! Only one as yet, Mr. Bucks. They are laying out, oh, such a pretty town, because Enlats is super-intending the street work.  You. I think Bucks makes a dandy name for a town, don't you? And I'm going to have one town named Dunning. There will be two stations on the ranch, you know, and I think really there ought to be three. As many as that. I don't believe you can operate a line that long, Mr. Bucks, with stations fourteen miles apart. Bucks opened his eyes in benevolent surprise. Dixie, on a bash, kept right on. Well, do you know how traffic is increasing over there, with the trains running only two months now? Why, the settlers are fairly pouring into the country. Will you give me a corner lot if we put another station on the ranch? I will give you two if you will give us excursions and run some of the overland passenger trains through the valley. Bucks threw back his head and laughed in his tremendous way. I don't know about that. I dare not promise offhand Mrs. McLeod, but if you can get Whispering Smith to come back, he might lay the matter before him. He used to take charge of all the colonists of business when he returns. He promised to do that before he went away for his vacation. Whispering Smith is really the man you'll have to stand in with. Whispering Smith, lying on his iron bed in the hospital, professed not to be able quite to understand why they had made such a fuss about it. He underwent the excitement of the appearance of Bernhardt in the first talk with McLeod and Dixie with hardly a rise in his temperature, and, lying in the sunshine of the afternoon, he was waiting for Marion. When she opened the door, his face was turned wistfully toward it. He held out his hands with an old smile. She ran half-blinded across the room and dropped on her knee beside him. My dear Marion, why did they drag you away out here? They did not drag me away out here. Did you expect me to sit with folded hands when I heard you were ill anywhere in the wide world? He looked hungrily at her. I didn't suppose anyone in the wide world would take it very seriously. Mr. McLeod has crushed this afternoon to think you have said you would not go back with him. You would not believe how he misses you. It's been pretty lonesome for the last year. I didn't think it could be so lonesome anywhere. Or did I? Have you noticed it? I shouldn't think you could in the mountains. Was there much water last spring? Heavens, I'd like to see the crawling stone again. Why don't you come back? He folded her hands in his own. Marion, it's you. I've been afraid I couldn't stand it to be near you and not tell you what need you be afraid to tell me. That I've loved you so long. Her head sunk close to his. Don't you know you have said it to me many times without words? I've only been waiting for a chance to tell you how happy it makes me to think it is true. End of Whispering Smith by Frank Spearman