What Are Polyamines? Structural Features, Classification and Representative Compounds, Applications, and Synthetic Strategies

1 Introduction

Polyamines are a class of nitrogen-containing organic compounds that contain multiple amine-type nitrogen atoms, or multiple amino and imino structural units within the molecule. They are widely involved in life sciences, organic synthesis, materials chemistry, environmental adsorption, and functional polymers. The core value of polyamines mainly arises from four aspects: multiple positive charges, multiple reactive sites, multiple coordination sites, and multivalent interactions. These structural features enable polyamines to interact or react with nucleic acids, proteins, metal ions, epoxy groups, carbonyl groups, isocyanates, and the surfaces of porous materials.

2 Definition of Polyamines

2.1 Chemical Definition

In the terminology of the International Union of Pure and Applied Chemistry (IUPAC), polyamine is classified under polymer structure terminology and refers to a polymer whose main chain contains imino linkage units; polymers that contain amino groups only as side-chain substituents are not included in this strict definition. However, in organic chemistry, low-molecular-weight compounds containing three or more amino groups or amine-type nitrogen sites are also commonly referred to as polyamines.

2.2 Low-Molecular-Weight Polyamines in Organic Chemistry

In organic chemistry and medicinal chemistry, polyamines are commonly used to refer to low-molecular-weight organic compounds containing three or more amine-type nitrogen atoms. For example, spermidine, spermine, and many synthetic polyamine derivatives all belong to this category. Such low-molecular-weight polyamines usually share the following common features:

① The molecule contains multiple primary, secondary, or tertiary amine structures;

② They are readily protonated in aqueous solution;

③ They exhibit strong hydrophilicity and basicity;

④ They can participate in acylation, alkylation, reductive amination, and complexation reactions;

⑤ In synthesis, selectivity control among different amine-type nitrogen atoms is often required.

2.3 Diamines Related to Natural Polyamine Systems

In life sciences, putrescine, spermidine, and spermine are often discussed together as part of the natural polyamine system. Among them, putrescine itself is 1,4-butanediamine and is structurally a diamine; cadaverine is 1,5-pentanediamine and is also a diamine.

According to the narrow organic-chemistry definition of “three or more amine-type nitrogen atoms,” putrescine and cadaverine are diamines. However, in biochemistry and natural polyamine metabolism research, they are often discussed together with spermidine, spermine, and related compounds as part of the natural polyamine system. In particular, putrescine is an important precursor in the biosynthesis of spermidine and spermine.

2.4 Scope of This Article

The polyamines discussed in this article mainly include three categories:

Type	Description	Representative Compounds
Low-molecular-weight polyamines	Small nitrogen-containing molecules with multiple amine-type nitrogen atoms	Spermidine, spermine, diethylenetriamine, triethylenetetramine
Diamines related to natural polyamine systems	Diamines closely related to natural polyamine metabolism	Putrescine, cadaverine
Polymeric polyamines	Polymers containing a large number of amine functional sites or amine structural units	Polyethylenimine, poly(amidoamine) dendrimers

3 Structural Features of Polyamines

3.1 Multiple Amine-Type Nitrogen Atoms Provide Multiple Positive Charges

Natural polyamines and many aliphatic polyamines are readily protonated in near-neutral aqueous solution, forming molecules with multiple positive charges. This polycationic character enables them to interact with negatively charged biomacromolecules and cellular components, such as deoxyribonucleic acid (DNA), ribonucleic acid (RNA), acidic or negatively charged regions in proteins, and phosphate-containing cellular components.

This polycationic character is an important basis for the involvement of natural polyamines in cellular processes. Through electrostatic interactions, hydrogen bonding, and conformational matching, polyamines can influence nucleic acid structure, protein translation, ion channel activity, and cellular metabolism.

3.2 Multiple Amine Functional Sites Provide Multiple Reactive Sites

Primary, secondary, or tertiary amine structures in polyamine molecules can participate in many organic reactions, including acylation, alkylation, reductive amination, epoxy ring opening, reactions with isocyanates, and condensation with aldehydes or ketones. Different amine structures have different reactivities:

Amine Structure Type	Structural Feature	Reaction Characteristics
Primary amine	—NH₂	Strong nucleophilicity; contains two active N—H hydrogens
Secondary amine	—NHR	Contains one active N—H hydrogen; can participate in various nucleophilic reactions
Tertiary amine	—NR₂	Contains no active N—H hydrogen; often used as a base, catalyst, or coordination site
Quaternary ammonium salt	—NR₄⁺	Carries a permanent positive charge; commonly used in cationic materials, flocculation, and antibacterial surfaces

3.3 Multiple Nitrogen Atoms Provide Coordination Ability

Nitrogen atoms can act as electron donors and form coordination interactions with metal ions. Because polyamines contain multiple nitrogen sites capable of coordination, they often exhibit strong complexation and chelation ability. This feature makes polyamines suitable for use in metal ion complexation, heavy metal adsorption, ion separation, catalytic ligand design, water-treatment materials, and surface-functionalized materials.

