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chemistry

U-77891

U-77891 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 U-77891 rather than just read about it. In short: U-77891 is an opioid analgesic drug that was first synthesized in 1983 by the Upjohn company. It was originally synthesized to prove that the removal of a single methylene spacer of the benzamide would alter a κ-opioid receptor agonist such as U-50488 into an μ-opioid receptor agonist, as well as producing a semi-rigid derivative of U-47700.

U-77891 — main illustration
U-77891 — illustration

Key takeaways

  • U-77891 belongs to chemistry; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect U-77891 to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of U-77891 from memory before moving on to harder problems.

Reference excerpt

U-77891 is an opioid analgesic drug that was first synthesized in 1983 by the Upjohn company. It was originally synthesized to prove that the removal of a single methylene spacer of the benzamide would alter a κ-opioid receptor agonist such as U-50488 into an μ-opioid receptor agonist, as well as producing a semi-rigid derivative of U-47700. This would help elucidate the relative positions of the hydrogen-bond acceptors and substituted aromatic system to find the compound with the lowest Ki value in a series of benzamide opioids dating back to the 1970s. The original work found a mixture of agonists and antagonists. U-77891 acts as an agonist of the μ-opioid, δ-opioid and κ-opioid receptors with Ki values of 2, 105, and 2300 nM, respectively. The compound has ED50 values of 0.02 mg/kg and 0.21 mg/kg in mouse phenylquinone writhing and tail-flick assays. One reason for the high potency is the LogP of 4.57, allowing it to accumulate in fatty tissue such as the brain.

See also AH-7921 U-69,593

References

Illustrations

U-77891 illustration

Worked examples

Example 1 — a first encounter with U-77891

Start with the simplest possible case. Write down what U-77891 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 U-77891 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 U-77891 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 U-77891

In research
U-77891 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 U-77891 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
U-77891 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Benzamides, Bromoarenes, Mu-opioid receptor agonists, so understanding it makes those chapters shorter.
In everyday life
Look for U-77891 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 U-77891 in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what U-77891 means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain U-77891 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is U-77891 in simple terms?

U-77891 is an opioid analgesic drug that was first synthesized in 1983 by the Upjohn company. It was originally synthesized to prove that the removal of a single methylene spacer of the benzamide would alter a κ-opioid receptor agonist such as U-50488 into an μ-opioid receptor agonist, as well as p…

Why does U-77891 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 U-77891?

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 U-77891.

Tags

  • Benzamides
  • Bromoarenes
  • Mu-opioid receptor agonists
  • Spiro compounds
  • Synthetic opioids

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