chemistry

N,N,N′,N′-Tetramethylformamidinium chloride

N,N,N′,N′-Tetramethylformamidinium chloride is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand N,N,N′,N′-Tetramethylformamidinium chloride rather than just read about it. In short: N,N,N′,N′-Tetramethylformamidinium chloride is the simplest representative of quaternary formamidinium cations of the general formula [R2N−CH=NR2]+ with a chloride as a counterion in which all hydrogen atoms of the protonated formamidine [HC(=NH2)NH2]+ are replaced by methyl groups. Deprotonation results in the exceptionally basic bis(dimethylamino)carbene R2N−C̈−NR2.

Key takeaways

N,N,N′,N′-Tetramethylformamidinium chloride belongs to chemistry; place it in that map before memorising details.
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Reference excerpt

N,N,N′,N′-Tetramethylformamidinium chloride is the simplest representative of quaternary formamidinium cations of the general formula [R2N−CH=NR2]+ with a chloride as a counterion in which all hydrogen atoms of the protonated formamidine [HC(=NH2)NH2]+ are replaced by methyl groups. Deprotonation results in the exceptionally basic bis(dimethylamino)carbene R2N−C̈−NR2.

Preparation It is generated by protonation of (CH3)3COCH(N(CH3)2)2 (Bredereck's reagent).

(CH3)3COCH(N(CH3)2)2 + H+ → (CH3)3COH + [CH(N(CH3)2)2]+ N,N,N′,N′-Tetramethylformamidinium chloride is also obtained in high yield (95%) in the reaction of dimethylformamide (DMF) with dimethylcarbamoyl chlorideThe conversion of DMF with thionyl chloride in a ratio of 3:1 obtains the product in a is significantly lower yield (72%) which appears, however, more realistic in view of the tricky handling of the chloride salt.

Properties N,N,N′,N′-Tetramethylformamidinium chloride is a light yellow, strongly hygroscopic solid. For drying, the salt is dissolved in dichloromethane and the solution is treated with solid anhydrous sodium sulfate. After several dissolutions in dichloromethane and acetone, and precipitations with tetrahydrofuran, a colorless solid is obtained, which is stable under air and moisture sealing. The chloride counterion is substantially more (Lewis) basic than the amidinium is acidic; germanium dichloride or tin(II) chloride react with tetramethylformamidinium chloride to form trichloroadamantogenate(II) salts:

The hygroscopy of the chloride salt complicates the handling of the compound. Therefore, also syntheses of the much better processible salts N,N,N′,N′-tetramethylformamidinium methylsulfate (from the dimethylformamide–dimethylsulfate complex) and of N,N,N′,N′-tetramethylformamidinium p-toluenesulfonate (from dimethylformamide and p-toluenesulfonyl chloride) were investigated.

Applications N,N,N′,N′-Tetramethylformamidinium chloride is useful as a reagent for aminomethylenation (that is, to introduce a =CH−NR1R2 function to CH-acidic compounds). For example, ethyl cyanoacetate reacts with the formamidinium salt in the presence of solid sodium hydroxide to give ethyl (dimethylaminomethylene)cyanoacetate in practically quantitative yields.

The aminomethylenation provides intermediates for the synthesis of heterocycles such as indoles, pyrimidines, pyridines and quinolones. N,N,N′,N′-Tetramethylformamidinium chloride reacts with alkali metal dimethylamides (such as lithium dimethylamide or sodium dimethylamide) to tris(dimethylamino)methane in yields of 55% to 84%.

The reaction product is suited as a reagent for formylation and aminomethylenation. From N,N,N′,N′-tetramethylformamidinium chloride and sodium ethoxide in ethanol, dimethylformamide diethyl acetal is formed in 68% yield.

In aqueous sodium cyanide, N,N,N′,N′-tetramethylformamidinium reacts to bis(dimethylamino)acetonitrile.

From N,N,N′,N′-tetramethylformamidinium and anhydrous hydrogen cyanide, dimethylaminomalonic acid dinitrile is obtained in 92% yield.

N,N,N′,N′-Tetramethylformamidinium can be regaminated with cyclo-aliphatic amines to the corresponding heterocyclic formamidines.

N,N,N′,N′-tetramethylformamidinium is a catalyst in the preparation of acyl chlorides from carboxylic acids and phosgene has been reported. Strong bases (such as phenyllithium) can abstract a proton from the formamidinium cation of N,N,N′,N′-tetramethylformamidinium forming bis(dimethylamino)carbene.

Illustrations

Worked examples

Example 1 — a first encounter with N,N,N′,N′-Tetramethylformamidinium chloride

Start with the simplest possible case. Write down what N,N,N′,N′-Tetramethylformamidinium chloride claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to N,N,N′,N′-Tetramethylformamidinium chloride before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about N,N,N′,N′-Tetramethylformamidinium chloride ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of N,N,N′,N′-Tetramethylformamidinium chloride

In research: N,N,N′,N′-Tetramethylformamidinium chloride appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses N,N,N′,N′-Tetramethylformamidinium chloride in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: N,N,N′,N′-Tetramethylformamidinium chloride is common in secondary-school and first-year university syllabi. It links to neighbouring topics Amidines, Dimethylamino compounds, so understanding it makes those chapters shorter.
In everyday life: Look for N,N,N′,N′-Tetramethylformamidinium chloride outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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Frequently asked questions

What is N,N,N′,N′-Tetramethylformamidinium chloride in simple terms?

Why does N,N,N′,N′-Tetramethylformamidinium chloride matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study N,N,N′,N′-Tetramethylformamidinium chloride?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on N,N,N′,N′-Tetramethylformamidinium chloride.