is nh2 more acidic than sh

The increasing s-character brings it closer to the nitrogen nucleus, reducing its tendency to bond to a proton compared to sp3 hybridized nitrogens. Jordan's line about intimate parties in The Great Gatsby? The two immiscible liquids are then easily separated using a separatory funnel. Hi, CCl3NH2 this is most basic amine. If the iodide ion is a stronger nucleophile than the hydroxide ion, why does the latter displace the former in a reaction involving aqueous Sodium hydroxide and alkyl iodide? The amine in p-methoxyaniline is shown to have more electron density, shown as a yellow color, when compared to the amine in aniline. This relationship shows that as an ammonium ion becomes more acidic (Ka increases / pKa decreases) the correspond base becomes weaker (Kb decreases / pKb increases), Weaker Base = Larger Ka and Smaller pKa of the Ammonium ion, Stronger Base = Smaller Ka and Larger pKa of the Ammonium ion. At pH 7,4 the surrounding will be more acidic than Histidine pI.It takes up a hydrogen atom at the R-group. From previous discussion it should be clear that the basicity of these nitrogens is correspondingly reduced. The equilibrium constant for this reaction is the base ionization constant (Kb), also called the base dissociation constant: \[K_b=\dfrac{[RNH3^+][OH^]}{[NH2]} \label{16.5.5}\]. Has 90% of ice around Antarctica disappeared in less than a decade? Great nucleophile, really poor base. What is the acid that reacts with this base when ammonia is dissolved in water? Table of Acid and Base Strength - University of Washington Is NH3 (Ammonia) an Acid or a Base? - Techiescientist Mention 5 of these. Please dont give wrong pka values. In other words, how much does that lone pair want to break away from the nitrogen nucleus and form a new bond with a hydrogen. NH3 pKa = 38 H2O pKa = 15.7 NH3 is a weaker acid than H2O. positive charge present on its sides , to an extent, should neutralize the intensity of the lone pair, making it somewhat stable. Most base reagents are alkoxide salts, amines or amide salts. Why does silver oxide form a coordination complex when treated with ammonia? Charged vs. noncharged species a charged molecule is more acidic than a neutral molecule pK a = 15.5 pK a = 40 CH 3OH vs CH 3NH 2 pK a = 9.4 pK . Why is ammonia so much more basic than water? Amino acids are classified using their specific R groups. Dr. Dietmar Kennepohl FCIC (Professor of Chemistry, Athabasca University), Prof. Steven Farmer (Sonoma State University), William Reusch, Professor Emeritus (Michigan State U. What is an "essential" amino acid? Please visit our recent post on this topic> Electrophilic addition. Why is ammonia more basic than acetonitrile. (o{1cd5Ugtlai"\.5^8tph0k!~D Thd6:>f&mxA4L&%ki?Cqm&/By#%i'W:XlErr'=_)i7,F|N6rm^UHW5;?h The isoelectric point (pl) for histidine (His) is 7,6. Mild oxidation of disufides with chlorine gives alkylsulfenyl chlorides, but more vigorous oxidation forms sulfonic acids (2nd example). Asking for help, clarification, or responding to other answers. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. The last two compounds (shaded blue) show the influence of adjacent sulfonyl and carbonyl groups on N-H acidity. Three examples of such reactions are shown below, with the acidic hydrogen colored red in each case. Polar acidic amino acids - contain a carboxylate (-COO-) R group . What do you call molecules with this property? In some cases triethyl amine is added to provide an additional base. NH2 - OH -F-SH - Cl-Br-I- [gasp] So it makes sense there will be at least some overlap between bases and nucleophiles. The second lone pair is not involved in the acid-base reaction, it does not point towards the -NH 4+ group. This is expected, because the -NH2 group is more electronegative than -H or -CH3. Generally, polarizability increases as you travel down a column of the periodic table (I > Br > Cl > F). Barton's base is a strong, poorly-nucleophilic, neutral base that serves in cases where electrophilic substitution of other amine bases is a problem. Strong nucleophilesthis is why molecules react. Furthermore additional nitro groups