Poly(amidoamine) (PAMAM) dendrimers, polyethylenimine (PEI), and other materials with high nitrogen or high amine functional-site density often coordinate with metal ions through multiple amine nitrogen sites. Among them, PAMAM can also form a multipoint interaction environment through amide carbonyl oxygen atoms and neighboring functional groups. As a result, these materials are widely studied as adsorbent materials.

3.4 Nitrogen Atom Spacing and Molecular Flexibility Affect Performance

The properties of polyamines depend not only on the number of amine-type nitrogen atoms, but also on the distance between these nitrogen atoms, carbon-chain length, amine structure type, and molecular conformation. For example, spermidine and spermine are flexible linear aliphatic polyamines that can adapt to the charge distribution on the surfaces of nucleic acids and proteins. Diethylenetriamine, triethylenetetramine, and tetraethylenepentamine contain multiple ethylene or ethylene-linker segments between amine units and are therefore commonly used in complexation, curing, and crosslinking systems.

Therefore, when evaluating a polyamine molecule, the following aspects should be considered simultaneously:

① Number of amine-type nitrogen atoms;

② Ratio of primary, secondary, and tertiary amines;

③ Carbon-chain length between nitrogen atoms;

④ Whether the molecule is linear, cyclic, branched, or dendritic;

⑤ Molecular flexibility and spatial conformation;

⑥ Whether it is prone to moisture absorption, salt formation, or carbon dioxide (CO₂) uptake.

3.5 Polyamine Structures Create Selectivity Challenges

Multiple amine functional sites in polyamines may participate in reactions simultaneously. Therefore, the synthesis of polyamine derivatives often involves selectivity-control challenges. Common issues include:

① Competition among multiple amine-type nitrogen atoms;

② Insufficient selectivity between primary and secondary amines;

③ Over-alkylation;

④ Crosslinking side reactions;

⑤ High product polarity, making separation and purification difficult;

⑥ Interconversion between free-base and salt forms affecting reaction outcomes.

Polyamine synthesis often requires protecting-group strategies, such as tert-butoxycarbonyl (Boc), benzyloxycarbonyl (Cbz), 9-fluorenylmethoxycarbonyl (Fmoc), tosyl (Ts), nitrobenzenesulfonyl (Ns), and phthalimide protecting groups.

4 Classification and Representative Compounds of Polyamines

4.1 Classification by Source

Category	Representative Compounds	Main Features
Natural polyamine system	Putrescine, spermidine, spermine	Related to cell growth, nucleic acid stabilization, protein translation, and metabolic regulation
Synthetic low-molecular-weight polyamines	Diethylenetriamine, triethylenetetramine, tetraethylenepentamine	Multiple reactive sites; commonly used in synthesis, curing, complexation, and modification
Polymeric polyamines	Polyethylenimine, poly(amidoamine) dendrimers	High amine functional-site density; suitable for adsorption, delivery, and surface functionalization
Functionalized polyamines	Polyamine conjugates, polyamine-modified resins	Used in medicinal chemistry, probe design, separation materials, and functional materials

4.2 Classification by Structure

Category	Representative Compounds	Structural Features
Linear aliphatic polyamines	Spermidine, spermine, diethylenetriamine	Relatively high molecular flexibility; multiple amine-type nitrogen atoms distributed along the carbon chain
Cyclic polyamines	Piperazine and its derivatives, cyclic polyamine ligands	More fixed conformation; suitable for coordination, recognition, and medicinal structural design
Aromatic polyamines	Phenylenediamines, diaminodiphenylmethane, etc.	Stronger rigidity; commonly used in polymers, dyes, curing agents, and functional monomers
Branched polyamines	Branched polyethylenimine	High amine functional-site density; contains primary, secondary, and tertiary amines
Dendritic polyamines	Poly(amidoamine) dendrimers	Regular molecular structure; the number of terminal primary amino groups increases with generation number

4.3 Overview of Representative Polyamines

Representative Compound	English Name and Abbreviation	Structural Positioning	Main Structural Features	Typical Significance or Use
Putrescine	Putrescine	Diamine related to the natural polyamine system	1,4-Butanediamine; two terminal primary amino groups	Precursor for spermidine and spermine biosynthesis
Cadaverine	Cadaverine	Diamine related to the natural polyamine system	1,5-Pentanediamine; carbon chain longer than putrescine	Biogenic amine research; representative aliphatic diamine
Spermidine	Spermidine	Natural triamine	Contains three amine-type nitrogen atoms; flexible linear structure	Cell function regulation; related to eIF5A-specific hypusine modification
Spermine	Spermine	Natural tetraamine	Contains four amine-type nitrogen atoms; strong polycationic character	Research on nucleic acid stabilization, ion channels, and cellular regulation
Diethylenetriamine	Diethylenetriamine, DETA	Synthetic low-molecular-weight triamine	Two primary amine structures and one secondary amine structure	Intermediate, complexing agent, epoxy curing agent
Triethylenetetramine	Triethylenetetramine, TETA	Synthetic low-molecular-weight tetraamine	Linear multi-nitrogen structure	Curing, complexation, resins, and materials modification
Tetraethylenepentamine	Tetraethylenepentamine, TEPA	Synthetic low-molecular-weight pentaamine	Relatively high amine functional-site density	Adsorbent materials, curing agents, CO₂-capture material modification
Polyethylenimine	Polyethylenimine, PEI	Polymeric polyamine	Linear or branched structure; high amine functional-site density	Gene delivery, CO₂ capture, adsorption, surface modification
Poly(amidoamine) dendrimer	Polyamidoamine, PAMAM	Dendritic polyamine	Regular structure; multiple terminal primary amino groups	Delivery, adsorption, nanomaterial modification

