science

Thiocarbonate

Thiocarbonate is a science 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 Thiocarbonate rather than just read about it. In short: Thiocarbonate describes a family of anions with the general chemical formula CS3−xO2−x (x = 0, 1, or 2): for x = 2 it is monothiocarbonate ion CO2S2− for x = 1 it is dithiocarbonate ion COS2−2 for x = 0 it is trithiocarbonate ion CS2−3 Like the carbonate dianion, the thiocarbonate ions are trigonal planar, with carbon atom at the center of triangle, and oxygen and sulfur atoms at the peaks of the triangle. The avera…

Key takeaways

Thiocarbonate belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Thiocarbonate to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Thiocarbonate from memory before moving on to harder problems.

Reference excerpt

Thiocarbonate describes a family of anions with the general chemical formula CS3−xO2−x (x = 0, 1, or 2):

for x = 2 it is monothiocarbonate ion CO2S2− for x = 1 it is dithiocarbonate ion COS2−2 for x = 0 it is trithiocarbonate ion CS2−3 Like the carbonate dianion, the thiocarbonate ions are trigonal planar, with carbon atom at the center of triangle, and oxygen and sulfur atoms at the peaks of the triangle. The average bond order between C and S or O is ⁠4/3⁠. The state of protonation is usually not specified. These anions are good nucleophiles and good ligands. Thiocarbonates refer to salts of those ions as well (e.g. potassium trithiocarbonate, K2CS3). Thiocarbonates refer to esters of those ions as well (e.g. dimethyl trithiocarbonate, (CH3S)2CS). They contain trigonal planar divalent functional groups R–CS3−xOx–R similar to these anions (x = 0, 1, or 2, R is organyl group). Esters with the formula R−O−C(=S)−S−R are also called xanthates, while esters with the formula R−S−C(=S)−S−R are also called thioxanthates. Thiocarbonates also refer to salts of organyl thiocarbonate ions (e.g. sodium ethyl xanthate or SEX, CH3CH2OCS−2Na+). They contain R–CS3−xO−x anions (x = 0, 1, or 2, R is organyl group). Anions with the formula R−O−CS−2, and their salts, are also called xanthates, while salts with the formula R−S−CS−2, and their salts, are also called thioxanthates.

Monothiocarbonate

Monothiocarbonate is the dianion CO2S2−, which has C2v symmetry. Monothiocarbonate arises by the hydrolysis of thiophosgene or the reaction of base with carbonyl sulfide:

COS + 2 NaOH → Na2CO2S + H2O The esters of monothiocarbonic acids are called monothiocarbonates as well (e.g. O-ethyl-S-methyl monothiocarbonate CH3CH2OC(O)SCH3).

Dithiocarbonates

Dithiocarbonate is the dianion COS2−2, which has C2v symmetry. It arises from the reaction of aqueous base with carbon disulfide:

CS2 + 2 NaOH → Na2COS2 + H2O Important derivatives of dithiocarbonates are the xanthates (O-esters of dithiocarbonates), with the formula ROCS−2. These salts are typically prepared by the reaction of sodium alkoxides with carbon disulfide. Another group of dithiocarbonates have the formula (RS)2CO. They are often derived by hydrolysis of the corresponding trithiocarbonates (RS)2CS. One example is tetrathiapentalenedione, a heterocycle that consists of two dithiocarbonate groups.

Trithiocarbonates

Trithiocarbonate is the dianion CS2−3, which has D3h symmetry. Trithiocarbonate is prepared by the reaction of sodium hydrosulfide (NaSH) with carbon disulfide:

CS2 + 2 NaSH → Na2CS3 + H2S The relatively elusive trithiocarbonic acid H2CS3 has been characterized by X-ray crystallography. Esters of thiocarbonic acid, such as dimethyl trithiocarbonate ((CH3S)2CS) are also called thioxanthate esters. Trithiocarbonate esters inhibit the enzyme carbonic anhydrase.

Perthiocarbonates Addition of sulfur to trithiocarbonate gives the perthiocarbonate anion CS2−4, which contains one sulfur–sulfur bond. Perthiocarbonic acid (or tetrathioperoxycarbonic acid / disulfanylmethanedithioic acid / CAS#13074-70-9) has never been obtained in pure form.

See also Trithiocarbonic acid Xanthate Thioxanthate Sodium ethyl xanthate (SEX) Potassium ethyl xanthate (KEX) Potassium amyl xanthate Potassium trithiocarbonate Ethyl xanthic acid

References

Illustrations

Worked examples

Example 1 — a first encounter with Thiocarbonate

Start with the simplest possible case. Write down what Thiocarbonate claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Thiocarbonate 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 Thiocarbonate 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 Thiocarbonate

In research: Thiocarbonate appears in science 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 Thiocarbonate 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: Thiocarbonate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Carbonates, Oxyanions, Sulfur ions, so understanding it makes those chapters shorter.
In everyday life: Look for Thiocarbonate 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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How to study Thiocarbonate in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Thiocarbonate means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Thiocarbonate out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Thiocarbonate in simple terms?

Thiocarbonate describes a family of anions with the general chemical formula CS3−xO2−x (x = 0, 1, or 2): for x = 2 it is monothiocarbonate ion CO2S2− for x = 1 it is dithiocarbonate ion COS2−2 for x = 0 it is trithiocarbonate ion CS2−3 Like the carbonate dianion, the thiocarbonate ions are trigonal…

Why does Thiocarbonate matter?

Because it connects several science 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 Thiocarbonate?

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 Thiocarbonate.