What is the pKa of a protonated amide?

What is the pKa of a protonated amide?

We already know that amines are basic, and that the pKa for a protonated amine is in the neighborhood of 10. We also know that, due to resonance with the carbonyl bond, amide nitrogens are not basic (in fact they are very slightly acidic, with a pKa around 20).

What is the pKa of protonated carboxylic acid?

Acidity Carboxylic acids can dissociate in aqueous solution into carboxylate ions and protons. The equilibrium constant for this process is Ka, and more frequently we talk in terms of pKa. Values of pKa for common alkyl carboxylic acids are around 5 (Ka ~ 10-5).

What is the pKa of sulfide?

7
At neutral pH, the species H2S, a weak acid (pKa 7 (2)), is in equilibrium with its conjugate base, the anion hydrosulfide (HS ).

What is the pKa of cyclohexane?

Another stabilizing effect is resonance delocalization of charge. This effect is illustrated by comparing the acidities of cyclohexane (pKa 8 52; ref 15) and cyclohexene (pKa 8 46; ref 16 ).

What is pKa of amide?

Amide. pKa = -0.4. A protonated amide possesses the least acidic group of them all (CONH+), proof that the blinking resonance form has in this case an overwhelming contribution.

What is the pKa of a protonated alcohol?

-2.4
A protonated compound is a compound that has gained an additional proton. Proto- nated alcohols and protonated carboxylic acids are very strong acids. For example, protonated methyl alcohol has a pKa of -2.5, protonated ethyl alcohol has a pKa of -2.4, and protonated acetic acid has a pKa of -6.1.

What is the pKa of ethane?

The pKa values of acetylene, ethylene, and ethane are 25, 44, and 50 respectively. This means that acetylene is the strongest acid of the three.

What has a pKa of 9?

HCl will clearly act as an acid here, and NH3 will act as a base. Our acidic product, NH4, has a pKa of 9.

How is TsOH converted to p toluenesulfonic acid?

TsOH may be converted to p -toluenesulfonic anhydride by heating with phosphorus pentoxide. When heated with acid and water, TsOH undergoes hydrolysis to toluene: CH 3 C 6 H 4 SO 3 H + H 2 O → C 6 H 5 CH 3 + H 2 SO 4 This reaction is general for aryl sulfonic acids.

Which is an example of the use of TsOH?

TsOH finds use in organic synthesis as an “organic-soluble” acid catalyst. Examples of uses include: Acetalization of an aldehyde. Esterification of carboxylic acids. Transesterification of an ester. Alkyl tosylates are alkylating agents because tosylate is electron-withdrawing as well as a good leaving group. Tosylate is a pseudohalide.

What are the values of the functional group pKa?

Approximate pKa chart of the functional groups:  values to know  1.  Protonated carbonyl  pKa = ‐7                                                   Other important pKa’s  2. Protonated alcohol or ether   pKa = ‐2 to ‐3    H2 = 35   3. Carboxylic acid   pKa = 4‐5  4. Ammonium ion   pKa = 9‐10  5. Phenol  pKa = 10  6.

What kind of water is in TsOH monohydrate?

TsOH monohydrate contains crystalline water as well as water as an impurity. To estimate the total moisture present as impurity, the Karl Fischer method is used.