Glycine, Glycine, L-Glycine, Glycocoll, H-Gly-OH, Gly, 56-40-6

GLYCINE

Glycine / Aminoacetic Acid / Glycocoll / 2-Aminoacetic acid / H-Gly-OH
CAS Number: 56-40-6
EC Number: 200-272-2

1. PRODUCT IDENTIFICATION AND CHEMICAL IDENTITY

Glycine is the smallest and simplest of the 20 standard amino acids. Its side chain consists of a single hydrogen atom, which allows it to fit into tight spaces within protein structures, such as the collagen helix. As a non-essential amino acid, glycine can be synthesized by the human body. In aqueous solution, glycine acts as a strong electrolyte (zwitterion) with both acidic and basic functional groups. It appears as a white crystalline powder, is odorless, and has a characteristic sweet taste. It has high water solubility (25 g/100 mL at 25°C), is slightly soluble in ethanol, and practically insoluble in acetone and ether. Glycine is a versatile amino acid with extensive applications in the pharmaceutical, food, feed, chemical, agricultural, and biochemical research industries.

2. PHYSICAL AND CHEMICAL PROPERTIES

3.1. Solubility Profile

Glycine is a white crystalline powder with a characteristic sweet taste. It is known for its high water solubility (25 g/100 mL at 25°C, 67.2 g/100 mL at 100°C). Its aqueous solution is slightly acidic (pH 4.0). The pKa values are 2.35 (carboxyl group) and 9.60 (amino group), explaining its zwitterionic structure. It is slightly soluble in ethanol and practically insoluble in acetone and ether. It melts and decomposes at 240°C.

3. CHEMICAL PROPERTIES AND REACTIONS

Glycine is the simplest amino acid with a side chain consisting of a single hydrogen atom. Its chemical behavior is determined by its amino and carboxyl groups.

Acid-Base Properties:

Glycine has a zwitterionic structure. pKa values: 2.35 (carboxyl) and 9.60 (amino).

Esterification:

Glycine can be esterified with alcohols to form glycine esters (e.g., glycine ethyl ester hydrochloride).

Acylation:

Glycine reacts with acid chlorides or anhydrides to form N-acyl derivatives.

Metal Chelation:

Glycine forms chelate complexes with metal ions such as magnesium, iron, copper, gold, and silver. This property is used in the food industry as an antioxidant and in electroplating.

Maillard Reaction:

Glycine participates in Maillard reactions with reducing sugars to form brown pigments and flavor compounds.

Thermal Decomposition:

Above its melting point, glycine decomposes to form ammonia, carbon dioxide, and various nitrogen-containing compounds.

Strecker Synthesis (Reverse Reaction):

Glycine can react with formaldehyde, hydrogen cyanide, and ammonia to form glycine derivatives.

4. PRODUCTION METHODS

Glycine can be produced by various industrial methods. The most common method is monochloroacetic acid amination, widely used in China.

Detailed Production Process (Monochloroacetic Acid Amination - Most Common):

1. Reaction: Ammonia water and ammonium bicarbonate are mixed and heated. Chloroacetic acid solution is added dropwise in the presence of urotropine (hexamine) catalyst.

ClCH₂COOH + 2 NH₃ → NH₂CH₂COOH + NH₄Cl

2. Crystallization: The reaction mixture is cooled, and glycine crystals are precipitated.

3. Purification: Crude glycine is recrystallized from water/methanol.

4. Drying: Purified glycine crystals are dried.

Raw Material Consumption (per ton): Chloroacetic acid (95%): 1600 kg; Liquid ammonia: 880 kg; Urotropine: 350 kg; Methanol (95%): 1100 kg.

5. PHYSIOLOGICAL FUNCTIONS AND HEALTH BENEFITS

Glycine is a non-essential amino acid that plays numerous critical physiological roles in the body. Approximately one-third of collagen is composed of glycine.

5.1. Collagen Synthesis and Tissue Health

Glycine constitutes approximately one-third of collagen and is therefore essential for skin, bone, tendon, cartilage, and joint health. It supports wound healing and tissue repair.

5.2. Neurotransmitter and Nervous System

Glycine acts as an inhibitory neurotransmitter in the central nervous system. It promotes calmness, may improve sleep quality, and may support cognitive function.

5.3. Detoxification and Antioxidant Support

Glycine helps the liver eliminate toxins and plays a role in the synthesis of glutathione, one of the body's major antioxidants. It supports metabolic balance.

5.4. Metal Chelation and Mineral Absorption

Glycine forms chelate complexes with metal ions such as magnesium, iron, copper, gold, and silver, improving the absorption and bioavailability of minerals.

6. APPLICATIONS AND INDUSTRIAL USES

6.1. Pharmaceutical Industry (Pharmaceutical Grade)

6.2. Food Industry (Food Grade)

6.3. Feed Industry (Feed Grade)

6.4. Chemical and Agricultural Industry (Technical Grade)

6.5. Biochemistry and Research

7. DOSAGE AND ADMINISTRATION

8. POTENTIAL SIDE EFFECTS AND WARNINGS

9. SAFETY AND TOXICOLOGY

10. FIRST AID MEASURES

11. SAFETY INFORMATION (GHS CLASSIFICATION)

Signal Word: WARNING

Hazard Statements (H-Codes):

Precautionary Statements (P-Codes):

12. FIREFIGHTING MEASURES

13. ACCIDENTAL RELEASE MEASURES

14. STORAGE AND HANDLING

Glycine should be stored at 2-8°C in cool, dry, well-ventilated areas, protected from moisture. It is slightly hygroscopic. It should be kept away from strong oxidizing agents. Shelf life under proper storage conditions is typically 24-36 months.