5 Functions and Typical Applications of Polyamines

5.1 Biological Functions: Polycationic Character and Interactions with Biomacromolecules

The biological functions of natural polyamines mainly arise from their polycationic character. Putrescine, spermidine, and spermine can interact with DNA, RNA, proteins, and phosphate-containing cellular components, thereby participating in nucleic acid stabilization, protein synthesis, cell proliferation, redox balance, ion channel regulation, and cell death.

Among them, spermidine is the aminobutyl donor required for hypusination of eukaryotic translation initiation factor 5A (eIF5A). This modification is closely related to the translation of specific proteins. The involvement of polyamines in many cellular processes does not mean that a given polyamine can be directly used to treat disease.

5.2 Organic Synthesis: Polyamines Provide Nitrogen-Containing Frameworks

Polyamines are important nitrogen-containing synthetic building blocks. Their multiple amine-type nitrogen atoms allow them to be introduced into target molecules through reactions such as acylation, alkylation, reductive amination, condensation, and epoxy ring opening. Polyamines can provide both multiple nucleophilic reaction sites and flexible nitrogen-containing linker units.

Polyamines are commonly used to prepare polydentate ligands, chelating agents, pharmaceutical intermediates, polyamine conjugates, crosslinking agents, ion-exchange resins, surface modifiers, and functionalized polymers.

5.3 Epoxy Curing and Crosslinked Materials: Multiple Reactive Sites Form Networks

Polyamines can serve as important curing agents in epoxy resin systems. Primary and secondary amines can undergo ring-opening reactions with epoxy groups, forming new C—N bonds and hydroxyl groups. After multiple amine functional sites react with multiple epoxy groups, a three-dimensional crosslinked network can be formed. When polyamines are used as epoxy curing agents, the following parameters should be considered:

Parameter	Effect
Active hydrogen equivalent weight	Determines the ratio of epoxy resin to amine curing agent
Primary/secondary amine ratio	Affects curing rate, degree of reaction, and crosslink density
Molecular weight and flexible chain length	Affects toughness, hardness, and chemical resistance of the cured material
Volatility and odor	Affects the operating environment and construction safety
Amine value	Affects formulation calculation and quality control

Primary amines usually react faster than secondary amines. Tertiary amines generally do not provide active N—H hydrogens, but they can act as catalytic bases to promote epoxy curing.

5.4 Metal Ion Adsorption and Water Treatment: Multiple Nitrogen Sites Enhance Complexation Ability

Multiple primary amine, secondary amine, tertiary amine, or amide-related sites can provide a multipoint binding environment for metal ions. Nitrogen atoms in polyamines can form coordination interactions with metal ions. Therefore, polyamines and polyamine-modified materials are commonly used in heavy metal adsorption, ion separation, and water treatment.

PAMAM-modified adsorbent materials, PEI-modified porous materials, amine-functionalized silica gels, and amine-functionalized magnetic particles all make use of the affinity of nitrogen coordination sites for metal ions. Adsorption performance is usually affected by pH, ionic strength, adsorbent pore structure, amine functional-site density, contact time, and the type of target metal ion.

It should be noted that “more amine functional sites” does not necessarily mean “better adsorption.” Excessively high amine functional-site density may lead to diffusion limitations, material swelling, pore blockage, or regeneration difficulties. Therefore, a balance must be achieved between the number of binding sites and the structural stability of the material.

5.5 CO₂ Capture: Reversible Interactions Between Amine Structures and CO₂

Amine-containing materials are an important direction in CO₂-capture research. Primary and secondary amines can react with CO₂ to form carbamate-related structures. Tertiary amines do not contain N—H bonds themselves, but in the presence of water they can promote bicarbonate formation through their basicity.

Polyamines such as PEI and TEPA are often loaded onto silica, mesoporous materials, polymer supports, or other porous materials to form solid amine adsorbents. Actual CO₂-capture performance is affected by the following factors: amine structure type, amine loading, support pore structure, temperature and humidity, CO₂ partial pressure, mass-transfer resistance, and adsorption/desorption cycling stability. When polyamines are used for CO₂ capture, one should not pursue only high amine content; pore structure, diffusion efficiency, thermal stability, and regeneration performance must also be considered. For solid amine adsorbents, the spatial proximity between amine sites, the hydration state of the material, and pore-channel mass-transfer conditions also affect the formation of carbamate or bicarbonate structures and the adsorption/desorption cycling performance.