have an additive influence if they are positioned in ortho or para locations. For p-Nitroaniline virtually all of the electron density, shown as a red/yellow color. Experts are tested by Chegg as specialists in their subject area. It is noteworthy that the influence of a nitro substituent is over ten times stronger in the para-location than it is meta, despite the fact that the latter position is closer to the hydroxyl group. You will hear a lot about bulky bases, which are nucleophilic but too darn big to be a nucleophile and can only be a base. For more information on this and other topics of organic chemistry interest, please visit organic chemistry, Dr. Mike Pa got a bachelors degree in chemistry from Binghamton University, a masters degree in organic chemistry from the University of Arizona and a PhD in bio-organic chemistry from the University of Arizona. Think about it for a second.good nucleophiles (as shown above) can have a negative charge and will almost always have a lone pair. Where does this (supposedly) Gibson quote come from? { Acidity_of_Phenols : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", Acidity_of_Substituted_Phenols : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", Physical_Properties_of_Phenol : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, { Properties_of_Phenols : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", Reactivity_of_Phenols : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", Synthesis_of_Phenols : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, [ "article:topic-category", "authorname:wreusch", "showtoc:no", "license:ccbyncsa", "licenseversion:40" ], https://chem.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fchem.libretexts.org%2FBookshelves%2FOrganic_Chemistry%2FSupplemental_Modules_(Organic_Chemistry)%2FPhenols%2FProperties_of_Phenols%2FAcidity_of_Substituted_Phenols, $ \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}$ $ \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} $$\newcommand{\id}{\mathrm{id}}$ $ \newcommand{\Span}{\mathrm{span}}$ $ \newcommand{\kernel}{\mathrm{null}\,}$ $ \newcommand{\range}{\mathrm{range}\,}$ $ \newcommand{\RealPart}{\mathrm{Re}}$ $ \newcommand{\ImaginaryPart}{\mathrm{Im}}$ $ \newcommand{\Argument}{\mathrm{Arg}}$ $ \newcommand{\norm}[1]{\| #1 \|}$ $ \newcommand{\inner}[2]{\langle #1, #2 \rangle}$ $ \newcommand{\Span}{\mathrm{span}}$ $\newcommand{\id}{\mathrm{id}}$ $ \newcommand{\Span}{\mathrm{span}}$ $ \newcommand{\kernel}{\mathrm{null}\,}$ $ \newcommand{\range}{\mathrm{range}\,}$ $ \newcommand{\RealPart}{\mathrm{Re}}$ $ \newcommand{\ImaginaryPart}{\mathrm{Im}}$ $ \newcommand{\Argument}{\mathrm{Arg}}$ $ \newcommand{\norm}[1]{\| #1 \|}$ $ \newcommand{\inner}[2]{\langle #1, #2 \rangle}$ $ \newcommand{\Span}{\mathrm{span}}$$\newcommand{\AA}{\unicode[.8,0]{x212B}}$, status page at https://status.libretexts.org. Indeed, we have seen in past chapters that amines react with electrophiles in several polar reactions (see for example the nucleophilic addition of amines in the formation of imines and enamines in Section 19.8). An amino acid has this ability because at a certain pH value all the amino acid molecules exist as zwitterions. Note that this oxidation procedure is very mild and tolerates a variety of other functional groups, including those having oxidizable nitrogen and sulfur atoms. The resulting is the peptide bond. The region and polygon don't match. The only neutral acids that are stronger than ROH2+ are H2SO4 and certain other RSO3H. [0 0 792 612] >> Legal. We didnt consider the M effect of NH2 here because its not possible to donate right @MathewMahindaratne ? We really need to know what is nucleophilic and what is not so that we can determine what is going to react at the electrophilic site. Are there tables of wastage rates for different fruit and veg? Ammonia (NH 3) acts as a weak base in aqueous solution. The nitrogen of methyl amine has a significant amount of electron density on its nitrogen, shown as a red color, which accounts for it basicity compared to aniline. Solved a) the stronger acid or SH NH2 or b) the stronger | Chegg.com This is illustrated by the following examples, which are shown in order of increasing acidity. ), Virtual Textbook ofOrganicChemistry. It is nonpolar and does not exert a significant field-inductive effect, and it is incapable of delocalizing charge. Why? Bruce Edward Bursten, Catherine J. Murphy, H. Eugene Lemay, Matthew E. Stoltzfus, Patrick Woodward, Theodore E. Brown, Quiz #4 - States of Consciousness and Drugs. Finally, the two amide bases see widespread use in generating enolate bases from carbonyl compounds and other weak carbon acids. 