What is the scope of US Patent 4,197,249 (claims 1-29)?

US Drug Patent 4,197,249 claims a family of substituted aromatic compounds defined by (i) a core formula with an aromatic system, (ii) a divalent linking moiety Q, and (iii) two N-adjacent substituents R1 and R2 with explicit structural exclusions. The claims also cover pharmacologically acceptable acid-addition salts and, in dependent form, multiple specific salt identities and specific embodiments (including free base forms and particular salt forms).

How does claim scope define the compound class (core structure + variables)?

Claim 1 and claim 2: the controlling Markush structure

Claims 1 and 2 are structurally similar, with claim 2 adding tautomers and a slightly different set of formula elements (but both use the same variable logic):

Core compound is “a compound selected from the group consisting of those of the formula” (then the formula is referenced as STR11 for claim 1 and STR13 for claim 2).
Q is a divalent moiety selected from the group of divalent moieties shown in STR12/STR14.
n is an integer from 2 to 4 inclusive.
R1 and R2 are each individually selected from:
- hydrogen
- alkyl having 1 to 4 carbons
- monohydroxyalkyl having 2 to 4 carbons
A key exclusion applies to the relationship between R1 and R2:
- “the carbon atom alpha to the nitrogen atom may not bear an hydroxy group”
- “with the proviso that R1 and R2 may not both be hydrogen or alkyl”
Both claims include:
- “and the pharmacologically acceptable acid-addition salts thereof”
- claim 2 also explicitly includes tautomers thereof

Practical reading of the variable constraints

Even without the literal drawings of STR11/STR12, the claim language constrains the family to a narrow chemical design space:

Q can vary (ethylene and other short divalent linkers indicated later in dependent claims).
R1 and R2 can vary widely (H, short alkyl, or short monohydroxyalkyl), but:
- there is an alpha-carbon hydroxy prohibition (the alpha-carbon to N cannot bear OH)
- there is a substitution participation rule: R1 and R2 cannot both be “hydrogen or alkyl” simultaneously. This is a classic way to prevent the patent from spanning the simplest non-hydroxylated dialkyl/di-H analogs.

Claim 2 adds tautomer coverage

Claim 2 includes:

“the tautomers thereof” This expands coverage to tautomeric forms that may interconvert in solution or during isolation/crystallization, without changing the underlying connectivity.

What is the structural meaning of the Q definition and its allowed range (n = 2 to 4)?

Claims 1 and 2 define Q through a set of divalent moieties (STR12/STR14) parameterized by n = 2 to 4. Dependent claims then enumerate specific Q instantiations:

Claim 17-26: Q = ethylene
Claim 22: Q = trimethylene
Claim 23: Q = —CH2 CH(CH3)— (a substituted divalent chain)
Multiple dependent claims focus on ethylene because the strongest commercially relevant embodiments are later spelled out in salt forms.

Scope effect: The independent claim scope is not “one molecule,” it is a small homolog and variant set:

n = 2 to 4 indicates a short spacer regime (consistent with ethylene, trimethylene, and analogous short divalent linkers).
The later dependent claims show the enforceable examples against competitors whose compounds share the same short spacer class plus the R1/R2 patterns.

What do R1/R2 and the hydroxy restrictions do to infringement risk?

R1 and R2 permitted substituent set

Each of R1 and R2 is selected from:

H
alkyl (1-4 C)
monohydroxyalkyl (2-4 C)

So hydroxylated side chains are allowed (for either R1 or R2), but not blindly.

Alpha-carbon hydroxy prohibition

“The carbon atom alpha to the nitrogen atom may not bear an hydroxy group” means the OH cannot be on the carbon directly adjacent to the nitrogen-bearing center (the specific atom depends on the drawn structure, but the claim unambiguously imposes a positional restriction on the hydroxy group).

Scope effect: A competitor analog with an N-adjacent secondary alcohol position does not fall within the claimed set even if it has a 2-4 carbon monohydroxyalkyl chain. The positional rule is often the difference between a design-around and an infringement.