5.6 Gene Delivery and Surface Modification: Multivalent Effects of Cationic Polymers

High-density cationic amine functional sites can form electrostatic complexes with nucleic acids and influence cellular uptake and intracellular release. Cationic polymeric polyamines such as PEI can form complexes with negatively charged DNA or RNA and are therefore commonly studied for nonviral gene delivery.

However, high positive charge density may also lead to cytotoxicity, poor serum compatibility, insufficient in vivo stability, and limited targeting ability. Therefore, the use of PEI and its derivatives in biomaterials usually requires molecular-weight control, degradable linkages, hydrophilic modification, targeting-group modification, or charge shielding to improve performance.

6 Common Reagents and Strategies for Polyamine Synthesis

6.1 Direct Use of Polyamine Raw Materials

A direct approach in polyamine synthesis is to use existing polyamines as starting materials or structural units. Common starting materials include ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, DETA, TETA, TEPA, PEI, and PAMAM.

Direct use of polyamine raw materials is suitable for constructing crosslinking agents, curing agents, chelating agents, resin modifiers, and surface-functionalized materials. However, in fine synthesis, further control over the selectivity of different amine-type nitrogen atoms is often required.

6.2 C—N Bond Construction: Alkylation, Reductive Amination, and Gabriel Synthesis

6.2.1 Alkylation

Alkylation is a common method for constructing C—N bonds. Polyamines can undergo substitution reactions with alkyl halides, dihaloalkanes, mesylates, or tosylates to introduce new carbon chains or functional groups. Common reagents include:

① Alkyl chlorides, alkyl bromides, and alkyl iodides;

② Dihaloalkanes;

③ Mesylates (Ms);

④ Tosylates (Ts);

⑤ Haloalcohols;

⑥ Halonitriles;

⑦ Acrylonitrile.

A key issue in alkylation reactions is the tendency toward polyalkylation, especially when multiple primary and secondary amines are present in the same molecule. Therefore, selectivity often needs to be controlled through protecting groups, feed ratios, bases, solvents, and temperature.

6.2.2 Reductive Amination

Reductive amination is suitable for constructing substituted amines and asymmetric polyamine structures. This reaction typically involves formation of an imine or iminium ion from an aldehyde or ketone and an amine, followed by reduction to give an amine. Common reducing systems include:

① Sodium cyanoborohydride (NaBH₃CN);

② Sodium triacetoxyborohydride (NaBH(OAc)₃);

③ Catalytic hydrogenation systems, such as H₂/Pd-C;

④ Raney nickel catalytic hydrogenation systems.

Reductive amination conditions are relatively mild and are suitable for linking polyamine fragments, introducing substituents, or constructing flexible nitrogen-containing chains.

6.2.3 Gabriel Synthesis

Gabriel synthesis is commonly used to prepare primary amine structures. This method typically uses potassium phthalimide to react with alkyl halides or sulfonate esters, followed by deprotection to give primary amines. In polyamine synthesis, the Gabriel route can introduce amino groups in a protected form, reducing the risk of polyalkylation associated with direct use of amines. For complex polyamine derivatives, this method is often combined with other protecting-group strategies. It should be noted that Gabriel synthesis is generally more suitable for primary alkyl halides or activated sulfonate esters; secondary, sterically hindered, or elimination-prone substrates may give poor reaction results.

6.3 Reduction of Nitriles, Amides, Azides, and Nitro Compounds

Many nitrogen-containing functional groups can serve as latent amine sources and be converted into amines after reduction.

Precursor	Reduction Product	Common Use
Nitrile	Primary amine	Extending the carbon chain and introducing an amino group
Amide	Amine	Constructing substituted amines or polyamine frameworks
Azide	Primary amine	Mild introduction of amino groups
Nitro compound	Aromatic amine or aliphatic amine	Synthesis of aromatic polyamines
Imine/oxime	Amine	Synthesis of amine derivatives

Common reducing agents or reducing systems include lithium aluminium hydride (LiAlH₄), borane tetrahydrofuran complex (BH₃·THF), catalytic hydrogenation, and metal/acid systems. The specific method should be selected based on substrate stability, functional-group compatibility, target-product polarity, and safety requirements.

6.4 Protecting-Group Strategies: Solving Selectivity Problems in Polyamine Synthesis

The core challenge in polyamine synthesis is selectivity. Multiple amine-type nitrogen atoms may react simultaneously, so protecting groups are often required to control the reaction sequence. Common protecting groups and related reagents include:

Protecting Group or Reagent	Full Name	Main Use
Boc₂O	Di-tert-butyl dicarbonate	Introduces the Boc protecting group; usually removed under acidic conditions
Cbz-Cl	Benzyl chloroformate	Introduces the Cbz protecting group; commonly removed by hydrogenolysis
Fmoc-Cl	9-Fluorenylmethyl chloroformate	Introduces the Fmoc protecting group; commonly used for base-labile deprotection
Ts-Cl	Tosyl chloride	Introduces the Ts protecting group or activates alcohol hydroxyl groups
Ns-Cl	Nitrobenzenesulfonyl chloride	Used for amine protection and selective N-alkylation
Potassium phthalimide	Potassium phthalimide	Amino-group equivalent in Gabriel synthesis

When selecting a protecting group, four questions should be considered:

① Whether the target amine site can be selectively protected;

② Whether the protecting group can tolerate subsequent reaction conditions;

③ Whether the deprotection conditions will damage the target molecule;

④ Whether the protection and deprotection steps will significantly increase purification difficulty.