4 0 obj Two additional points should be made concerning activating groups. In this way sulfur may expand an argon-like valence shell octet by two (e.g. 2003-2023 Chegg Inc. All rights reserved. xZMs7E&I\qrBHYZizco~z~q LDv .^-/w?ru Thus if the Ka for an ammonium ion is know the Kb for the corresponding amine can be calculated using the equation Kb = Kw / Ka. For complete conversion to the conjugate base, as shown, a reagent base roughly a million times stronger is required. Supporting evidence that the phenolate negative charge is delocalized on the ortho and para carbons of the benzene ring comes from the influence of electron-withdrawing substituents at those sites. Order of basicity for arylamines and ammonia in gas phase, Time arrow with "current position" evolving with overlay number, Follow Up: struct sockaddr storage initialization by network format-string. The electron density in the form of a lone pair is stabilized by resonance delocalization, even though there is not a negative charge involved. stream A second extraction-separation is then done to isolate the amine in the non-aqueous layer and leave behind NaCl in the aqueous layer. c) p-(Trifluoromethyl)aniline, p-methoxyaniline, p-methylaniline, 1) You can, however, force two lone pairs into close proximity. #4 Importance - within a functional group category, use substituent effects to compare acids. *;xUg!@9=XKf"aP>ax/L6ER{*UVV&r r^(>GS;E!,uf:^8:wI/s5-q'GZ8TS3qgm}lE53_;)]Uq84?1S]~3Y!upVdSO*ZeN!K4Wb>tnSd[o*ojo By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. The alcohol cyclohexanol is shown for . Alkyl groups donate electrons to the more electronegative nitrogen. How is that? RCO2 is a better nucleophile than RCO2H). The ammonium ions of most simple aliphatic amines have a pKa of about 10 or 11. stream The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. Solved SH NH2 Compound A Compound B Options: less acidic - Chegg Chemistry Stack Exchange is a question and answer site for scientists, academics, teachers, and students in the field of chemistry. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Acidic Neutral Basic Asp Asn Ser Arg Tyr Cys His Glu Gln Thr Lys Gly Ala Ile Phe Trp . Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site. I is a larger atom with a more easily broken H-I bond S is a larger atom with a more easily broken H-S bond Cl is a more electronegative atom; more polar bond Use the Periodic Trend for increasing acid strength . A similar set of resonance structures for the phenolate anion conjugate base appears below the phenol structures. After all of that, he (briefly) worked as a post-doctoral assistant at Syracuse University, working on novel organic light-emitting diodes (OLEDs). We see this in calculations and experiments that show nucleophilicity decreases as you get closer to fluorine on the periodic table (C > N > O > F). a) p-Chloroaniline, methyl p-aminobenzoate, p-nitroaniline In the first case, mild oxidation converts thiols to disufides. It is akin to saying that just because Sulphuric acid has two acidic hydrogens, it is a stronger acid than Perchloro-acid, which is untrue. This is an awesome problem of Organic Acid-Base Rea . The reasons for this different behavior are not hard to identify. $$\ce{H2N-NH2 + H3O+ <=> H3N^+-NH2 + H2O} \tag2$$. If you restrict your formulas to valence shell electron octets, most of the higher oxidation states will have formal charge separation, as in equation 2 above. Bases accept protons, with a negative charge or lone pair. inorganic chemistry - Which is more basic, hydrazine or ammonia 21.4: Acidity and Basicity of Amines