HazMat Tool — substance information

Thiourea dioxide

HMT May 2026
UN / ID
UN 3341
Hazard class
4.2
Packing group
II (multiple — see tabs)
ERG guide
ERG 135
Special provisions
SP IB6, SP IP2, SP T3, SP TP33, SP W31
Source
49 CFR §172 (2026/05)

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Thiourea dioxide


Thiourea dioxide or thiox is an organosulfur compound that is used in the textile industry. It functions as a reducing agent. It is a white solid, and exhibits tautomerism in solution. Wikipedia

Emergency Response Guide No. 135

Hazardous Materials Table

Source: 49 CFR §172 (2026/05)

(3) Hazard Class

4.2
Spontaneously combustible materials

(4) Identification number Help

UN 3341

(5) Packing Group Help

II

(6) Labels Help

Spontaneously combustible materials (4.2)

(7) Special Provisions (§172.102) Help

×Note:
Special provisions may be very complex. The extracts are taken from 49 CFR §172.102. Please be careful with the information, as necessary, additional conditions may be applied that are not written here. Please check the original source and report bugs.
IB6
IP2
T3
TP33
W31

(8) Packing Authorizations (§173.***) Help

(8A) ExceptionsNone
(8B) Non-bulk212see 49 CFR §173.212
(8C) Bulk241see 49 CFR §173.241

(9) Quantity Limits Help

(9A) Passenger aircraft/rail15 kg
(9B) Cargo aircraft only50 kg

(10) Vessel stowage Help

(10A) Location
(10B) Other n/a

(3) Hazard Class

4.2
Spontaneously combustible materials

(4) Identification number Help

UN 3341

(5) Packing Group Help

III

(6) Labels Help

Spontaneously combustible materials (4.2)

(7) Special Provisions (§172.102) Help

×Note:
Special provisions may be very complex. The extracts are taken from 49 CFR §172.102. Please be careful with the information, as necessary, additional conditions may be applied that are not written here. Please check the original source and report bugs.
IB8
IP3
T1
TP33
W31

(8) Packing Authorizations (§173.***) Help

(8A) ExceptionsNone
(8B) Non-bulk213see 49 CFR §173.213
(8C) Bulk241see 49 CFR §173.241

(9) Quantity Limits Help

(9A) Passenger aircraft/rail25 kg
(9B) Cargo aircraft only100 kg

(10) Vessel stowage Help

(10A) Location
(10B) Other n/a

Packing group comparison

Multiple packing groups apply to this entry. See assignment criteria in 49 CFR §173 Subpart D. Details are in the tabs above; differences are highlighted.

PG II PG III
1
2Thiourea dioxideThiourea dioxide
34.24.2
4UN 3341UN 3341
5IIIII
64.24.2
7IB6, IP2, T3, TP33, W31IB8, IP3, T1, TP33, W31
8ANoneNone
8B212213
8C241241
9A15 kg25 kg
9B50 kg100 kg
10ADD
10B n/a n/a

Segregation chart for load, transport, and storage

This chart shows whether loading, transport, or storage with other hazard classes is permitted, prohibited, or restricted. Based on 49 CFR §177.848.

Prohibited Must not be loaded, transported, or stored together in the same vehicle or facility.
Permitted May be loaded, transported, or stored together.
Restricted May be loaded, transported, or stored together only with restrictions.

Similar substances

UN / IDProper shipping nameHazard class
UN 1651Naphthylthiourea6.1