6.5 Construction Strategies for Polymeric Polyamines

Representative polymeric polyamines include PEI and PAMAM. PEI can be prepared by ring-opening polymerization of aziridine, or linear PEI can be obtained through protected monomer routes or polyoxazoline-derived routes. Branched PEI contains primary, secondary, and tertiary amines, has high amine functional-site density, and is commonly used in adsorption, delivery, and surface modification.

PAMAM is usually constructed through stepwise generation-by-generation reactions. A typical route involves alternating Michael addition and amidation or aminolysis reactions, gradually forming a dendritic structure. As the generation number increases, the number of terminal primary amino groups increases, and the molecular size and number of functional sites increase accordingly.

7 Selection and Experimental Considerations for Polyamines

7.1 Distinguishing Free Bases and Salt Forms

Polyamines often exist as free bases or hydrochloride salts. These two forms may differ significantly in solubility, basicity, stability, weighing conversion, reaction applicability, and storage conditions. Free bases usually react more directly, but they may be more hygroscopic, more prone to CO₂ uptake, or have stronger odors. Hydrochloride salts are usually more stable and easier to weigh, but when used in reactions, a base may be required to release the free amine.

7.2 Paying Attention to Amine Structure Type and Reactivity

Primary, secondary, and tertiary amines play different roles in reactions. In epoxy curing, isocyanate reactions, acylation, and alkylation, the type of amine structure directly affects reaction rate, crosslink density, and types of side reactions.

Amine Structure Type	Key Difference	Application Impact
Primary amine	Two active N—H hydrogens	High activity in epoxy curing, acylation, and crosslinking reactions
Secondary amine	One active N—H hydrogen	Can continue to participate in reactions, but usually has lower reactivity than primary amines
Tertiary amine	No active N—H hydrogen	Can serve as a base, catalyst, or coordination site
Quaternary ammonium salt	Permanent positive charge	Suitable for cationic materials and ion-exchange materials

7.3 Paying Attention to Amine Value, Active Hydrogen Equivalent Weight, and Moisture

In materials applications, amine value and active hydrogen equivalent weight are important parameters for selecting polyamines. In epoxy systems, the amount of curing agent is usually calculated based on the epoxy equivalent weight and the amine active hydrogen equivalent weight. Moisture can also affect the performance of polyamines. Excessive moisture may lead to side reactions in epoxy curing, abnormal reactions with isocyanates, changes in metal coordination performance, or reduced storage stability.

7.4 Paying Attention to Safety and Operating Conditions

Many low-molecular-weight polyamines are basic, irritating, corrosive, hygroscopic, and have noticeable odors. Some amines can irritate the skin, eyes, and respiratory tract. During laboratory or production use, personal protection requirements, ventilation conditions, storage temperature, compatibility, and spill-handling procedures should be determined according to the safety data sheet (SDS) of the specific compound.

7.5 Paying Attention to Purity and Cytotoxicity in Biological Experiments

When used in cell experiments, nucleic acid delivery, or biomaterials research, the molecular weight, dispersity, salt form, residual impurities, endotoxin level, and cytotoxicity of polyamines can all affect experimental results. Although polymers with high amine functional-site density, such as PEI, can effectively complex nucleic acids, their high positive charge density may also lead to cytotoxicity. When used in biological experiments, conditions should be optimized according to cell type, dosing concentration, molecular weight, degree of branching, and modification strategy.