Handling Notes:

• Avoid dust generation (use enclosed systems, local exhaust ventilation)

• Avoid contact with skin and eyes (use protective gloves and goggles)

• Avoid breathing dust (use dust mask or respirator)

• Keep away from ignition sources

• Do not allow material to become wet

15. TRANSPORT INFORMATION

Glycine is not classified as a dangerous good for transport. It is shipped in 25 kg bags, drums, or FIBCs. During transport, protect from moisture, impact, and excessive heat.

16. REGULATORY INFORMATION

Regulatory Status:

17. OTHER NAMES AND DATABASE IDENTIFIERS

Database Identifiers:

18. SUMMARY AND CRITICAL WARNINGS

SUMMARY:

Glycine (C₂H₅NO₂, CAS 56-40-6) is the smallest and simplest of the 20 standard amino acids. Its side chain consists of a single hydrogen atom. It appears as a white crystalline powder, is odorless, and has a characteristic sweet taste. The molecular weight is 75.07 g/mol, density is 1.595 g/cm³, melting point is 240°C (decomposes), and water solubility at 25°C is 25 g/100 mL. It has high water solubility, is slightly soluble in ethanol, and practically insoluble in acetone and ether. As a non-essential amino acid, it plays critical roles in collagen synthesis, neurotransmission, detoxification, and antioxidant support. It has extensive applications in the pharmaceutical, food, feed, chemical, agricultural, and biochemical research industries. It is considered GRAS by the FDA. It is stored at 2-8°C in cool, dry, well-ventilated areas, protected from moisture. Packaging: 25 kg bags, drums, or FIBCs.

Key Properties:

Major Application Areas:

Key Safety Points:

• LOW TOXICITY: GRAS by FDA; LD50 (Rat) > 7,930 mg/kg

• SLIGHTLY HYGROSCOPIC: Protect from moisture; store in tightly closed containers

• MILD IRRITANT: May cause mild skin and eye irritation

• STORAGE: Store at 2-8°C in cool, dry, well-ventilated area, protected from moisture

• PPE RECOMMENDED: Dust mask, safety goggles, protective gloves (for handling powder)

• FOOD ADDITIVE: FDA GRAS; approved as food additive in many countries

CRITICAL WARNINGS:

Simplest Amino Acid: Glycine is the smallest and simplest of the 20 standard amino acids. Its side chain is a single hydrogen atom, which allows it to fit into tight spaces within protein structures, such as the collagen helix. Approximately one-third of collagen is glycine.

Zwitterionic Structure: Glycine acts as a strong electrolyte (zwitterion) in water with both acidic and basic functional groups. Its aqueous solution is slightly acidic (pH 4.0).

Food Additive Use: Glycine is GRAS by the FDA. It is permitted as a source of amino acids in food (up to 3.5% of total protein, §172.320). It is permitted as a bitter masking agent for saccharin (up to 0.2% in finished beverages, §172.812). As FEMA 3287, it is approved as a flavor enhancer in beverages, confectionery, baked goods, meat, sausages, broth, and seasonings (typical use: 150 mg/kg).

JECFA and EU Compliance: It is evaluated and accepted as a food additive by JECFA (1421). It is an approved food additive in the EU.

Flavor Enhancer: Glycine adds sweetness to foods and masks the bitter aftertaste of saccharin. It is used in soy sauce, soups, meat products, and alcoholic beverages (wine: 0.4%; champagne: 1.0%).

Antioxidant Use: Glycine extends the shelf life of cream, cheese, and margarine by metal chelation (3-4 times). It also acts as a preservative in surimi products and peanut butter by inhibiting Bacillus subtilis and E. coli (1-2%).

Neurotransmitter Effect: Glycine acts as an inhibitory neurotransmitter in the central nervous system. It promotes calmness and may improve sleep quality. High doses may cause drowsiness.

Metal Chelation: Glycine forms chelate complexes with metal ions such as magnesium, iron, copper, gold, and silver. This property is used as an antioxidant in the food industry, as a complexing agent in electroplating, and to improve mineral absorption.

Parkinson's Disease and Other Drug Syntheses: Glycine is used as a raw material for the synthesis of L-dopa (Parkinson's disease drug) and threonine.

Important Disclaimer: This Technical Data Sheet (TDS) is for informational purposes only. The information provided is based on available data and is believed to be accurate. However, the user is solely responsible for determining the suitability of the product for their specific application and for complying with all applicable regulations and safety requirements. For complete safety, handling, storage, and regulatory compliance information, always refer to the official Safety Data Sheet (SDS/MSDS) provided by the manufacturer/supplier. Users are responsible for testing the product in their own processes and applications. All local, national, and international regulations must be followed when working with glycine.