R1/R2 “not both H or alkyl” proviso

“With the proviso that R1 and R2 may not both be hydrogen or alkyl” prevents the case where neither substituent includes the hydroxy-functional category. Put plainly:

If R1 = H (or a non-hydroxy alkyl) and R2 = H (or a non-hydroxy alkyl), the structure fails the claim.
At least one of R1 or R2 must be in the “monohydroxyalkyl” category (or otherwise not both H/alkyl in the prohibited combination).

Scope effect: The claim is built to cover molecules with required polarity/functional capability (hydroxyl-containing substitution) while avoiding the simplest dialkyl or diaryl-like analogs.

How are salt claims scoped (independent vs dependent) and what salts are explicitly covered?

General salt coverage in independent claims

Claims 1 and 2 include:

“pharmacologically acceptable acid-addition salts thereof”

This is broad and typically reads onto a large set of conventional pharmaceutically acceptable inorganic and organic acids, provided the salt is accepted for pharmaceutical use.

Dependent claims enumerate specific acids

Claims 3-16 list specific acid-addition salts covering both inorganic and organic acids:

Dependent claim	Salt acid specified
3	sulfuric acid
4	phosphoric acid
5	hydrochloric acid
6	hydrobromic acid
7	sulfamic acid
8	citric acid
9	lactic acid
10	malic acid
11	succinic acid
12	tartaric acid
13	acetic acid
14	benzoic acid
15	gluconic acid
16	ascorbic acid

Scope effect: Even if a competitor uses one of these acids (or a close variant that the examiner or courts would treat as equivalent pharmaceutically acceptable salt), the patent has a direct dependent claim to anchor enforceability.

Further dependent claims specify salt forms for specific embodiments

Claims 18-23 and 26-29 specify salt form multiplicity (di- vs disuccinate vs dihydrochloride, etc.) and form state (free base vs leuco free base vs aromatic free base).

Do the claims cover specific named embodiments, including free base and “leuco free base”?

Yes. Claims 17-29 narrow to specific combinations of Q, R1, R2, and form.

Embodiments list (as claimed)

Claim	Q	R1	R2	Form / salt form explicitly stated
17	ethylene	both R1 and R2 = β-hydroxyethyl	β-hydroxyethyl	“aromatic free base form”
18	ethylene	hydrogen	β-hydroxyethyl	“disuccinate salt form”
19	ethylene	hydrogen	β-hydroxyethyl	“dihydrochloride salt form”
20	ethylene	hydrogen	3-hydroxypropyl	“dihydrobromide salt form”
21	ethylene	hydrogen	2-hydroxypropyl	“disuccinate salt form”
22	trimethylene	hydrogen	β-hydroxyethyl	“diacetate salt form”
23	—CH2 CH(CH3)—	hydrogen	β-hydroxyethyl	“dimalate salt form”
24	ethylene	hydrogen	β-hydroxyethyl	“aromatic free base form”
25	(depends on 24)			adds “pharmacologically acceptable acid-addition salt form”
26	ethylene	hydrogen	β-hydroxyethyl	“digluconate salt form”
27	ethylene	hydrogen	β-hydroxyethyl	“dibenzoate salt form”
28	(claim 2 base)			“leuco free base form”
29	(claim 2 base)			leuco free base with R2 = 2-hydroxypropyl

Scope effect of “aromatic free base” and “leuco free base”

These terms identify specific tautomeric or oxidation-state related forms tied to the compound family:

“aromatic free base form” appears in claims 17 and 24.
“leuco free base form” appears in claims 28 and 29. Because claim 2 also includes “tautomers,” the patent is set up to cover form shifts that do not change the core connectivity.

What is the overall patent landscape logic implied by this claim set?

Enforceable coverage is built around three “pillars”

Chemical connectivity + Q class (n = 2 to 4, divalent moieties)
R1/R2 substitution logic (H/alkyl/monohydroxyalkyl plus alpha-hydroxy exclusion plus not-both-H-or-alkyl proviso)
Salt and form coverage (pharmacologically acceptable acid-addition salts plus specific acids plus explicit free base variants)

Likely infringement drivers

A competitor compound is high-risk if it matches:

Q in the short divalent set (ethylene, trimethylene, or the substituted short linker),
R1/R2 combination with at least one hydroxyl-containing substituent (and without OH on the alpha-carbon to N),
and it is marketed or formulated as one of the enumerated salts or as an accepted pharmaceutically acceptable salt.