8 Classification Tables of Representative Polyamine-Related Chemicals

Table 1 Natural Polyamines and Compounds Related to Natural Polyamine Systems

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Natural triamine	124-20-9	S755738	Spermidine	UltraBio™, molecular biology grade, ≥99.5% (GC)	A typical natural polyamine, used in studies of cellular function, nucleic acid interactions, and polyamine metabolism
Natural tetraamine	71-44-3	S113079	Spermine	Moligand™, for cell culture, ≥98% (GC)	A typical natural tetraamine, used in studies of nucleic acid stabilization, cellular regulation, and ion channel-related research
Natural tetraamine salt form	306-67-2	S755716	Spermine tetrahydrochloride	Moligand™, UltraBio™, molecular biology grade, ≥99.5% (AT)	A stable salt form of spermine, used in molecular biology, cell experiments, and polyamine function research
Diamine related to natural polyamine systems	110-60-1	D110948	1,4-Butanediamine	Moligand™	Putrescine structure, used in studies related to natural polyamine metabolism and the biosynthesis of spermidine and spermine
Natural triamine salt form	334-50-9	S755657	Spermidine trihydrochloride	BioReagent, ≥99.5% (AT)	A stable salt form of spermidine, used in cell culture, protein translation, and polyamine metabolism research
Diamine related to natural polyamine systems	462-94-2	D283638	1,5-Diaminopentane	≥99.5%	Cadaverine structure, used in biogenic amine analysis, aliphatic diamine research, and metabolism studies
Diamine salt form related to natural polyamine systems	333-93-7	D106194	1,4-Butanediamine dihydrochloride	≥99%	Putrescine salt form, used for polyamine standards, biogenic amine detection, and cellular metabolism research
Natural tetraamine	70862-11-2	T696265	Thermospermine	≥99%	A natural tetraamine, used in studies of plant polyamine metabolism, cell growth, and developmental regulation
Natural triamine analogue	56-18-8	D155042	3,3′-Diaminodipropylamine (dipropylenetriamine, also known as norspermidine)	≥98% (GC)	Norspermidine structure, used in studies of polycationic interactions, microbial polyamines, and synthetic polyamines
Diamine salt form related to natural polyamine systems	1476-39-7	D111805	1,5-Pentanediamine dihydrochloride	≥98%	Cadaverine salt form, used in biogenic amine analysis, metabolic detection, and standard-related experiments
Natural tetraamine analogue	4605-14-5	T281614	N,N′-Bis(3-aminopropyl)-1,3-propanediamine	≥97%	Norspermine structure, used in studies of polyamine structure–activity relationships, polycationic properties, and nucleic acid interactions

Table 2 Basic Aliphatic, Cyclic, Aromatic, and Branched Small-Molecule Polyamines

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Basic aliphatic diamine	107-15-3	E431349	Ethylenediamine (regulated explosive precursor)	Suitable for synthesis	Basic diamine raw material, used for ligands, chelating agents, crosslinking agents, and construction of polyamine frameworks
Basic aliphatic diamine	124-09-4	H103908	1,6-Hexanediamine (HMDA)	Chemical purity (CP), ≥98%	Long-chain diamine, used in epoxy curing, polymer synthesis, and crosslinked structure design
Synthetic low-molecular-weight tetraamine	112-24-3	T103762	Triethylenetetramine (TETA)	Chemical purity (CP), ≥68%	Linear polyamine raw material, used in epoxy curing, metal complexation, and resin modification
Synthetic low-molecular-weight pentaamine	112-57-2	T103795	Tetraethylenepentamine (TEPA)	Industrial grade	Raw material with high amine functional-site density, used in adsorbent materials, curing systems, and carbon dioxide capture materials
Cyclic diamine	110-85-0	P755827	Piperazine	UltraBio™, anhydrous grade, ≥99% (T)	Cyclic diamine building block, used in studies of ligands, pharmaceutical structures, polymers, and membrane materials
Synthetic low-molecular-weight triamine	111-40-0	D100056	Diethylenetriamine	Standard for GC, ≥99% (GC)	Typical triamine raw material, used for chelating agents, epoxy curing agents, and synthesis of polyamine derivatives
Basic aliphatic diamine salt form	333-18-6	E108437	Ethylenediamine hydrochloride	AR, ≥99%	Ethylenediamine salt form, used for synthetic charging, coordination systems, and stable salt-form experiments
Basic aliphatic diamine salt form	10517-44-9	P494086	1,3-Propanediamine hydrochloride	≥99.5% (4 Times Purification)	Propanediamine salt form, used for introducing polyamine chain segments and in biochemical-related experiments
Aromatic diamine	101-77-9	D108780	4,4′-Diaminodiphenylmethane (4,4′-MDA)	≥99%	Aromatic diamine, used as a polymer monomer, epoxy curing agent, and heat-resistant material component
Cyclic polyamine derivative	140-31-8	A101279	N-Aminoethylpiperazine (AEP)	≥99%	Contains primary amine, secondary amine, and cyclic amine structures; used in epoxy curing, polymer modification, and functional synthesis
Synthetic small-molecule polyamine	4067-16-7	P193281	Pentaethylenehexamine (mixture)	Reagent grade	Ethyleneamine mixture with high amine functional-site density, used in curing agents, adsorbents, and functional material preparation
Basic aliphatic diamine	109-76-2	P103898	1,3-Propanediamine	≥98%	Three-carbon-spaced diamine, used for ligands, crosslinking agents, polyamine derivatives, and surface modification
Macrocyclic tetraamine	295-37-4	T130042	1,4,8,11-Tetraazacyclotetradecane	≥98%	Macrocyclic polyamine ligand, used in studies of metal complexation, ion recognition, and functional coordination compounds
Basic aliphatic diamine salt form	6055-52-3	D134228	1,6-Hexanediamine dihydrochloride	≥98%	Hexanediamine salt form, used in long-chain diamine derivatives, polymers, and crosslinking systems
Branched small-molecule tetraamine	4963-47-7	T162014	Tris(3-aminopropyl)amine	≥97% (T)	Branched polyamine building block, used for polydentate ligands, resin modification, and surface functionalization
Macrocyclic tetraamine	294-90-6	C103173	1,4,7,10-Tetraazacyclododecane	≥97% (GC)	Macrocyclic polyamine ligand, used in metal chelating agents, coordination compounds, and precursors for labeling molecules
Synthetic low-molecular-weight tetraamine salt form	4961-40-4	T118830	Triethylenetetramine tetrahydrochloride	≥97%	Triethylenetetramine salt form, used in complexation experiments, synthetic intermediates, and salt-form control studies
Branched small-molecule tetraamine	4097-89-6	T106669	Tris(2-aminoethyl)amine (TAEA)	≥96%	Branched polyamine ligand, used in metal complexation, crosslinked structures, and dendritic molecule construction