is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts. LDA is a very strong base and is commonly used to create enolate ions by deprotonating an alpha-hydrogen from carbonyl compounds (Section 22-7). Of the 20 available amino acids, 9 are essential. It is common to compare basicity's of amines by using the Ka's of their conjugate acids, which is the corresponding ammonium ion. We all know that electran withdrawing ability ($-I$ effect) of $\ce{-NH2}$ group is higher than that of $\ce{-H}$ group. Thus, thermodynamics favors disulfide formation over peroxide. c. the more concentrated the acid. The addition of substituents onto the aromatic ring can can make arylamines more or less basic. However, Kb values are often not used to discuss relative basicity of amines. A limit involving the quotient of two sums, Redoing the align environment with a specific formatting. A methodical approach works best. Alternatively, a plausible general mechanism for this interesting and useful reaction is drawn below. We see some representative sulfur oxidations in the following examples. Can I tell police to wait and call a lawyer when served with a search warrant? My chemistry teacher said that $\ce{NH3}$ is more basic since after giving $\ce{H+}$ to hydrazine results in $\ce{H3N+-NH2}$, and accommodation of the lone pair of $\ce{-NH2}$ is not possible by $\ce{-N+H3}$, since it doesn't have the space. Sulfonates are sulfonate acid esters and sultones are the equivalent of lactones. Acidity of Substituted Phenols - Chemistry LibreTexts Describe the general structure of a free amino acid. Extraction is often employed in organic chemistry to purify compounds. endstream (The use of DCC as an acylation reagent was described elsewhere.) Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. (i.e. How to follow the signal when reading the schematic? This phenolic acidity is further enhanced by electron-withdrawing substituents ortho and para to the hydroxyl group, as displayed in the following diagram. Aniline is substantially less basic than methylamine, as is evident by looking at the pKa values for their respective ammonium conjugate acids (remember that the lower the pKa of the conjugate acid, the weaker the base). Comparison of amines and amides to rationalize the the pKa values of their conjugate acids. dJt#9 NH NH Compound A Compound B Options: orbital principle less acidic resonance principle induction principle more acidic atom principle Even without reference to pkas, we can predict that compound A is v than compound B by applying the. #fail During this entire time, he always loved helping students, especially if they were struggling with organic chemistry. First, the groups exert a similar effect on NH acids (and the activating sequence is the same: RSO2 > RC=O > Ph). In between, he did NOT compete at the 1996 Olympics, make the Atlanta Braves opening day roster, or become the head coach of the Indiana Pacers, as he had intended. The IUPAC name of (CH3)3CSH is 2-methyl-2-propanethiol, commonly called tert-butyl mercaptan. I am not a huge fam of memorizing charts, but this might be a good one to know pretty well. Learn more about Stack Overflow the company, and our products. Question: a) the stronger acid or SH NH2 or b) the stronger base NH2 Cl c) the greater bond angle CH3 or CH3 trans-1,2-dimethylcyclohexane d) the more stable isomer or trans-1,3-dimethylcyclohexane e) the higher boiling point CH3 f) the tertiary amine CH3 or NH2 g) the greater solubility in water h) the more stable base i) the stronger acid or This destabilizes the unprotonated form. This is because more electronegative atoms will hold electron density closer, and therefore will be less likely to let that electron density participate in a reaction. Despite their similarity, they are stronger acids and more powerful nucleophiles than alcohols. 2 0 obj Which is the stronger acid - R-OH or R-SH? - Quora g-jMGjl7{ o)?[|O&R,-W/?^,xW?1_?/g^~rWWwb/8|]ry%HD:f6%8L~vE,dqBC|.