Likely design-around levers

The claim language highlights two direct design-around levers that are both structural and specific:

Move the OH positional chemistry so the OH ends up on the disallowed alpha-carbon location or uses a non-matching monohydroxyalkyl pattern. The claim’s positional exclusion is narrow enough to matter.
Avoid the R1/R2 “not both H or alkyl” rule by using R1 and R2 pairs that are both non-hydroxy (H or alkyl) in the prohibited combination. That is a built-in carveout.

Claim-by-claim scope map (1-29)

Independent claims

Claim 1: formula family with Q (n=2-4 set), R1/R2 substitution with alpha-hydroxy exclusion and the “not both H or alkyl” proviso; covers acid-addition salts.
Claim 2: same family logic plus “tautomers” and acid-addition salts.

Dependent claims 3-16: salt acids

Broad dependent coverage enumerating 14 specific acid salts, spanning strong acids and multiple polybasic/organic acids.

Dependent claims 17-27: concrete Q/R1/R2/form exemplars

Claims 17 and 24 cover “aromatic free base form” for ethylene and β-hydroxyethyl substitution pattern(s).
Claims 18, 19, 20, 21, 22, 23, 26, 27 cover specific salt multiplicities and acid identities aligned with the enumerated salt list.

Dependent claims 28-29: leuco free base forms

Claim 28 covers “leuco free base form” for the claim 2 family.
Claim 29 locks “leuco free base form” with R2 = 2-hydroxypropyl in the ethylene-variant family logic.

Key Takeaways

US 4,197,249 claims a Markush-defined family of aromatic compounds controlled by Q (divalent moiety; n = 2 to 4) and R1/R2 (H, C1-4 alkyl, or C2-4 monohydroxyalkyl).
The scope is constrained by two structural rules: no hydroxy on the carbon alpha to N and R1 and R2 cannot both be H or alkyl.
The patent covers pharmacologically acceptable acid-addition salts broadly and also enumerates specific acids (HCl, HBr, H2SO4, H3PO4, sulfamic acid, citric, lactic, malic, succinic, tartaric, acetic, benzoic, gluconic, ascorbic).
Dependent claims enumerate concrete embodiments including ethylene vs trimethylene and specific salt multiplicities (e.g., disuccinate, dihydrochloride, digluconate, dibenzoate) plus “aromatic free base” and “leuco free base” forms.
High infringement exposure exists for competitors whose molecules match the Q range, satisfy the R1/R2 positional and substitution constraints, and are developed in claimed salt forms.

FAQs

Are acid-addition salts claimed broadly or only for specific acids?
Both. Claims 1-2 claim “pharmacologically acceptable acid-addition salts,” and claims 3-16 also explicitly list multiple specific acids.
Can a compound with any hydroxyalkyl group satisfy the claim?
No. The claim forbids an OH on the carbon alpha to the nitrogen, and it also restricts the R1/R2 combination via the “not both H or alkyl” proviso.
Does claim 2 expand coverage beyond claim 1?
Yes. Claim 2 explicitly adds tautomers of the claimed compounds.
Do the dependent claims cover free base forms as well as salts?
Yes. Claims include “aromatic free base form” and “leuco free base form,” and at least one embodiment adds that it may be converted into an acid-addition salt form.
Which Q alternatives are explicitly exemplified in dependent claims?
The dependent claims explicitly show ethylene, trimethylene, and a short substituted divalent chain (—CH2 CH(CH3)—).

References

No sources were provided beyond the claim text in the prompt.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	225884	⤷ Start Trial
Austria	359484	⤷ Start Trial
Austria	A590678	⤷ Start Trial
Australia	3877678	⤷ Start Trial
Australia	527103	⤷ Start Trial
Belgium	869688	⤷ Start Trial
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Details for Patent: 4,197,249

Summary for Patent: 4,197,249