Table 3 Polymeric Polyamines, Dendritic Polyamines, Chelating Agents, and Amine-Functionalized Materials

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Cationic polymeric polyamine	71550-12-4	P433385	Poly(allylamine hydrochloride) (PAH)	Average Mw 50,000	Cationic polymer, used in layer-by-layer assembly, surface modification, coatings, and biomaterials research
Polymeric polyamine	9002-98-6	P434400	Branched polyethylenimine (PEI)	Average Mw ~25,000 (by LS), average Mn ~10,000 (by GPC), branched	Branched polyethylenimine, used in nucleic acid complexation, carbon dioxide capture, adsorption, and surface functionalization
Amine-functionalized silane	13822-56-5	A598535	3-Aminopropyltrimethoxysilane	Chloride ion ≤13 ppm	Amine-functionalized silane, used for surface modification of silica gel, glass, oxides, and composite materials
Macrocyclic polyamine-derived chelating agent	60239-18-1	T162090	1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid	Moligand™, ≥97% (T)	Macrocyclic chelating agent, used in metal ion complexation, labeling molecules, and coordination chemistry research
Low-molecular-weight polyethylenimine	25987-06-8	P121256	Ethylenediamine-terminated polyethylenimine (PEI)	Average Mw ~800, average Mn ~600	Low-molecular-weight polyethylenimine, used in cationic polymers, adsorption, surface modification, and nucleic acid complexation research
Polyamine-derived chelating agent	60-00-4	E112487	Ethylenediaminetetraacetic acid	AR, ≥99.5%	Ethylenediamine-derived chelating agent, used in metal ion complexation, buffer systems, and analytical experiments
Polyamine-derived chelating agent	67-43-6	D108513	Diethylenetriaminepentaacetic acid (DTPA)	AR, ≥99% (T)	Diethylenetriamine-derived chelating agent, used in metal complexation, ion control, and analytical research
Dendritic polyamine	163442-67-9	P466206	PAMAM dendrimer, ethylenediamine core, generation 4.0 solution	10 wt.% in methanol	Dendritic polyamine material, used in drug delivery, metal adsorption, nanomaterial modification, and surface functionalization
Amine-functionalized silane	919-30-2	A107147	3-Aminopropyltriethoxysilane (APTS)	≥99%	Amine-functionalized silane, used in inorganic surface modification, coupling reactions, adsorbent materials, and composite material preparation
Diamine-functionalized silane	1760-24-3	T101385	N-[3-(Trimethoxysilyl)propyl]ethylenediamine	≥95%	Silane coupling agent containing a diamine structure, used for surface amine functionalization, metal adsorption, and composite material interface modification
Polyamine-functionalized silane	35141-30-1	A573515	3-[2-(2-Aminoethylamino)ethylamino]propyltrimethoxysilane	≥90%	Silane coupling agent containing a polyamine chain segment, used in adsorbent materials, carbon dioxide capture materials, and surface functionalization

Table 4 Protecting Reagents, Reducing Reagents, and Functional Building Blocks for Polyamine Synthesis