@Ms"Q2. How can I find out which sectors are used by files on NTFS? The ONLY convenient method for identifying a functional group is to already know some. Below is a table of relative nucleophilic strength. [Organic Chemistry]SH more acidic than OH : r/HomeworkHelp - reddit As noted in our earlier treatment of electrophilic aromatic substitution reactions, an oxygen substituent enhances the reactivity of the ring and favors electrophile attack at ortho and para sites. We've added a "Necessary cookies only" option to the cookie consent popup, Comparing basic strength of nitrogen heterocycles. << /Length 5 0 R /Filter /FlateDecode >> PDF Test2 ch17a Acid-Base Practice Problems - Minnesota State University 3) Polarizability The more polarizable an atom is, the more nucleophilic it will be. I am not so pleased with this argument. Organic Chemistry made easy. The most acidic functional group usually is holding the most acidic H in the entire molecule. Its basicity and nucleophilicity may be modified by steric hindrance, as in the case of 2,6-dimethylpyridine (pKa=6.7), or resonance stabilization, as in the case of 4-dimethylaminopyridine (pKa=9.7). The shifting electron density of aniline, p-nitroaniline, and p-methoxyaniline are seen in their relative electrostatic potential maps. Thus RS- will be weaker base and consequently RSH will be stronger base. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. theyve been so useful. a) the stronger acid or SH NH2 or b) the stronger base NH2 Cl c) the greater bond angle CH3 or CH3 trans-1,2-dimethylcyclohexane d) the more stable isomer or trans-1,3-dimethylcyclohexane e) the higher boiling point CH3 f) the tertiary amine CH3 or NH2 g) the greater solubility in water h) the more stable base i) the stronger acid or. This means basicity of ammonia is greater compared to that of hydrazine. The contributing structures to the phenol hybrid all suffer charge separation, resulting in very modest stabilization of this compound. After completing this section, you should be able to. describe how an amine can be extracted from a mixture that also contains neutral compounds illustrating the reactions which take place with appropriate equations. You shouldn't compare the basicity of Hydrazine as a molecule. Read "The Protonation of Acetamide and Thioacetamide in Superacidic Solutions: Crystal Structures of [H3CC(OH)NH2]+AsF6- and [H3CC(SH)NH2]+AsF6-, Zeitschrift fr anorganische und allgemeine Chemie" on DeepDyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Remember, in any case, there will be only ONE protonation at a time. An example is the formation of lithium diisopropylamide (LDA, LiN[CH(CH3)2]2) by reacting n-butyllithium with diisopropylamine (pKa 36) (Section 22-5). Due to the exothermic nature of the reaction, it is usually run at -50 C or lower. What's the difference between a power rail and a signal line? Consider the reactions for a conjugate acid-base pair, RNH3+ RNH2: \[\ce{RNH3+}(aq)+\ce{H2O}(l)\ce{RNH2}(aq)+\ce{H3O+}(aq) \hspace{20px} K_\ce{a}=\ce{\dfrac{[RNH2][H3O]}{[RNH3+]}}\], \[\ce{RNH2}(aq)+\ce{H2O}(l)\ce{RNH3+}(aq)+\ce{OH-}(aq) \hspace{20px} K_\ce{b}=\ce{\dfrac{[RNH3+][OH-]}{[RNH2]}}\]. Will that not enhance the basicity of hydrazine? This is the best answer based on feedback and ratings. Remember that, relative to hydrogen, alkyl groups are electron releasing, and that the presence of an electronreleasing group stabilizes ions carrying a positive charge. Given that the K expression for a chemical equation formed from adding two or more other equations is the mathematical product of the input equations K constants. NH NH Compound A Compound B Options: orbital principle less acidic resonance principle induction principle more acidic atom. To clarify the first part, I am not saying that the electrons will jump to the protonated nitrogen. Amines react with water to establish an equilibrium where a proton is transferred to the amine to produce an ammonium salt and the hydroxide ion, as shown in the following general equation: \[RNH2_{(aq)}+H_2O_{(l)} \rightleftharpoons RNH3^+_{(aq)}+OH^_{(aq)} \label{16.5.4}\]. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Therefore, $\ce{-NH2}$ group in $\ce{H3N^+-NH2}$ destabilizes the positive charge more than $\ce{-H}$ group in $\ce{H3N^+-H}$. The carboxyl group of one amino acid and the amino group of the incoming amino acid combine, releasing a molecule of water. How many It should be noted that the first four examples have the same order and degree of increased acidity as they exhibited decreased basicity in the previous table. << /Length 14 0 R /Filter /FlateDecode >> I looked it up and NH3 -> NH2- has a pka of 38 while H2 -> H- has a pka of 36 so they're both about the same strength, with NH2- being slightly more basic. 5 0 obj The reaction is operationally easy: a DMSO solution of the alcohol is treated with one of several electrophilic dehydrating reagents (E). Increased Basicity of para-Methoxyaniline due to Electron-Donation. The IUPAC name of (CH 3) 3 C-SH is 2-methyl-2-propanethiol, commonly called tert-butyl mercaptan. Strong nucleophiles are VERY important throughout organic chemistry, but will be especially important when trying to determine the products of elimination and substitution ( SN1 . When protonated, ammonia and hydrazine give their conjugated acids: $$\ce{NH3 + H3O+ <=> H4N+ + H2O} \tag1$$ NH2- is therefore much more basic than OH- 6 $$\ce{H2N-NH2 + H3O+ <=> H3N^+-NH2 + H2O} \tag2$$. According to the Bronsted-Lowry acid-base definition, molecules that accept protons are bases and those which are donated protons are acids. for (CH3)3C- > (CH3)2N->CH3O- And also, not to forget, hydrazine has two spots where we can get the electrons, therefore, its ambident nature should also support it's basicity. For the second point you made, more number of nucleophilic sites would mean more chances of attack of an $H^+$, which adds to the basicity of Hydrazine. While the electron density of aniline's nitrogen is delocalized in the aromatic ring making it less basic. endstream We reviewed their content and use your feedback to keep the quality high. Fortunately, the Ka and Kb values for amines are directly related. Gly is more flexible than other residues. Connect and share knowledge within a single location that is structured and easy to search. In this section we consider the relative basicity of amines. The formulas written here neutralize this charge separation by double bonding that expands the valence octet of sulfur. Sn1 proceed faster in more polar solvent compare to Sn2. Amino acids Flashcards | Quizlet Thus, the free energy difference between an alkylamine and an alkylammonium ion is less than the free energy difference between ammonia and an ammonium ion; consequently, an alkylamine is more easily protonated than ammonia, and therefore the former has a higher pKa than the latter. Thiolate conjugate bases are easily formed, and have proven to be excellent nucleophiles in SN2 reactions of alkyl halides and tosylates. Substituents which are electron-withdrawing (-Cl, -CF3, -CN, -NO2) decrease the electron density in the aromatic ring and on the amine making the arylamine less basic. View the full answer. Most of the electrophiles are good acylating reagents, so it is reasonable to expect an initial acylation of the sulfoxide oxygen. If you compare pKa values of common OH acids, you will see that ROH2+ acids (which includes H3O+ and R2OH+) are considerably stronger than neutral acids, such as RCO2H, PhOH, and ROH. NH2- Lewis Structure, Molecular Geometry, Polarity & Hybridization Which of the following will be more basic, hydrazine $\ce{H2N-NH2}$ or ammonia $\ce{NH3}$? explain why amines are more basic than amides, and better nucleophiles. An equivalent oxidation of alcohols to peroxides is not normally observed. %PDF-1.3 How much does it weigh? 6 0 R /F2.0 7 0 R >> >> Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Heres another way to think about it: the lone pair on an amide nitrogen is not as available for bonding with a proton these two electrons are too stable being part of the delocalized pi-bonding system. Although the basicity of ethers is roughly a hundred times greater than that of equivalent sulfides, the nucleophilicity of sulfur is much greater than that of oxygen, leading to a number of interesting and useful electrophilic substitutions of sulfur that are not normally observed for oxygen.

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