Category	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Reducing reagent for polyamine synthesis	16853-85-3	L432195	Lithium aluminium hydride (LAH)	Suitable for synthesis, powder	Strong reducing agent, used for reducing nitriles, amides, and other precursors to prepare amines and polyamine derivatives
Amine protecting reagent	28920-43-6	F432547	9-Fluorenylmethyl chloroformate	Suitable for synthesis	Introduces the fluorenylmethoxycarbonyl protecting group, used for selective protection and stepwise synthesis of polyamines
Sulfonylation and protecting reagent	98-59-9	T485782	Tosyl chloride (PTSC)	Suitable for synthesis	Used for amine protection, hydroxyl activation, and selective synthesis of polyamine derivatives
Dendritic polyamine building monomer	96-33-3	M100029	Methyl acrylate (MA)	Standard for GC, ≥99.5% (GC)	Used for generation-by-generation construction of poly(amidoamine) dendrimers and synthesis of polyamine materials
Reducing reagent for polyamine synthesis	14044-65-6	B110263	Borane tetrahydrofuran complex	1.0 M in THF, contains 5 mmol sodium borohydride stabilizer	Reducing reagent, used for converting amides, nitriles, and other nitrogen-containing precursors into amine structures
Reductive amination reagent	25895-60-7	S107168	Sodium cyanoborohydride	1.0 M in THF	Mild reductive amination reagent, used to construct substituted polyamines through reactions between aldehydes or ketones and amines
Cyanoethylation reagent	107-13-1	A299303	Acrylonitrile	≥99%, contains MEHQ stabilizer	Used for cyanoethylation of amines; subsequent reduction can introduce new amine chain segments
Amine protecting reagent	24424-99-5	D106159	Di-tert-butyl dicarbonate	≥99%	Introduces the tert-butoxycarbonyl protecting group, used in selective protection and deprotection routes for polyamines
Gabriel synthesis reagent	85-41-6	P104067	Phthalimide	≥99%	Primary amine equivalent-related reagent, used for introducing protected amino groups and in polyamine synthesis
Monoprotected diamine building block	51644-96-3	N159517	N-(tert-Butoxycarbonyl)-1,5-diaminopentane	≥98% (T)	Monoprotected cadaverine segment, used for asymmetric polyamines, polyamine conjugates, and selective synthesis
Monoprotected diamine building block	57260-73-8	B113755	N-Boc-ethylenediamine	≥98%	Monoprotected ethylenediamine building block, used for selective introduction of diamine structures and synthesis of polyamine derivatives
Monoprotected diamine building block	75178-96-0	B119879	N-tert-Butoxycarbonyl-1,3-propanediamine	≥98%	Monoprotected propanediamine building block, used for introducing flexible three-carbon amine chain segments and in polyamine synthesis
Gabriel synthesis reagent	1074-82-4	P106220	Potassium phthalimide	≥98%	Core reagent for Gabriel synthesis, used for introducing protected amino groups and preparing primary amine structures
Monoprotected diamine building block	68076-36-8	B102317	N-(tert-Butoxycarbonyl)-1,4-butanediamine	≥97%	Monoprotected putrescine segment, used for natural polyamine analogues, polyamine conjugates, and stepwise synthesis
Amine protecting reagent	501-53-1	B105737	Benzyl chloroformate	≥96%, contains 0.1% sodium carbonate as stabilizer	Introduces the benzyloxycarbonyl protecting group, used for stepwise protection of polyamines and hydrogenolysis deprotection routes
Reductive amination reagent	56553-60-7	S106573	Sodium triacetoxyborohydride (STAB)	≥90%	Mild reductive amination reagent, used to prepare substituted polyamines through reactions between aldehydes or ketones and amines

Note: The above are representative Aladdin products. For more product specifications, search by “product name/CAS/Cat. No.” on the Aladdin official website.

References

[1] IUPAC. Polyamine. IUPAC Compendium of Chemical Terminology, Gold Book.

[2] Michael A. J. Polyamines in Eukaryotes, Bacteria, and Archaea. Journal of Biological Chemistry, 2016, 291(29): 14896–14903.

[3] Pegg A. E. Functions of Polyamines in Mammals. Journal of Biological Chemistry, 2016, 291(29): 14904–14912.

[4] Kholod N. S., et al. Recent Advances in the Synthesis of Polyamine Derivatives and Their Conjugates. Molecules, 2021, 26(21): 6579.

[5] Zhang H., et al. The Adsorption of Heavy Metal Ions by Poly(amidoamine) Dendrimer Functionalized Adsorbents: A Review. Nanomaterials, 2022, 12(11): 1831.

[6] Ünveren E. E., Monkul B. Ö., Sarıoğlan Ş., Karademir N., Alper E. Solid Amine Sorbents for CO₂ Capture by Chemical Adsorption: A Review. Petroleum, 2017, 3(1): 37–50.

[7] Polyethylenimine Applications in Carbon Dioxide Capture and Separation: From Theoretical Study to Experimental Work. Energy & Fuels, 2019.

[8] Boussif O., Lezoualc’h F., Zanta M. A., Mergny M. D., Scherman D., Demeneix B., Behr J. P. A Versatile Vector for Gene and Oligonucleotide Transfer into Cells in Culture and in Vivo: Polyethylenimine. Proceedings of the National Academy of Sciences of the United States of America, 1995, 92(16): 7297–7301.

[9] May C. A. Epoxy Resins: Chemistry and Technology. 2nd ed. Marcel Dekker, 1988.

More related articles are listed below:

Isocyanate-Functional Silane Coupling Agents: Structural Features, Classification, Applications, and Selection

A Complete Guide to Selecting Epoxy Curing Systems: Amines vs. Anhydrides vs. Latent Curing — with Aladdin’s Recommended Selection Table

Understanding Amine Curing Agents: Structure, Types, and Application Selection

Silicon Reagent-Assisted Peptide Synthesis: Research Progress and Methodological Value of Peptide Bond Formation from Unprotected Substrates

Understanding Cbz (Benzyloxycarbonyl): Selection Logic and Practical Value of a Classical Amino Protecting Group

From the Logic of Deprotection to Protecting Group Choice: Differences Among Bn, PMB, and Dmb in Experimental Design

Reconsidering N-Acyl Amino Protecting Groups: Deprotection Differences, Strategic Roles, and Experimental Selection of Ac, Bz, and Tfa

Selective Deprotection and Sulfonyl Group Migration of N-Aryl Sulfonamides Mediated by TfOH (Trifluoromethanesulfonic Acid): Reaction Patterns and Synthetic Implications

Phthaloyl: Its Role in Primary Amine Protection and Practical Considerations for Experimental Selection